Twenty thousand leagues under the sea: A life cycle assessment of fibre
optic submarine cable systems
Craig Donovan
Stockholm 2009
KTH, Department of Urban Planning and Environment
Division of Environmental Strategies Research – fms
Kungliga Tekniska högskolan
Degree Project SoM EX 2009-40
www.infra.kth.se/fms
Twenty thousand leagues under the sea: A life cycle assessment of fibre optic submarine cable systems
Abstract
Submarine cables carry the vast majority of transcontinental voice and data traffic. The high capacity and
bandwidth of these cables make it possible to transfer large amounts of data around the globe almost
instantaneously. Yet, little is known about the potential environmental impacts of a submarine cable from
a life cycle perspective. This study applies Life Cycle Assessment (LCA) methodology to collect and
analyse the potential environmental impacts of a submarine cable system within a single consistent
framework. The system boundary is drawn at the limits of the terminal station where the signal is
transferred to, or from, the terrestrial network. All significant components and processes within the
system boundary have been modelled to account for the flow of resources, energy, wastes and emissions.
Data quality analysis is performed on certain variables to evaluate the effect of data uncertainties, data
gaps and methodological choices. The results highlight those activities in the life cycle of a submarine
cable that have the largest potential environmental impact; namely, electricity use at the terminal station
and cable maintenance by purpose-built ship. For example, the results show that 7 grams of carbon
dioxide equivalents (CO2 eq.) are potentially released for every ten thousand gigabit kilometres
(10,000Gb·km), given current estimations of used capacity. The potential environmental impacts are
directly linked to capacity and system usage, thus, increasing data traffic improves the environmental
performance of the submarine cable system per unit of data. A focus area for further improvements is the
emissions from ships, where the greatest gains in environmental performance are likely to be made
through reduced emissions. This study is perhaps the first tentative step in linking together research into
the environmental impact of terrestrial ICT networks.
Keywords: Life cycle assessment, LCA, submarine cables, fibre optics.
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Twenty thousand leagues under the sea: A life cycle assessment of fibre optic submarine cable systems
Executive Summary
Submarine cables carry over 97 percent of our transcontinental voice and data traffic. The world map of
submarine cable networks shows that Europe, North America and Asia are well connected with many
cable systems. Yet, little is known about the potential impacts of submarine cable systems from a life cycle
perspective. This study applies Life Cycle Assessment (LCA) methodology to collect and analyse the
potential environmental impacts of a submarine cable system within a single consistent framework. A
“cradle-to-grave” approach is considered, which begins with the extraction of raw materials from the
natural environment and ends with the return of wastes back to the environment.
The goal of this study is to undertake an LCA of a fibre optic submarine cable system in order to assess
the potential environmental impact of sending data over the cable network. To evaluate these impacts, the
modelled flows within the system must be related to a quantifiable function of the system, described as the
functional unit. The environmental impacts are described as “potential impacts” as they are not fixed in time
and space and are often related to an arbitrary functional unit. In this study the functional unit is given as
Ten thousand gigabit kilometres (10,000Gb.km), which is a scalable unit and can be interpreted as, for
example, 1.25Gb of data sent over 8,000km of submarine cable. The technological system boundary is
defined as the limits of the land terminal station where the signal is received from, or transmitted to, the
terrestrial network and includes the submarine cable, submarine repeaters and all significant components
within the terminal station. The temporal boundary is based on a commercial service lifetime of 13 years
and the geographical boundary based on a generic system in a global perspective.
Detailed data of the flows within, and crossing, the system boundary has been collected during the
inventory stage of this study. Key processes are the production of electricity and the production and
combustion of marine fuel. A total of 127 gigawatt hours (GWh) of electricity are used, given the lifetime
of 13 years, with 90 percent of this being consumed during the use & maintenance phase. Ship operations
represent the other key activity requiring a total of 179 ship days per 1000 kilometres of cable, resulting in
the combustion of a total of 1515 tonnes of fuel. A total of 54 percent of the fuel is consumed during the
use & maintenance phase, with 19 percent consumed during the installation and end-of-life recovery
phases. The end-of-life decommissioning scenario considers that the cable is recovered by purpose-built
ship and recycled for the mechanical materials, such as plastic, steel and copper. Recycling of these
particular mechanical materials is highly efficient and a “closed-loop” recycling process is modelled, which
assumes that 90 percent of the virgin material input is offset by the recycled materials.
Impact assessment is undertaken on the modelled flows based on characterisation databases. This process
assigns each flow to ten baseline impact categories based on an impact factor in relation to a single
indicator, for example, carbon dioxide equivalents (CO2 eq.) as an indicator of climate change. The ten
impact categories used in this study are; abiotic resource depletion potential, acidification potential,
ecotoxicity potential to freshwater, seawater and land, global warming potential, photochemical ozone
creation potential, ozone depletion potential, eutrophication potential, human toxicity potential.
The results show that the use & maintenance phase clearly dominates all impact categories at an average
of 66 percent. By comparison, the raw materials and design & manufacturing phases account for, on
average, only 6 percent of the total potential impact. This clearly highlights that the greatest impact over
the life cycle of a submarine cable system comes from the use & maintenance activities. Namely, electricity
use at the terminal to power the terminal equipment and the combustion of marine fuel during cable
maintenance with purpose-built ships. These are two key activities relating to the environmental
performance of the cable system. Analysis of the use & maintenance phase shows that the emissions of
CO2 equivalents are equally shared between electricity use at the terminal (47 percent) and maintenance of
the cable by purpose-built ship consuming marine fuel (53 percent). However, further analysis shows that
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Twenty thousand leagues under the sea: A life cycle assessment of fibre optic submarine cable systems
the impact, per unit of primary energy input, from the combustion of marine fuel oil has a far greater
impact on climate change than the impact from electricity use. This reflects the disparity in the
environmental impacts of electricity and fossil fuel consumption. Focusing on climate change, the results
show that a total of 7 grams of carbon dioxide equivalents (CO2 eq.) are released for every 10,000Gb.km.
This result can be applied to, for example, a telepresence conferencing system. Consider a conference
between Stockholm and New York with a distance of 8000km and a bandwidth usage of 18Mbps, then
0.1 grams of CO2 equivalents would potentially be released every second, which results in a potential
release of 355 grams of CO2 equivalents per hour. By comparison, this equates to only 3 kilometres of air
travel for a single person or 2.2 kilometres road travel by the average EU passenger car. Expanding this
example, a 2 day meeting could utilise the telepresence system for 16 hours resulting in a potential release
of 5.7kg of CO2 equivalents. By comparison, this same 2 day meeting in a face-to-face setting would
require 16,000km of air travel, resulting in a release of 1920kg of CO2. It should be noted that this
example considers only the impact of sending data via the submarine cable system and not the
telepresence system as a whole.
The function of the system is based on usage, or the actual used bandwidth, as opposed to the lit capacity,
or the present technological limitations (at the terminal) of any system. Research shows that bandwidth
usage is approximately 25 percent of current lit capacity. If this gap between usage and lit capacity was
reduced, notwithstanding technical and commercial limitations, then a subsequent gain in environmental
performance per data unit would be achieved. However, it should be noted that the overall environmental
impact over the system lifetime remains unchanged. Similarly, increased system usage, in this case
increased total data traffic, reduces the resulting potential environmental impacts per unit of data. The
sensitivity analysis (described below) supports this conclusion and shows that increasing system usage over
the 25 year technical lifetime of a submarine cable system reduces the potential environmental impact per
unit of data. From a life cycle perspective, the longer a cable remains in service, the superior the
environmental performance per unit of data. Used capacity and service life therefore have a significant
effect on determining the results.
The limitations of the study affect the final result, therefore, as recommended by the ISO 14040 series
guidelines, a sensitivity analysis has been undertaken to estimate the effect of data gaps, assumptions and
methodological choices. The submarine repeaters and terminal components are two sub-models affected
significantly by data gaps and assumptions. However, by changing parameters within these sub-models,
the sensitivity analysis shows that they have little effect on the final result. This indicates that the LCA
model is relatively unaffected by the greatest uncertainties and is thus, robust. Methodological choices
include the use of database models for the production of electricity and heavy fuel oil (HFO) and for the
combustion of HFO. The sensitivity analysis shows that methodological choices affect the final result by,
on average, approximately 20 percent. It is also important to remember, when interpreting the results, that
an LCA model is a simplification of reality.
The results of the normalisation calculation show that the relative environmental burden per capita is
relatively small. Assuming that the total annual digital media consumption (1440GB) of the average US
citizen is sent via submarine cable, then the normalised result shows that this represents only a fraction of
the total annual climate change impact, at 1.2 percent. If the aim is to reduce the environmental impact of
cable systems further, then the use & maintenance phase is the area where the greatest gains could be
made, particularly, electricity use at the terminal and the emissions from the cable ships. The greatest gain
is likely to be achieved with the reduction of ship emissions as these appear to have the most significant
impact per unit of primary energy. Service lifetime and used bandwidth are also key parameters. An
increase in either results in a corresponding decrease in the potential impact per unit of data. These are
particular areas where cable owners could direct their focus. Finally: “Without sub-sea cable systems,
global telecommunications at the level we know today would be impossible” (CPNI, 2006, p18).
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Twenty thousand leagues under the sea: A life cycle assessment off fibre optic submarine cable systems
Acknowledgements
This study has been completed to fulfil the requirements for a Master of Science at The Royal Institute of
Technology (KTH) in Stockholm, Sweden. The study was undertaken at Ericsson Research in Kista,
Stockholm and completed in the fall of 2009.
Given the broad range of data collected and analysed, many people have
have contributed to this work. Firstly,
Firstly
I would like to thank Ericsson Research, as a whole, for providing the opportunity and support to
undertake my thesis project. I would like to thank my supervisor at Ericsson Research, Fredrik Jonsson,
for his guidance and knowledge, particularly with the software program GaBi. I would like to thank my
supervisor at KTH, Åsa Moberg for her guidance on LCA methodology and for many ideas and fruitful
discussions.. I would also like to thank others at Ericsson Research, namely,
ly, Peter Håkansson, who was the
catalyst for this study and Jens Malmodin,
Malmodin who has a great depth of LCA knowledge and has given
additional support. Further, I would like to thank: Maria Löfgren
L
at Ericsson Network Technologies for
organising the site visitt to the cable manufacturing plant; Dean Veverka of Southern Cross Cables
Cable Limited
for organising the site visit to the cable terminal station in Auckland, New Zealand and for providing
many leads within the cable industry; and others working within the industry
ustry including;
including Paul Betts,
Andrew Louw and Kevin Todd.
Finally, I would like to thank my partner Sofie Dahlgren for her scientific objectivity and support during
my studies.
Stockholm, October 2009
Craig Donovan
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Twenty thousand leagues under the sea: A life cycle assessment of fibre optic submarine cable systems
Table of Contents
Abstract ........................................................................................................................................................................... ii
Executive Summary ..................................................................................................................................................... iii
Acknowledgements ....................................................................................................................................................... v
1.
2.
Introduction .......................................................................................................................................................... 1
1.1.
Background .................................................................................................................................................. 1
1.2.
Purpose and Objectives ............................................................................................................................. 1
1.3.
Problem Area and Research Questions ................................................................................................... 1
1.4.
Delimitations................................................................................................................................................ 2
1.5.
Report Structure .......................................................................................................................................... 3
Theoretical Framework ....................................................................................................................................... 4
2.1.
2.1.1.
LCA Phases ......................................................................................................................................... 4
2.1.2.
Limitations and Criticisms of LCA ................................................................................................. 6
2.2.
3.
Methodology of Life Cycle Assessment (LCA) ..................................................................................... 4
Submarine Cable Systems .......................................................................................................................... 7
2.2.1.
Historical Development .................................................................................................................... 7
2.2.2.
Modern Systems ................................................................................................................................. 8
2.2.3.
System Architecture........................................................................................................................... 9
2.2.4.
System Components ........................................................................................................................11
2.2.5.
System Design and Installation......................................................................................................13
2.2.6.
System Operation and Maintenance .............................................................................................13
2.2.7.
End-of-Life Decommissioning ......................................................................................................14
2.2.8.
Submarine verses Satellite Transmission......................................................................................15
Goal and Scope...................................................................................................................................................16
3.1.
Goal .............................................................................................................................................................16
3.1.1.
Target Audience ...............................................................................................................................16
3.1.2.
Applicability of this Study...............................................................................................................16
3.2.
Scope ...........................................................................................................................................................16
3.2.1.
System Description ..........................................................................................................................16
3.2.2.
Functional Unit ................................................................................................................................17
3.2.3.
System Boundaries and Delimitations ..........................................................................................17
3.2.4.
Data Requirements and Data Quality ...........................................................................................19
3.2.5.
Methods for Inventory Analysis ....................................................................................................20
3.2.6.
Methods for Impact Assessment...................................................................................................20
3.2.7.
Software .............................................................................................................................................21
3.2.8.
Study-Wide Assumptions, Simplifications and Limitations ......................................................22
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Twenty thousand leagues under the sea: A life cycle assessment of fibre optic submarine cable systems
3.2.9.
4.
5.
Critical Review Procedure ..............................................................................................................24
Life Cycle Inventory (LCI) ...............................................................................................................................25
4.1.
Description of System ..............................................................................................................................25
4.2.
Data Calculation ........................................................................................................................................26
4.3.
Data Collection Process ...........................................................................................................................26
4.4.
Description of Core Unit Operations and LCI Sub-Models .............................................................27
4.4.1.
Energy ................................................................................................................................................28
4.4.2.
Transportation ..................................................................................................................................29
4.4.3.
Raw Material Extraction Phase ......................................................................................................32
4.4.4.
Design & Manufacturing Phase .....................................................................................................37
4.4.5.
Installation Phase .............................................................................................................................41
4.4.6.
Use & Maintenance Phase ..............................................................................................................42
4.4.7.
End-of-Life Decommissioning Phase ..........................................................................................44
4.5.
Allocation ...................................................................................................................................................47
4.6.
Inventory Results and Discussion ..........................................................................................................48
4.6.1.
Inventory Results .............................................................................................................................48
4.6.2.
LCI Discussion .................................................................................................................................49
Life Cycle Impact Assessment (LCIA) ...........................................................................................................51
5.1.
General Allocation Procedure.................................................................................................................51
5.2.
Definition of Impact Categories and Characterisation Factors .........................................................51
5.2.1.
Abiotic Resource Depletion ...........................................................................................................52
5.2.2.
Acidification Potential .....................................................................................................................52
5.2.3.
Ecotoxicity Potential to Freshwater, Land and Seawater ..........................................................52
5.2.4.
Global Warming Potential ..............................................................................................................52
5.2.5.
Photochemical Ozone Creation Potential ...................................................................................52
5.2.6.
Ozone Depletion Potential.............................................................................................................52
5.2.7.
Eutrophication Potential.................................................................................................................53
5.2.8.
Human Toxicity Potential ..............................................................................................................53
5.3.
Classification and Characterisation Summary.......................................................................................53
5.4.
Definition of Normalisation Factors .....................................................................................................53
6.
Calculation Procedure........................................................................................................................................55
7.
Results of Life Cycle Interpretation ................................................................................................................57
7.1.
Summary of Results ..................................................................................................................................58
7.2.
Application of Results ..............................................................................................................................60
7.3.
Results by Environmental Impact Category .........................................................................................61
7.3.1.
Energy Resources.............................................................................................................................61
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Twenty thousand leagues under the sea: A life cycle assessment of fibre optic submarine cable systems
7.3.2.
Resource Depletion .........................................................................................................................63
7.3.3.
Acidification ......................................................................................................................................64
7.3.4.
Ecosystem Toxicity..........................................................................................................................65
7.3.5.
Climate Change ................................................................................................................................66
7.3.6.
Photochemical Ozone Creation ....................................................................................................67
7.3.7.
Stratospheric Ozone Depletion .....................................................................................................68
7.3.8.
Eutrophication..................................................................................................................................69
7.3.9.
Human Toxicity ...............................................................................................................................70
7.4.
Results by Life Cycle Phases ...................................................................................................................71
7.4.1.
Raw Materials....................................................................................................................................72
7.4.2.
Design & Manufacturing ................................................................................................................75
7.4.3.
Installation.........................................................................................................................................78
7.4.4.
Use & Maintenance .........................................................................................................................80
7.4.5.
End-of-Life Decommissioning ......................................................................................................84
7.5.
Data Quality Analysis ...............................................................................................................................87
7.5.1.
Sensitivity Analysis – Data gaps and uncertainties .....................................................................87
7.5.2.
Sensitivity Analysis – Methodological Choices ...........................................................................89
7.6.
Normalisation ............................................................................................................................................92
8.
Discussion ...........................................................................................................................................................93
9.
Conclusions .........................................................................................................................................................96
10.
Recommendations and Future Improvements and Use of the Model .................................................97
11.
Terminology ...................................................................................................................................................98
12.
List of Tables ..................................................................................................................................................99
13.
List of Figures ............................................................................................................................................. 100
14.
References .................................................................................................................................................... 101
14.1.
Public References ................................................................................................................................... 101
14.2.
Internal Ericsson References ............................................................................................................... 104
15.
Appendices .................................................................................................................................................. 105
15.1.
Appendix A – Calculation of the Generic Cable System ................................................................ 105
15.2.
Appendix B – Data Sources ................................................................................................................. 106
15.3.
Appendix C – Stakeholder Analysis .................................................................................................... 108
15.4.
Appendix D – Detailed System Flowchart of GaBi software sub-model .................................... 109
15.5.
Appendix E – Questionnaire to Suppliers ......................................................................................... 110
15.6.
Appendix F – Sensitivity Analysis Results ......................................................................................... 112
viii
1. Introduction
A life cycle assessment of fibre optic submarine cable systems
1. Introduction
1.1. Background
Submarine cables carry the vast majority of transcontinental voice and data traffic (NEC, 2008). The
world map of submarine cable networks (Figure 3) shows that Europe, North America and the Asia are
well connected with many cable systems spanning the oceans. The high capacity and bandwidth of these
cables makes it possible to transfer large amounts of data around the globe almost instantaneously
(Jonsson, 2009a). “Without sub-sea cable systems, global telecommunications at the level we know today
would be impossible.” (CPNI, 2006, p.18). Yet, little is known about the potential environmental impacts
of a submarine cable from a life cycle perspective (Jonsson, 2009a).
Life Cycle Assessment is a method to model the inputs and outputs of a system from “cradle-to-grave”, in
order to identify the potential environmental impacts. A “cradle-to-grave” approach begins with the
extraction of raw materials from nature and ends with the return of wastes back to nature as emissions.
(ISO 14040:2006). It is a holistic approach that collects and frames the environmental impacts into a single
consistent framework (Guinée et al, 2004). Since its early beginnings in the 1960’s, LCA has developed
into a systematic and phased methodology with guidelines defined by the International Organisation for
Standardisation (ISO 14040:2006).
This LCA study has been completed in conjunction with the EMF Safety and Sustainability division of
Ericsson Research, Stockholm, Sweden and undertaken to fulfil the requirements for the degree of Master
of Science at the Royal Institute of Technology (KTH), Stockholm, Sweden. Ericsson has been working
with life cycle assessment of their products for over 14 years. This study is seen as adding to their research
into the total environmental impact of the global network of information and communication
technologies (ICTs).
1.2. Purpose and Objectives
The purpose of this study is to make a contribution to knowledge in the field of both information and
communication technologies (ICTs) and environmental studies by undertaking a Life Cycle Assessment
(LCA) on fibre optic submarine cables systems in order to assess their potential environmental impact.
The objectives of this study are to:
•
•
•
•
Collect as complete and up-to-date data as possible for the life cycle inventory.
Construct an LCA model of the system using LCA software.
Analyse the system model to establish the potential environmental impacts.
Identify the phase or process in the life cycle of a submarine cable system that has the greatest
potential environmental impact.
1.3. Problem Area and Research Questions
The general problem field for this study is sustainable information and communication technologies (ICTs) and the
environmental impact of the global ICT network.
The specific problem area is the environmental impact of fibre optic submarine cable systems. During preliminary
research of the scientific databases and through consultation within the industry, it became apparent that
no previous LCA in the area of submarine cables had been undertaken. Therefore, it appears that a
1
1. Introduction
A life cycle assessment of fibre optic submarine cable systems
knowledge gap has been identified and the potential environmental impact of a submarine cable, given a
life cycle perspective, is unknown. Based on this knowledge gap, a number of research questions arise;
•
•
•
What are the potential environmental impacts of submarine cables given an LCA perspective?
Which activities in the life cycle of a submarine cable have the largest potential environmental
impact?
How could the potential environmental impact of those activities be reduced, or, in which activity
could the greatest reduction be achieved?
1.4. Delimitations
Research problems are often complex and inter-related (Viking and Österberg, 2004). Given the time
limitation of 20 weeks and the resource constraints of this study, some problems in the study area have
not been addressed. Following the recommended structure of an LCA report, the delimitations of this
study are discussed in relation to the system boundary presented in Section 3.2.3.
2
1. Introduction
A life cycle assessment of fibre optic submarine cable systems
1.5. Report Structure
The format for this report is based on Ericsson’s standard LCA report template which follows the
recommendations set out in the ISO guidelines (ISO 14040:2006).
The report structure is presented in Figure 1 and is summarised as follows: firstly the theory of LCA
methodology and of submarine cable systems is established; then the goal and scope of the study are
presented; next the data collection process is explained in the life cycle inventory (LCI); followed by the
life cycle impact assessment (LCIA); where after the calculation procedure and the results are presented;
followed by the discussion, conclusion and recommendations; finally the references, list of figures and
tables are detailed and the appendices are presented.
2. Theoretical
Framework
3. Goal and Scope
The details of the theoretical framework for this study are provided in this section.
Firstly the methodology of LCA is explained, secondly, the key elements of a fibre
optic submarine cable system are described.
This section describes the goal and scope of the study and details the context within
which the assessment of the environmental impacts of the system has been
determined.
4. Life Cycle
Inventory (LCI)
This section presents the system and the process of data collection and calculation.
Furthermore, a detailed description is given of the structure of the core sub-models
for the life cycle inventory of the studied system.
5. Life Cycle Impact
Assessment (LCIA)
The life cycle impact assessment (LCIA) is presented in this section, which “aims at
describing the environmental consequences of the environmental loads quantified in the
inventory analysis” (Baumann and Tillman, 2004, p.129).
6. Calculation
Procedure
7. Results of Life
Cycle Interpretation
8. Discussion
9. Conclusion
10.
Recommendations
and future use
11-14. Terminology,
List of tables and
figures, References
15. Appendices
This section describes the calculation procedure for taking the results of the LCIA and
presenting them in relation to the functional unit of the study.
In this section, the results of the life cycle interpretation are presented in relation to
the functional unit using a variety of bar charts.
A discussion of the important issues based on the results of this study is presented
here. The limitations of the study are discussed, as are the findings in relation to usage
and system capacity.
The section concludes the study and sums up the important issues and results.
Here recommendations are made based on the findings of the study. Future
improvements of the model are suggested and the use of the model is explained.
In these sections the terminology used in this report is listed, as are the tables and
figures used. Finally, the reference listing is presented for both public and internal
Ericsson reports.
This section provides additional supporting material to the main body of the report.
Figure 1: Report structure
3
2. Theoretical Framework
A life cycle assessment of fibre optic submarine cable systems
2. Theoretical Framework
This section details the theoretical framework for this study. Firstly the methodology of LCA is explained,
secondly, the key elements of a fibre optic submarine cable system are described.
2.1. Methodology of Life Cycle Assessment (LCA)
Life Cycle Assessment is a method to model the inputs and outputs of a system from “cradle-to-grave” in
order to identify the potential environmental impacts. A “cradle-to-grave” approach begins with the
extraction of raw materials from nature and ends with the return of wastes as emissions back to nature.
(ISO 14040:2006). It is a holistic approach that collects and frames the environmental impacts into a single
consistent framework (Guinée et al, 2004). An LCA attempts to map all significant resource and energy
inputs with their subsequent product (or service) and waste outputs, then, interpret the calculated
potential environmental burdens of the studied system (USEPA, 2006). LCAs can also be undertaken as a
cradle-to-gate study, where only a portion of the product or system life cycle is studied (Baumann and
Tillman, 2004). Since its early beginnings in the 1960’s, LCA has developed into a systematic and phased
methodology with guidelines defined by the International Organisation for Standardisation (ISO
14040:2006).
2.1.1. LCA Phases
The ISO guidelines identify four phases of an LCA study, as shown in Figure 2. Interpretation is
undertaken throughout the LCA and the double-ended arrows indicate the iterative nature of an LCA
study, or, the need to continually assess if the goal and scope are being fulfilled (Baumann and Tillman,
2004; EEA, 1997). The four stages of an LCA are described in the following sections.
Figure 2: LCA stages (ISO 14040:2006, p8)
4
2. Theoretical Framework
A life cycle assessment of fibre optic submarine cable systems
2.1.1.1. Goal and Scope Definition
When beginning an LCA study, clear identification of the goal and scope is important to help determine the
methodology and data requirements (Baumann and Tillman, 2004). In formulating the goal, the product,
process or activity shall be described and in what context, in other words, why the study is being carried
out (USEPA, 2006). The goal shall also state the intended application and audience, or, who will use the
results (ISO 14040:2006). The scope of the study defines the main characteristics of the LCA study in
terms of the system boundaries relating to the “temporal, geographical and technological coverage”, the
impact assessment methodology and the level of detail for the study (Guinée et al, 2004, p35). Temporal
coverage includes the definition of the period for the production, use and waste treatment for the system
(Baumann and Tillman, 2004), which in turn defines the age of data, the data collection timeframe, the
reference period for normalisation. Geographical coverage is important for assessing local or global
impact characteristics. Technological coverage may consider the least efficient case or current average
technology in the given geographical boundary (Guinée et al, 2004). Defining the system boundary is
related to the goal of the study and can be somewhat subjective, therefore, all assumptions must be clearly
stated (EEA, 1997). The limitations of the study must also be stated. These may be defined by decisions
made regarding the system boundary or through lack of data availability for certain processes. The
modelled flows within the system must be related to a quantifiable function of the system in order to
evaluate the environmental impacts. This is described as the functional unit (Baumann and Tillman,
2004). The functional unit must be defined as clearly as possible to allow for the comparison of different
systems and the evaluation of whether an equivalent function is performed (Guinée et al, 2004).
2.1.1.2. Life Cycle Inventory Analysis
The second phase in an LCA study is the life cycle inventory analysis (LCI). This is the data collection phase
where data on relevant mass and energy flows are entered into a flow model of the system (Baumann and
Tillman, 2004). It is the “process of quantifying energy and raw material requirements, atmospheric
emissions, waterborne emissions, solid wastes, and other releases for the entire life cycle of a product,
process, or activity” (USEPA, 2006, p19). The first step is to construct a detailed flowchart of the system
to identify the data requirements. The second step is data collection, which is the most time consuming
process in the LCA. Data pertaining to the raw material and energy inputs, the emissions and the product
itself, should be sought. All calculations, assumptions and data gaps should be documented. If allocation
between co-products is necessary then, data in support of the allocation method should also be collected
(Baumann and Tillman, 2004). Otherwise, the system boundaries should be expanded to include the coproducts (EEA, 1997). Validation of the data should be performed by comparison with other data or by
examining mass or energy balances (Guinée et al, 2004). The final step is calculation of the environmental
loads of the system in relation to the functional unit. This is performed by normalising the input and
output data to the defined function of the system by linking the upstream and downstream processes. The
LCI is an iterative process and the flow model may be revised as more detail is learned about the system.
(Baumann and Tillman, 2004; EEA, 1997).
2.1.1.3. Life Cycle Impact Assessment
The life cycle impact assessment (LCIA) phase takes the results of the inventory analysis and aims to translate
the environmental loads into potential environmental impacts or consequences, such as acidification or
ozone depletion. The purpose of this is to formulate the results in a format that is easier to interpret by
the intended audience (Baumann and Tillman, 2004; EEA, 1997). The LCIA is broken down into a
number of sub-phases. Impact category definition; the selection of the relevant impact categories, such as
resource depletion or global warming potential. Classification; assigning the LCI results to the relevant
impact categories. Characterisation; modelling the LCI impacts in terms of scientifically established
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A life cycle assessment of fibre optic submarine cable systems
indicators for each impact category. Grouping; the sorting and ranking of indicators, for example, by global /
regional / local impacts or by emissions to air or emissions to water. Normalisation; applying a scaling factor to the
characterisation results to relate them to a reference value, for example, background emissions in a certain
region. Weighting; assigning a relative value to the impact categories based on their perceived importance.
Data quality analysis; assessing the uncertainty and sensitivity of the data, usually involving a sensitivity
analysis on key inventory data (Baumann and Tillman, 2004; EEA, 1997; Guinée et al, 2004; USEPA,
2006). Grouping, normalisation and weighting can be considered optional elements of the LCIA (ISO
14044:2006).
2.1.1.4. Life Cycle Interpretation and Results
Interpretation is the process of assessing the results of the LCI and LCIA and presenting them in
accordance with the goal and scope of the study. As shown in Figure 2, interpretation is undertaken
throughout the LCA to continually assess if the goals and scope of the study are being fulfilled in order to
facilitate the decision making process (EEA, 1997). The elements of interpretation are; identification of the
significant environmental issues in accordance with the goal and scope of the study; evaluation of the
robustness of the model, including a discussion of choice of data, assumptions made and checks for
sensitivity and consistency of the data; making conclusions and recommendations and undertaking a critical
review of the LCA study. This final element is important to ensure the transparency of the study, that
conclusions are drawn based on facts and that the uncertainties and limitations are understood and
communicated (EEA, 1997; USEPA, 2006). A particularly good method for communicating the most
important impacts is in a bar diagram (Baumann and Tillman, 2004).
2.1.2. Limitations and Criticisms of LCA
LCA is becoming an increasingly accepted tool for evaluating environmental impacts. While software
programs and databases of generic processes are making LCA easier to perform, some limitations remain
(Hunkeler and Rebitzer, 2005). The US Environmental Protection Agency note in their LCA guidelines
that the “use of commercial software risks losing transparency in the data. Often there is no record of
assumptions or computational methods that were used. This may not be appropriate if the results are to
be used in the public domain.” (USEPA, 2006, p28).
LCA addresses only those environmental issues specified in the goal and scope. As such, LCA should not
be considered a full environmental assessment of a product system (ISO 14040:2006). Social and
economic issues are not addressed in an LCA and the environmental impacts are described as “potential
impacts” as they are not fixed in time and space and are often related to an arbitrary functional unit
(Sleeswijk et al, 2008). Furthermore, variation in the spatial and temporal dimensions of the LCI
introduces uncertainty in the results (ISO 14040:2006). Sleeswijk et al (2008) note that the results cannot
often be scaled down to the local level and that typically, an LCA focuses on the steady-state rather than a
dynamic system, in other words, not taking into account future technological advances.
The use of databases of generic processes has been criticised as these may not correspond to actual system
processes. Furthermore, that unpublished proprietary data is unverifiable therefore, it is often impossible
to determine the reliability of data. The disregard for elementary mass balance is a further criticism. The
mass of the inputs should equal the mass of the outputs (Ayres, 1995).
Methodologies for assessing the consistency and accuracy of inventory data are generally lacking, which
can lead to uncertainty and inconsistency in the results (ISO 14040:2006). It is argued that within the
LCIA phase there has been a lack of consistency regarding which impact categories to include. Efforts are
underway to provide guidelines on recommended LCIA practice however, given the current lack of
agreement, this is no small undertaking (Bare and Gloria, 2006; ISO 14040:2006).
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A life cycle assessment of fibre optic submarine cable systems
Lack of validation in LCA is another criticism. Validation is the process of assessing the LCA model to see
if it, in fact, mimics and behaves equally to the real system (Ciroth and Becker, 2006). If LCA studies can
be validated, then Ciroth and Becker (2006) conclude it would provide improved models and thus, an
improvement in the quality of decision making based on those models.
Finally, LCA should be considered an analytical tool used to support decision making. It should not be
relied upon to replace the decision making process rather, be used in conjunction with other evidence to
assist in decision making (Sleeswijk et al, 2008).
2.2. Submarine Cable Systems
Communication by submarine cable has a long history, dating back over 150 years to the first telegraph
cable between England and France. The first transoceanic cable was completed shortly after connecting
England with the US. Since these early origins technology has developed from analogue telegraph and
coaxial transmission, to high speed/high capacity digital transmission over fibre optic networks. A map of
the global fibre optic submarine cable systems is shown in Figure 3.
Figure 3: World map of submarine cables (Alcatel, 2009)
2.2.1. Historical Development
Communication by submarine cable has been described as having followed an “evolutionary process…
punctuated by a series of epochal events marking technological advances” and, regulatory change
(Beaufils, 2000, p15). This era began when the very first telegraph cable was laid in 1850 across the
English Channel, from Dover to Calais. The first attempt at a transoceanic cable was undertaken in 1857
(Letellier, 2004), though it was not until 1866 that the first successful transoceanic cable was installed
between the UK and the US. The second age of submarine communication was the development of the
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A life cycle assessment of fibre optic submarine cable systems
first coaxial cables for submarine use in the 1950s. The first transoceanic cable to carry voice
communication was Trans-Atlantic Telephone 1 (TAT-1), laid in 1956. This cable had a capacity of 36
circuits however, 15 of those circuits were only ever sold.
Figure 4: Development of submarine cables (Hilt, 2009)
The development of digital technology using optical fibre in the 1980s was the catalyst to facilitate rapid
expansion of modern telecommunications. Fibre optic technology dramatically increased cable capacity
relative to construction and maintenance costs, thereby increasing the returns (Beaufils, 2000). The first
fibre optic submarine cable was laid in the Canary Islands 1985 and the second between the UK and
Belgium in 1986 (Amano and Iwamoto, 1990). The first transoceanic fibre optic cable was Trans-Atlantic
Telephone 8 (TAT-8), installed in 1988. At the time, this cable provided more capacity than all previous
cables combined with 280Mbps or 35,000 voice circuits over 2 fibre pairs (Letellier, 2004). A timeline of
submarine cable development is shown in Figure 4.
2.2.2. Modern Systems
Modern fibre optic systems are composed of a number of key components; the submarine cable,
submarine repeaters, branching units, submarine line terminal equipment (SLTE), and the power feed
equipment (PFE) (Letellier, 2004).
As the light signal travels along the fibre it becomes degraded and consequently, longer systems need to be
amplified at regular intervals by submarine repeaters. The repeaters are powered by approximately one
ampere (1A) of direct current supplied from the terminal station via a copper conductor built into the
cable. The early fibre optic cable systems used electronic amplifiers within the repeater, where the signal
was regenerated and retransmitted by a light source within the repeater. As technology progressed, purely
optical repeaters, which work by “exciting” the existing light signal, were developed. This created an endto-end optical channel. The first fully optical system was installed in 1995 (ibid). This was a major
development, as optically amplified systems can generally be upgraded without replacement of the cable or
subsea components. This is achieved by upgrading the transmission and network management systems at
the terminal station to provide faster transmission and more signals per fibre. Wave division multiplexing
(WDM) is used to transmit more than one active signal or light wavelength on a fibre-pair1. By upgrading
the WDM equipment, more optical channels can be added to a fibre-pair without upgrading the
submarine cable (Beaufils, 2000). Greater flexibility, security and resilience is also provided with optical
1
Fibres are designed to function in pairs to support transmission in both directions (Letellier, 2004).
8
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A life cycle assessment of fibre optic submarine cable systems
add/drop multiplexing (OADM) and optical cross-connect (OXC) networking, where signals can be
converted or exchanged between wavelengths (Akiba and Yamamoto, 1998). Current technology provides
10Gbps transmission rates, with hundreds of wavelengths possible on a single fibre-pair (André and
Brochier, 2007). However, there are technical limitations to the maximum transmission rates and number
of wavelengths depending on age of the system (Beaufils, 2000). Research and development continues.
Recently, it was demonstrated that 40Gbps transmission on a single wavelength was possible over the
Atlantic using the existing TAT-14 cable, built in 2001 (Städje, 2009) and single-channel bit rates have
attainted 100Gbps in other experiments (Gnauck and Chraplyvy, 2008).
2.2.3. System Architecture
Systems are designed in a variety of configurations depending on the requirements of the network. There
are three principle configurations; unrepeated, branched or ringed systems, described in more detail in the
following sections.
2.2.3.1. Unrepeated systems
Unrepeated systems are typically 200-300 kilometres long and use point-to-point architecture. They do not
have built in submarine repeaters and therefore, do not need to be powered along the length of the cable.
However, due to the limiting factors of signal loss and corruption, unrepeated systems are unlikely to
exceed 500 kilometres in length. The cable is design so that amplification takes place at both the
transmitting and receiving terminal stations. Unrepeated systems have been used extensively in
interconnecting the British Isles and in connecting the UK to Europe. Festoon systems are a series of
unrepeated point-to-point cables connected into a network (Alcatel, 2009; CPNI, 2006). Figure 5 shows a
typical unrepeated festoon system.
ADM: Add/Drop Multiplexer
TM: Terminal Multiplexer
Figure 5: Unrepeated "festoon" system (adapted from Alcatel, 2009)
2.2.3.2. Branched systems
Branched systems are designed for long routes that service several countries from a single trunk cable.
Due to their length, electrically powered repeaters must be installed along the length of the cable to
counteract the signal losses in the fibre (CPNI, 2006). Branching units, also acting as repeaters in some
cases, are placed at the junction between the landfall cable and the trunk cable to direct the signals along
the appropriate paths. These systems are used extensively between Europe and the Far East. They are
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A life cycle assessment of fibre optic submarine cable systems
particularly beneficial where neighbouring countries are hostile toward one another as cables are generally
routed in international waters (Alcatel 2009; CPNI, 2006). Figure 6 shows a typical branched system.
TM: Terminal Multiplexer
Figure 6: Branched system architecture (adapted from Alcatel, 2009)
2.2.3.3. Ringed systems
Ringed systems were designed to provide redundancy in the event of a cable fault in a point-to-point
system. As technology developed, new cables were installed that had more capacity than all former cables
combined and hence, there was a need to provide redundant capacity and back-up in the event of a cable
fault. This was achieved by constructing the cable as a ringed network with two separate oceanic legs. Due
to their length, ringed systems require repeaters and a powered cable, similar to branched systems. This
type of system architecture is utilised particularly across the Atlantic and Pacific Oceans to connect the US
with, Europe, Asia and Australasia. (Alcatel 2009; CPNI, 2006; Ruddy, 2006). Figure 7 shows a typical
ringed system.
ADM: Add/Drop Multiplexer
Figure 7: Ring system architecture (adapted from Alcatel, 2009)
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A life cycle assessment of fibre optic submarine cable systems
2.2.4. System Components
The main components of a submarine cable system are the submarine cable itself, the repeaters and
branching units and the terminal station equipment, as shown in Figure 8.
Figure 8: Components of a submarine cable system (Letellier, 2004)
2.2.4.1. Submarine Cable
Submarine cable is designed to protect the optical fibres2 from a hostile marine environment. The cable
must be able to withstand the tensions induced during installation and recovery, variable seabed
conditions (such as rock or steep slopes) and the high pressures of deep sea installation down to 8,000m
(Beaufils, 2000). Cables are built around the fibre unit structure; a metal tube designed to house the fibres in a
stress-free environment and contains the fibres and a water blocking gel used (Fullenbaum, 2004). For
deepwater3 installation, the fibre unit structure is typically surrounded with strengthening wire, the copper
conductor and then, high-density polyethylene for insulation and abrasion resistance (see lightweight
cable, Figure 9). Various levels of armouring using carbon steel wires and bitumen sealant are built around
this basic cable structure to protect the cable in shallow water, where the majority of faults occur (Letellier,
2004). Cables are designed to withstand the marine environment for 25 years (Beaufils, 2000).
2
Optical fibre strands are very clear, flexible filaments of glass, slightly thicker than a human hair (Corning, 2009).
The division between shallow water and deepwater is normally considered to be the 1000 metre contour (Trischitta
et al, 1997).
3
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2. Theoretical Framework
A life cycle assessment of fibre optic submarine cable systems
Figure 9: Types of submarine cable: Double Armoured (DA), Single Armoured (SA), Lightweight Protected
(LWP) and Lightweight (LW) (Beaufils, 2000).
2.2.4.2. Repeaters and Branching Units
Repeaters and branching units are contained in pressure resistant structural housings made from specially
blended alloys, such as, beryllium copper of nickel-chrome-molybdenum (Amano and Iwamoto, 1990).
Similar to the cable, they must be able to withstand the tensions induced during installation and recovery
and the high pressures of deep sea installation down to 8,000m. As a transoceanic system may require
hundreds of repeaters to be installed along the route, they have stringent standards for reliability (Letellier,
2004). Recovery and replacement of a submerged plant involves considerable time, cost and disruption to
service. The repeater manufacturer Fujitsu, for example, has never had a ship-based repair and has
delivered roughly 2400 repeaters (Harasawa et al, 2008). The distance between repeaters is typically 40 to
110 kilometres and is dependent on the total system length (Suyama et al, 1999; Letellier, 2004).
Section 2.2.2 provides additional details on repeaters.
2.2.4.3. Terminal Equipment
The link between the submerged plant and the terrestrial networks is the cable terminal station. The main
components of the terminal are the submarine line terminal equipment (SLTE) and the power feed
equipment (PFE) (Trischitta et al, 1997), with additional support equipment such as, batteries and back-up
generators to supply continuous power in the event of failure in the main supply.
The SLTE controls the transmission and receive of the light wave signals through the following
components: High Precision Optical Equipment (HPOE) for transmitting and receiving each signal;
Initial Loading Equipment (ILE) to load the unused spectrum of the channel wavelengths; Line
Monitoring Equipment (LME) to detect errors in the subsea plant; Wavelength Terminating Equipment
(WTE) to combine or separate the individual light wave signals; Terminal Line Amplifier (TLA) to
strengthen the signal before being sent or received (Breverman et al, 2007). All of these components are
housed within standard floor standing racks within the terminal station (Oikawa et al, 2006). The
components of the SLTE are shown in Figure 10.
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2. Theoretical Framework
A life cycle assessment of fibre optic submarine cable systems
HPOE: High Precision Optical Equipment
ILE:
Initial Loading Equipment
LME:
Line Monitoring Equipment
WTE:
Wavelength Terminating Equipment
TLA:
Terminal Line Amplifier
STM:
Synchronous Transport Mode
Figure 10: Architecture of the SLTE (Breverman et al, 2007)
The PFE supplies a direct current of approximately one ampere (1A) to the repeaters via the copper
conductor in the cable. Two systems are used in parallel, each capable of supporting the entire load in the
event of failure in one system. Depending on the configuration, a PFE can generate up to 10 kilovolts
(10kV) in order to power the hundreds of repeaters in a transoceanic system (Letellier, 2004). The PFE
consists of direct current converters and monitoring equipment housed within standardised floor
mounted racks within the terminal station (Alcatel, 1998).
2.2.5. System Design and Installation
Once the decision has been taken to construct a new system, the planning and implementation phase
begins. This phase is critical for the long-term reliability of the network. The cable must be designed and
installed to be protected from external aggression, such as, commercial fishing, anchoring and hostile
seabed. All of this information is collected during the feasibility study known as the desktop study (Beaufils,
2000). This identifies the best route and estimates cable types and burial requirements. Following the
desktop study, the electronic route survey (ERS) and the electronic burial assessment survey (EBAS)
begin. The two surveys are completed by a research ship that collects the geophysical profile of the seabed
along the route (Letellier, 2004) to map the topography, identify hazards and evaluate sediments (Beaufils,
2000). This data then facilitates the final system design and allows for the assembly of the sections of the
submerged plant. For protection against external aggression, the cable is typically ploughed into the seabed
out to 1,000 of metres water and surface laid in deeper water (Letellier, 2004). Prior to laying, route
clearance is performed for areas that are to be buried, to remove old cables and other hazards. This
operation is known as a pre-lay grapnel run. The installation of the cable is performed by purpose-built cable
ships. Surface laying of the cable achieves between 150 to 250 kilometres per day, while burial reduces the
speed to 10 to 40 kilometres per day (Beaufils, 2000).
2.2.6. System Operation and Maintenance
Due to the time, cost and disruption to service involved in replacing submerged plant (Harasawa et al,
2008), cable systems are designed for high resilience against failure. The most common type of fault
results from physical damage to the cable from external aggression (CPNI, 2006). External aggression
relates to fishing activity, anchoring, dredging, crushing and geological activity and accounts for over 70
percent of all system faults (Kordahi et al, 2007). Components are extremely reliable and component
failure rare. Over 80 percent of external aggression faults can be attributed to human activity, with fishing
the major cause at 60 percent. The majority of external aggression faults, at 40 percent, also occur in less
than 100 metres of water. Statistical data from 2001 to 2006 shows an annual fault rate, normalised to
1,000 kilometres of cable, of 0.8 to 0.05 for depths less than 1,000 metres and 0.02-0.13 for depths greater
13
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A life cycle assessment of fibre optic submarine cable systems
than 1,000 metres (Kordahi et al, 2007). Fault protection against service disruption for transoceanic
systems can be further provided by pairing cables in a ring structure with adequate capacity and automatic
protection switching in the event of failure (CPNI, 2006). Should a fault occur in the cable, a purposebuilt cable ship must be dispatched to the localised fault area. The repair operation involves cutting and
recovery of each end of the cable, identifying and removal of the faulty section of cable and splicing in a
new section, before lowering it to the seabed again (Alcatel, 2009). In the past, cable owners generally
maintained their systems with in-house maintenance programs. However, in recent years, it is more
common to out-source maintenance operations to specialist Marine Maintenance Providers (Herron et al,
2007). Willey et al (2007) estimated that in 2007 there were 45 ships capable of undertaking submarine
cable operations.
2.2.7. End-of-Life Decommissioning
Submarine cable systems are built with a technical lifetime of 25 years, however in reality, most systems
are retired much earlier as they no longer remain commercially viable (Willey et al, 2007). Once a cable
system becomes too expensive to maintain due to age or commercial reasons, they are decommissioned.
Here, two options exist:
Firstly, no recovery is attempted and the cable remains on the seabed with no material recovery. Many
countries have requirements to remove cables from their shallow water coastal regions when retired,
though, the obligation to do so differs from country to country. When recovery is not mandatory, then
the cable owners can decide to leave the cable on the seabed or recover the cable. In most cases the cable
must be removed from within the 12 nautical mile limit (Ridder, 2007). Willey et al (2007) make an analysis
of the number of decommissioned submarine cables and noted that there is a large amount of fibre optic
cable lying on the seabed, predominantly in the northern hemisphere.
Secondly, the cable is recovered and either re-laid (e.g. for scientific use) or recycled for the materials
(Ridder, 2007). Recently, a company has considered recovery and recycling of submarine cables
commercially viable and have recovered 350km of the SAT-1 cable4 in order to recycle the steel, copper
and polyethylene (Louw, 2009). Recovery and relaying of the system for further use, however, needs
greater care to ensure that the cable is not damaged. Successful operations have been undertaken where
decommissioned systems provide donor cable for new systems giving both time and cost benefits (Merret
and Laude, 2007). Cable sections are also being re-laid to bring power and telecommunications to
underwater observatories used for scientific purposes (Lecroart et al, 2007).
4
SAT-1 is an older coaxial cable decommissioned in 1993. Recovery and recycling is assumed to be similar for fibre
optic cables. (Louw, 2009)
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A life cycle assessment of fibre optic submarine cable systems
2.2.8. Submarine verses Satellite Transmission
Submarine cables are often challenged by satellite transmission. While satellite systems are appropriate for
television and remote access, submarine networks are unsurpassed for transmitting high capacity data
traffic between countries. Submarine networks are superior in capacity, transmission quality,
confidentiality, capacity to upgrade, lifetime and maintenance, among other factors (Beaufils, 2000). A
comparison between satellite and fibre optic submarine cable communication is presented Table 1.
Table 1: Comparison between satellite and submarine cable communication (Adapted from Barattino and
Koopalethes, 2007; NEC, 2008).
Comparison Factor
Satellite
Optical Subsea
250 milliseconds
50 milliseconds
10-15 years
25 years
48,000 channels
80,000,000 channels5
$737,316 US
$14,327 US
Share of traffic: 1995
50%
50%
Share of traffic: 2008
3%
97%
Latency
Design life
Capacity
Unit cost per Mbps capacity
Thus, “owing to their high capacity, high reliability, and high signal quality, submarine cable systems are
well suited to trunk transport and backbone network infrastructure” (Beaufils, 2000, p.17).
5
Based on a system specification utilising: 10Gbps at 128WDM and 4 fibre pairs.
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3. Goal and Scope
A life cycle assessment of fibre optic submarine cable systems
3. Goal and Scope
This section describes the goal and scope of the study and details the context within which the assessment
of the environmental impacts of the studied system has been determined. The functional unit and system
boundaries are defined, along with the methodology, assumptions and limitations of the study.
3.1. Goal
The goal of this LCA is to study a fibre optic submarine cable system from a life cycle perspective to
examine the potential environmental impacts of sending data over the cable networks that span the
oceans. This study will attempt to collect as complete and up-to-date data in order to construct an LCA
model. This model will be analysed in order to identify the significant resource and energy inputs and the
subsequent emissions over the life cycle of the system. Furthermore, it will attempt to identify those
activities in the life cycle of a submarine cable that have the most significant potential environmental
impacts. This information may then be used to highlight those activities where the environmental
performance of submarine cable systems may be improved and may also be used as a link in the process
of mapping the impacts from the global ICT network.
3.1.1. Target Audience
The results of this study will be used primarily by Ericsson in their business activities, thereby making a
positive contribution in the area of environmental sustainability. However, as no previous LCA study of
submarine cables appears to have been undertaken, it is envisaged that the results will also be of interest to
other researchers in the field of environmental assessment and ICT and the submarine cable industry as a
whole.
3.1.2. Applicability of this Study
Submarine cables carry the vast majority of transcontinental voice and data traffic. The world map of
submarine cable networks (Figure 3) shows that Europe, North America and the Far East are well
connected with many cable systems spanning the oceans. The high capacity and bandwidth of these cables
makes it possible to transfer large amounts of data around the world almost instantaneously (Jonsson,
2009a). “Without sub-sea cable systems, global telecommunications at the level we know today would be
impossible.” (CPNI, 2006, p.18). Yet, little is known about the environmental impacts of a submarine
cable from a life cycle perspective (Jonsson, 2009a). Research revealed no known LCA studies in this
specific area and consequently, it appears that a knowledge gap has been identified. This study is seen as
the first step toward bridging that gap.
3.2. Scope
3.2.1. System Description
The system studied in this LCA is a generic submarine cable system utilising fibre optic cable, submarine
repeaters and land terminal stations. The system boundary is drawn at the limits of the two end terminal
stations and includes all components within the terminal to the point where the signal is transferred over
to the terrestrial network. The function of the system is to transfer large volumes of data at high-speed
around the globe. Using a cradle-to-grave approach, five phases have been identified over the 13 year life
cycle of the system; raw material extraction, design & manufacturing, installation, use & maintenance and end-of-life
decommissioning.
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A life cycle assessment of fibre optic submarine cable systems
3.2.2. Functional Unit
The function studied in this LCA is that of sending a specific amount of data over a specific length of
fibre optic submarine cable. This function has been chosen in order to evaluate the potential
environmental impact of sending data across the seabed using submarine cables given a lifecycle
perspective. The functional unit is defined as;
ten thousand gigabit kilometres
and, can be written as 10,000Gb·km. This can, for example, can be interpreted as sending 1Gb of
data over 10,000km of cable, which is approximate the average distance of sending data one way across
the Atlantic and Pacific Oceans (see Yellow/Atlantic Crossing 2 and Pacific Crossing 1 in Appendix A.
In choosing this functional unit, consideration has been given to developing a model that is scalable from
point to point. For example, should the end user of this study wish to estimate the impact of sending
telepresence data at 18Mbps (Jonsson, 2009b) between say Stockholm and New York, then the model can
be scaled by the amount of data traffic and the length of the cable between terminal stations. In this case,
the functional unit would equate to 1.25Gb of data sent over 8,000km of cable and this amount of data
would be sent every 69 seconds. To give another example; Beaufils (2000) estimates that a telephone call
consumes 85kbps, assuming the same distance, Stockholm to New York, then the functional unit would
relate to approximately 4 hours of call time.
3.2.3.
System Boundaries and Delimitations
This study considers the life cycle of a fibre optic submarine cable system from cradle-to-grave. The
boundaries begin with nature and the extraction of raw materials and end again with nature and the
emissions to soil, air and water. All significant phases, including raw material extraction, design &
manufacturing, installation, use & maintenance and end-of-life treatment have been considered for
inclusion within the system boundary, as shown in Figure 11.
Figure 11: Life Cycle stages of a submarine cable (Adapted from USEPA, 2006).
Defining system boundaries is rather subjective and needs to consider several dimensions; temporal,
geographical and technological coverage (EEA, 1997). System boundaries in this study have been selected
based principally on the theoretical framework of submarine cables systems set out in Section 2.2 and
professional experience of over 10 years working with cable systems.
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A life cycle assessment of fibre optic submarine cable systems
3.2.3.1. Temporal Boundary
The lifetime of a submarine cable system can be divided into three distinct temporal phases: the planning,
design, manufacture and installation phases of the system, today, taking approximately 18 months from
the signing of the contract (Letellier, 2004); the use & maintenance phase, where the commercial lifetime
of the cable system is approximately 10-15 years, though the cables are conservatively designed to operate
for 25 years (Beaufils, 2000); and the time horizon of a few years for decommissioning where emissions
continue to have an effect until the material recycling process is complete. Analysis of 29 retired systems
shows an average lifetime of 13 years, which is due to technological advances and capacity upgrading
making older systems expensive to maintain per unit capacity (Ridder, 2007). Thus, the low capacity
systems become uneconomic due to the high administration and maintenance costs (CPNI, 2006). In this
study, the commercial lifetime of 13 years has been considered for the use & maintenance phase, with a
sensitivity analysis undertaken for a 25 year technical lifetime scenario.
Data from the year 2000 to present day is considered to relate to the modern submarine cable system. A
list of all significant data sources and the given age is found in Appendix B. Based on the CML
methodology, no consideration is given in this report to the “temporal distribution of activities, emissions
and effects” (Guinée et al, 2004, p.42). Furthermore, while finite time horizons for future emissions from
landfills can be modelled through sensitivity analysis, this has not been explored and this problem is not
addressed in this study. Nor, has this been considered for an end-of-life scenario where the cable is
abandoned on the seabed.
3.2.3.2. Geographical Boundary
Submarine cable systems span the Earth’s oceans and, as such, have global environmental impacts. Subject
to availability, data from a number of cable systems, representing different geographical regions, has been
aggregated. It is assumed that aggregated figures will represent a reasonable estimate of the average global
impact. The vast majority of cables connect the US, Europe, Japan and China; see Figure 3. Cable and
component manufacturing plants are also located in these regions; see Appendix C – Stakeholder Analysis.
Therefore, electricity has been calculated from an equal mixture of production from the US, EU, Japan
and China as detailed in Section 4.4.1.1.
3.2.3.3. Technological Boundary
The technical boundary of this study is defined as the limits of the land terminal station; where the signal
is received from, or transmitted to, the terrestrial link. This includes the submarine cable and repeaters
connecting the terminals and all significant internal components of the terminal station such as the power
feed equipment (PFE) and the submarine line terminal equipment (SLTE), as shown in Figure 8 (Letellier,
2004). Optically amplified systems are generally designed to be upgraded without replacement of the cable
itself, achieved by upgrading to higher capacity transmission components at the terminals (Beaufils, 2000).
Current technology uses 10Gbps transmission rates with up to 64 signals on a single fibre pair (Ridder,
2007). It is assumed that cable systems installed after the millennium represent the current technical
capacity. No future scenario utilising 40Gbps technology has been considered, as the model can be scaled
linearly to account for this increase in capacity.
The inclusion of capital goods in the LCA model is a debated topic. In accounting LCAs, such as this
study, it is recommended that the study be as complete as possible and thus include capital goods. In
reality the limitations of the study, particularly time and data availability, may make this often infeasible.
(Baumann and Tillman, 2004). In this study, only the use phase of capital goods, such as buildings, cable
18
3. Goal and Scope
A life cycle assessment of fibre optic submarine cable systems
ships and other vehicles have been included, as described in Section 4 – Life cycle inventory. All other
phases of the capital goods life cycle have been excluded.
End-of-life decommissioning includes the recovery of the cable from the seabed and the recycling of
materials. A portion of these recovered materials, such as bitumen soaked polypropylene yarn, cannot be
recycled and end up in landfill (Louw, 2009). The system boundary is drawn at the landfill. Any emissions
from the landfill are accounted for in the standard GaBi software database processes. Materials entering
the landfill are described in Section 4 - Life cycle inventory.
3.2.3.4. Other Delimitations
Submarine cable system architecture is shown to consist of transoceanic repeated systems and shorter
non-repeated systems (less than 500 kilometres). Non-repeated systems do not require power to be sent
down the cable and hence do not have the copper conductor present in cable designed for repeated
systems. In order to reduce the complexity of the LCA model, non-repeated systems have not been
included in this study.
This LCA is performed to account for the significant inputs and outputs of a generic cable system and, as
such, no comparison with other methods of data transfer, for example satellite transmission, has been
attempted. The calculation of the “generic” cable system is defined in Section 6 - Calculation Procedure.
Branching units, equalisers and joints are necessary parts of the cable system (Ridder, 2007), however their
frequency is minor in relation to the overall cable length and number of repeaters. For this reason, these
components have been delimited from this study, as their potential impacts are considered to be small in
relation to the total system.
System spares are housed in depots throughout the world. These spares include different types of cable,
repeaters, jointing boxes and consumable kits for making repairs to the cable should a fault occur (Ridder,
2007). Spares have not been considered in this study, as it is assumed that their impact on the final result is
minor in relation to the total system.
3.2.4. Data Requirements and Data Quality
Throughout the study, one objective has been to collect as complete, accurate and up-to-date data as
possible on all processes within the system boundary and in the given timeframe. Another objective has
been to provide a general picture of a generic cable system given current industry practice and technology.
Cable systems are highly variable in length and level of cable protection depending on regional
characteristics. However, system components are generally similar. Where possible, data has been
collected from multiple sources to account for this variation and as far back in the processing chain as was
considered necessary. Much of the data relating to intermediate material production has been collected
from actual suppliers, though much of this is propriety information and single source, making verification
difficult. Propriety data will also reduce the transparency and reproducibility of the study, nevertheless,
this is an unavoidable limitation. Raw material extraction and refining has been estimated from processes
contained in commercial inventory databases. Where no data was available from suppliers, cable owners
or service providers, previous LCA studies, commercial databases and other literature were used to
provide a best approximation. In using data from these sources, temporal, geographical and technological
considerations were made to evaluate suitability and uncertainty. In some cases, qualified assumptions
have been made to fill data gaps and these are clearly stated in the life cycle inventory, Section 4. Data
validation was attempted on all data by comparing multiple sources (where available) and by considering
the age, location and technological relevance of the data. A list of all data sources, year and region is
presented in Appendix B.
19
3. Goal and Scope
A life cycle assessment of fibre optic submarine cable systems
Where uncertainty is considered high or a data gap exists, sensitivity analysis has been undertaken. The
results of the data quality analysis are presented in Section 7.5.
3.2.5. Methods for Inventory Analysis
The methodology for inventory analysis follows the steps of system modelling, data collection and
calculation of the environmental loads, as detailed in Section 2.1.1.2.
Firstly, the general flow chart (Figure 11) was expanded to provide more detail of the system processes
from a cradle-to-grave perspective. The flow chart sets out the hierarchical levels of the system. Two main
sub-models were identified: the cable (including repeaters) and the terminal station. Under each sub-model
the individual components were then categorised. The life cycle phases of the system were identified by
the system boundary considering a cradle-to-grave approach and modelled for each sub-model. System
modelling for a submarine cable system was based on the literature and professional experience. The
detailed system flowchart is presented in Appendix D.
Completion of the general flow chart facilitated the data collection process. Initially a broad range of data
was collected for all process within the system boundary. Then, as the collection process advanced, focus
was placed on data gaps and modelling in more detail those processes assumed to have the greatest
influence on the result. Materials having substantial weight or processes assumed to affect the result have
been included in the model. Where data was not available, inventory cut-off was applied to processes with
minimal weight and considered to have minimal environmental impact in relation to the total result.
Commercial databases from the GaBi software were used to represent raw material extraction and
processing. Where these processes were deemed insufficient to model actual material processing, an
attempt was made to contact suppliers further back in the product chain, for example, optical fibre
manufacturers. Processes that could not be found in public databases or in the literature, have been
represented by a comparable process or treated as a data gap.
A closed loop recycling process is assumed for all recycled materials at end-of-life. Closed-loop recycling
assumes that the inherent properties of the material are maintained and that the production of virgin
material is offset by the recycled material, thus avoiding the need for allocation (EAA, 2007; Giurco et al,
2006).
Calculation of the flows within, and the flows crossing, the system boundary has been facilitated by the
LCA software GaBi, explained further in Section 3.2.7. All cable related data has been normalised to 1,000
kilometres of cable within the model, in order to allow for straightforward up-scaling to the functional
unit. All terminal data has been scaled to a single terminal station. The data collection process is further
explained in Section 4.3.
3.2.6. Methods for Impact Assessment
The methodology used for impact assessment in this study follows the framework of the ISO guidelines
(ISO 14044:2006). The characterisation models are those developed by the Institute of Environmental
Sciences (CML) at the University of Leiden, in the Netherlands. This CML methodology uses a problemoriented approach that focuses on environmental problems or the so-called midpoint of the cause-effect chain
(Guinée et al, 2004). In this study ten baseline impact categories (group A categories) have been selected
using the CML 2001 characterisation database, and are detailed in section 5.2.
A submarine cable system uses significant amounts of electricity in order to power the repeaters and
terminal equipment over its lifetime. Emissions from the combustion of marine fuel are considered to
present the other major impact, in particular, having significant acidification potential (Eyring et al, 2007).
20
3. Goal and Scope
A life cycle assessment of fibre optic submarine cable systems
On this basis, three additional categories were defined in order to analyse the energy consumption over
the life cycle of the system.
Table 2: Additional categories used for the life cycle impact analysis.
Impact Category
Unit
Primary Energy
MJ
Electricity
kWh
Heavy Fuel Oil
kg
Primary energy has been modelled using the mass balance utility in the GaBi software. Parameter counters
were made within the software to track the electricity and heavy fuel oil inputs for each sub-model.
Normalisation has been undertaken to relate the characterisation results to a background, or reference
value, in order to frame the magnitude of the potential impact. This identifies if the impact is significant in
relation to the total impacts of the studied area, which may have global or regional consequences
(Baumann and Tillman, 2004). Normalisation factors used in this study are taken from Sleeswijk et al
(2008), where the annual world reference values for the emissions and consumption of the significant
substances under each impact category are collated for the year 2000.
3.2.7. Software
There are many programs available to assist the LCA practitioner with life cycle modelling (Spatari et al,
2001). The software system GaBi 46 was used for this study. GaBi is a software tool developed by PE
International and the University of Stuttgart to assist in modelling life cycle balances and analysing and
interpreting the results (PE & LBP, 2008). It has been described as one of “the top ten fully integrated and
comprehensive software tools” (Spatari et al, 2001, p82). It allows the user to assess the technical, socialeconomic and environmental impacts of a product, service or system to produce a comprehensive balance
of inputs and outputs. The software has been developed to conform to the ISO 14040 series and is built
on a modular system of plans, processes and flows. This modular system is shown in Figure 12. In
addition, standard databases are supplied with life cycle balance data for common industrial processes (PE
& LBP, 2008).
6
GaBi 4 version numbers; Compilation: 4.3.78.1, DB version: 4.126
21
3. Goal and Scope
A life cycle assessment of fibre optic submarine cable systems
Figure 12. Graphical representation in GaBi, built on a modular system (PE & LBP,2009).
LCIA can be performed using standard classification and characterisation databases, such as CML2001
(Guinée et al, 2004) and Eco-indicator 99 (Pre, 2000). However, it is also possible to enter environmental
indicators manually (Bergelin, 2008).
3.2.8. Study-Wide Assumptions, Simplifications and Limitations
A life cycle assessment study requires a significant effort in collecting and analysing large amounts of
environmental and product data. As the whole life cycle is studied, the complexity of a system makes it
impossible to model every detail (Baumann and Tillman, 2004). As such, the LCA model is a
simplification of reality and this is important to remember when interpreting the results (3GLCA, 2002).
This section describes the central assumptions, simplifications and limitations of this study.
This LCA has been undertaken to assess the potential impact of a generic submarine cable system. As
such, data has been taken from many sources covering different regions, yet the results are intended to
represent an average cable for any geographic region. Where only single source data was available, it is
assumed that this is representative of the generic process. Single source data raises the uncertainty of the
result as verification is not possible for this data. An unavoidable limitation is the use of propriety data.
This reduces the transparency and reproducibility of the study as the data remains confidential (Baumann
and Tillman, 2004). Whenever propriety data has been used, it is clearly stated in the LCI, Section 4.
Detailed confidential data has not been presented in the LCI section, however, this has not restricted the
presentation of the final result.
Energy use appears to be the largest contributor to the environmental impacts. Electricity production has
been simplified to four differing geographical regions and these are assumed to represent a realistic
electricity mix for the purposes of this study. Heavy fuel oil (HFO) production has been modelled from an
22
3. Goal and Scope
A life cycle assessment of fibre optic submarine cable systems
equal mix of US and EU production. As no other data for HFO production could be sourced in the given
timeframe, it is assumed that this simplified model is representative of world production. However, this
data will be biased toward production methods in the EU and the US.
All transportation of raw materials is assumed to be undertaken overland at an average distance of
1,000km. All transportation of wastes and recycled materials are assumed to be undertaken overland at an
average distance of 100km. Given the doubt in these assumptions, a sensitivity analysis has been
undertaken for each process in order to evaluate the impact on the result. Further details of these
assumptions are presented in Section 4.4.2 - Transportation. The results of the sensitivity analysis are
presented in Section 7.5.1.
This study uses data supplied by Ericsson for the production of submarine cable. It is assumed that the
manufacturing process is representative of all cable manufacturers. However, Ericsson does not produce
cable for the repeated systems that use additional materials, in particular the copper conductor. Therefore,
the mass of each material per unit length of cable has been scaled from the cross-sectional area of cable
designed for a repeated system. This induces a level of uncertainty, though the resulting total mass per unit
length was in good agreement with the documentation and therefore, it is concluded that the result is not
affected.
Data for the raw materials and manufacturing processes of the terminal equipment and submarine
repeaters could not be sourced given the time limitations. This presents the largest data gap in the study.
Assumptions have been made based on total weight and what are assumed to be equivalent processes
from available data, as detailed in Section 4. This, naturally, induces a high level of uncertainty for these
two sub models and was considered to be a significant limitation of this study. However, the sensitivity
analysis (detailed in Section 7.5.1) shows that the results are not significantly affected by the uncertainties
in these two sub-models.
The end-of-life scenario assumes a recovery rate of 100 percent for the mechanical materials (Louw,
2009). It is assumed that these materials are recycled in a closed-loop process and offset 90 percent of the
virgin material input. The remaining 10 percent is assumed to be lost from the system during the recovery
and recycling process. No attempt has been made to account for this material as emissions. A sensitivity
analysis has been undertaken to explore the effects of these recycling assumptions on the result, see
Section 7.5.2.
The capacity and usage calculation for the generic cable system (i.e. how many gigabits are sent annually) is
based on 11 systems built between 2000 and 2006 (detailed in Section 6). This places a limitation on the
applicability of the results to today’s 10Gbps technology. However, terminal station technology is rapidly
developing and commercialisation of 40Gbps transmission is fast approaching (Ishida et al, 2007). In
theory, this will reduce the environmental impacts per unit of data further as a greater amount of data can
be sent down the same cable. Future scenarios based on greater capacity can be modelled by scaling of the
results relative to the capacity calculation presented in Section 6.
Validation of the result against an actual system, is not possible in this case, due to the complexity and
geographical dimension of a submarine cable system.
When interpreting the results, it is important to take into consideration that the analysis has been
undertaken given a 13 year commercial lifetime of the cable (Ridder, 2007). It is shown that the technical
lifetime of the cable is significantly longer, at 25 years (Beaufils, 2000). This has been addressed in the
sensitivity analysis, where a scenario based on the average technical lifetime is explored.
23
3. Goal and Scope
A life cycle assessment of fibre optic submarine cable systems
3.2.9. Critical Review Procedure
Critical review of the study is necessary in order to verify that the “LCA has met the requirements for
methodology, data, interpretation and reporting and whether it is consistent with the principles” of LCA
(ISO 14040:2006, p17). As defined in the ISO standard (ibid), both internal and external experts with
appropriate scientific and technical expertise have supervised this study and provided review and guidance
respectively, Fredrik Jonsson of Ericsson and Åsa Moberg of The Royal Institute of Technology (KTH).
Further, a review of the report structure has been undertaken by a panel of interested parties (ISO
14040:2006) during the presentation and defence of this study at KTH.
24
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
4. Life Cycle Inventory (LCI)
This section describes the system and the process of data collection and calculation. Furthermore, a
detailed description is given of the structure of the core sub-models for the life cycle inventory.
4.1. Description of System
This study is undertaken on a generic fibre optic submarine cable network, where the system boundary is
drawn at the limits of the two end terminal stations to the point where the signal is transferred over to the
terrestrial network. This includes all cable and repeaters used for the subsea link between terminals and all
transmission and receive components within the terminal station itself. Each component is further
explained in the theoretical framework, Section 2.2.4.
The LCA model has been assembled within the GaBi software. The model has been constructed to
account for all significant material and energy inputs and subsequent emissions from the system. Two
main sub-models have been developed: one based on the submarine cable and associated repeaters; the
other, on the land terminal station. This gives the model greater versatility in assessing the potential
environmental impacts of a particular repeated submarine cable system as the model can be scaled by the
length of cable and the number of terminal stations. For this study, a definition of the generic cable
system has been established based on the literature and is presented in Section 6.
Using a cradle-to-grave approach, five phases have been identified over the life cycle of the system; raw
material extraction, design & manufacturing, installation, use & maintenance and end-of-life decommissioning. The five
phases are represented by LCI sub-models defining each progressive life cycle process and are further
divided into cable and terminal station processes. The basic structure of the life cycle model is shown in
Figure 13, with a detailed system flowchart presented in Appendix D.
RAW MATERIAL
EXTRACTION
DESIGN &
MANUFACTURING
INSTALLATION
USE &
MAINTENANCE
END-OF-LIFE
DECOMMISSIONING
CABLE
LW cable
LWP cable
SA cable
DA cable
Subsea repeater
CABLE
Route Survey
LW cable
LWP cable
SA cable
DA cable
Subsea repeater
CABLE
Cable ship modes
Transit
Manoeuvring
In port
CABLE
Cable ship modes
Transit
Manoeuvring
In port
Cable energy use
CABLE
Recovery by ship
Material Recycling
Cable
Repeater
TERMINAL
PFE
SLTE
Lead acid battery
Back-up generator
TERMINAL
Desktop Study
PFE
SLTE
Lead acid battery
Back-up generator
TERMINAL
No process
TERMINAL
Energy use
TERMINAL
Material recycling
Lead Acid battery
Printed board
assembly (PBA)
Figure 13: Basic structure of the life cycle of a submarine cable system.
The raw material extraction phase defines the materials required for the cable, repeaters and terminal
equipment. Further sub-sets model each type of cable, a submarine repeater and the terminal components
in more detail. Transportation of the raw materials is accounted for in the sub-models.
The design & manufacturing phase defines the processing of raw materials into the final products ready
for installation. Manufacturing of the cable, a submarine repeater and the terminal components are
25
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
modelled. Consumed energy and wastes from the manufacturing process are accounted for in the submodels.
The installation phase accounts for the at-sea installation of the cable by purpose-built cable ship.
Repeaters are installed with the cable and are accounted for in the cable sub-model. Terminal station
installation is assumed to have a minor impact on the result and is not modelled.
The use & maintenance phase accounts for the energy consumed by the terminal station and the cable
itself, and, the at-sea maintenance of the cable by cable ship. This phase represents the significant process
of the life cycle with respect to time. Given the 13 year use & maintenance period, this phase is assumed
to have the greatest impact on the results.
The end-of-life phase is modelled on a scenario of cable recovery and material recycling. Cable recovery is
undertaken by cable ship and is assumed to be the reverse process of installation, therefore, utilising the
same resources. Cable material recycling is based on the main mechanical materials in a closed-loop
recycling process. The recycling processes for each material are simplified models based on the
documented energy consumption during material reprocessing. Recycling of the terminal materials has
been considered for the lead-acid batteries and the printed board assembly (PBA). No other end-of-life
processes are modelled for the terminal station.
4.2. Data Calculation
All collected data has been input into the GaBi software to enable the relative scaling of each process
within the sub-models and in relation to the reference flow of the functional unit. “The calculation result
is a set of linked and scaled processes” with resulting scaled environmental impacts (Guinée et al, 2004,
p.60).
4.3. Data Collection Process
Data has been collected from a variety of sources within the scientific community and companies linked
to the cable industry.
The theoretical framework has been established from the ISO 14040 series guidelines for LCA, published
journal articles, books and reports. Articles from scientific journals were searched through the online
KTH library portal. Databases such as, Highwire Press, Science Direct, Scopus, SpringerLink, Web of Science and
Wiley InterScience, were searched firsthand, with a more general search of the internet through Google and
Google Scholar. Articles and reports collected through the general internet search have been validated by
checking the author’s credentials and the source of the data. The literature is presented in two categories;
the methodology of LCA and the description of a submarine cable system. For the LCA methodology,
preference was given to the ISO standard (ISO 14040:2006), peer reviewed journal articles and LCA
handbooks such as Baumann and Tillman (2004) and Guinée et al (2004). For submarine cable systems,
preference was given to journal articles, however these were fewer and industry reports and company
websites provided additional valuable information.
The goal and scope definition is based on the ISO 14040 series guidelines and LCA handbooks.
System modelling and identification of data requirements was based on the theoretical framework and 12
years of professional experience working with submarine cable systems. While professional experience can
be considered subjective, it provided a starting point for the literature search and many leads through
contacts within the industry. A stakeholder analysis was undertaken to identify possible contacts within the
industry, attached in Appendix C.
26
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
Data for the raw materials and manufacture of the cable was collected from Ericsson Network
Technologies (Ericsson Cables) and their suppliers. A site visit was made to Ericsson’s Hudiksvall cable
manufacturing plant in order to gain a clearer understanding of the cable production process. A meeting
was held with four Ericsson representatives there, leading to email contact with their suppliers. A
questionnaire was sent out to these suppliers with the aim to collect data relating to the material and
energy consumption, transportation and wastes from their products. The questionnaire did not cover
specific site emissions. All suppliers were given the same questionnaire containing semi-structured
questions, which resulted in open answers and statistical data. The questionnaire is attached in Appendix
E.
Data collection for terminal equipment and submarine repeaters has proven to be more problematic and
has resulted in a data gap. The four known manufactures of these components were contacted and invited
to participate however, no company was willing to disclose commercially sensitive proprietary
information. As such, estimates of these processes, based on similar processes from the literature, have
been necessary to fill the data gap. Data from previous LCA studies at Ericsson, published articles and
other industry reports have been used to fill the data gaps and approximate the terminal and repeater
processes. The effect of this substitution is explored in the sensitivity analysis in Section 7.5.1. Standard
database processes supplied with the GaBi software have been used to model the raw material processing,
energy production, transportation and waste handling. Additional information on system processes has
been gained by email and phone conferences with professional contacts within the cable industry.
Confidential proprietary operation reports have been used to estimate activities for the cable design,
installation and use & maintenance phases. The details of these reports are not presented in this study,
however this does not affect the presentation of the final result. Published articles and reports have
provided further data, particularly in the area of emissions from ships and material recycling.
A site visit was made to a cable terminal station in Auckland, New Zealand. A walk around and open
discussion with two Telecom New Zealand representatives provided a greater understanding of the
components that make up a terminal station. Notes were taken during this session which were later
verified against the literature and used to develop the terminal station sub-model.
This study was also partially completed at sea during a 4800 kilometre cable route survey. Data collected
during this period relates to the design sub-model, and includes data on Research vessel operations, fuel
use and cable routing. This data is also considered confidential and full details are not presented in this
report. Again, this does not affect the presentation of the final result.
Characterisation factors and impact categories based on the CML methodology for LCIA (base year 2001)
have been used directly from the GaBi software database.
For details of the data used in this study, refer to Section 4.4, Description of Core Unit Operations and LCI SubModels and Appendix B.
The data collection period was approximately 5 months.
4.4. Description of Core Unit Operations and LCI Sub-Models
This section defines of the structure of the core sub-models for the life cycle inventory (LCI) of the
submarine cable system. Modelling for energy production, transportation, raw material extraction, design
& manufacturing, installation, use & maintenance and end-of-life decommissioning are described in detail.
27
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
4.4.1. Energy
4.4.1.1. Electricity Generation
The vast majority of cables connect the US, Europe, Japan and China, see Figure 3 – World map of
submarine cables. Based on the stakeholder analysis, cable and component manufacturing plants are also
shown to be predominantly located in these regions. The environmental impact of electricity generation
has therefore been calculated from an equal mixture of production from the US, EU, Japan and China
(25% per country). It is assumed that this provides an average mix relevant to cable manufacture and
utilization. The impacts of electricity generation for each country have been adopted from two previous
studies at Ericsson. Chinese production has been model by Bergelin (2008) from the base years of 2003 to
2006. Figures for CO2, SO2, NOX and PM10 (dust) were calculated from published data relating to the
environmental load cost in US dollars per kilowatt hour (kWh). This was converted to actual emissions
per kWh based on total environmental cost and total electricity production. All other emissions for
electricity production in China were estimated from published US results, having the second highest
electricity from coal production at 51 percent compared to China at 80 percent. Some uncertainty exists in
this data. Further details of the method of calculation, assumptions and simplifications, can be found in
Bergelin (2008). The impacts of production in the US, EU and Japan were modelled during an extensive
LCA into the impacts of a Third Generation (3G) mobile telephone system undertaken at Ericsson.
Included in the electricity model was generation from fossil fuels, nuclear fuel and hydro plants.
Furthermore, the whole supply and distribution chain was considered, including, distribution to industrial
consumers, production and transport of fuels, materials consumption and construction of generation and
distribution facilities. Generic production models were adapted to local conditions by applying each
region’s statistical fuel base for percentage production from coal, gas, oil, nuclear and hydro, using base
years between 1994 and 1999, as shown in Table 3 (3GLCA, 2002). The effect on the results of the
uncertainty in the electricity data as a whole is explored in the sensitivity analysis in Section 7.5.2.
Table 3: Distribution of electricity generation processes (Adapted from 3GLCA, 2002; Bergelin, 2008)
Region
Total Generation TWh/year
Coal %
Gas %
7
Oil %
U
8
Nuclear %
U
8
Hydro %
U
Other
8
U8
China (2003)
1580
80
U
Europe (1994)
1605
28
10
10
37
14
1
Japan (1994)
1027
15
26
10
36
11
2
US average (1999)
3728
51
16
3
20
8
2
Other sources of generation, such as, geothermal, biomass, wind and solar were not modelled. Further
details of the method of calculation, assumptions and simplifications, can be found in (3GLCA, 2002). No
attempt has been made in this study to update these figures.
In determining the energy count, the GaBi software does not distinguish between primary energy and
secondary energy, such as electricity. Based on the previous work of Bergelin (2008), a parameter was used
to count all electricity (secondary energy) used within each sub-model. Consequently, for each unit of
secondary energy, the primary energy needed to produce it, can then be analysed. Based on the electricity
mix used for this study, a total of 13.7megajoules (MJ) primary energy is needed to produce 3.6MJ of
electricity, giving a secondary to primary energy factor of 3.81. Electricity used for the standard database
processes within the GaBi software cannot be extracted from primary energy.
The reference flow for the electricity sub-model is 1 kWh.
7
U = unknown, though it is assumed that the majority of the remaining 20% comes from hydro. (Bergelin, 2008)
28
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
4.4.1.1. Heavy Fuel Oil
The environmental impact from the production of heavy fuel oil (HFO) has been modelled using standard
database processes available in the GaBi software. A 50/50 mix of United States (US) production and
European Community (15 countries - EU-15) was constructed to provide an approximate world mix of
HFO at the refinery. Though, it must be kept in mind that this sub-model is biased toward US and EU-15
production. Data from other countries was not available. Transportation from the refinery to the port
where bunkering may take place has not been considered. It is assumed that the HFO sub-model
represents the production of residual oil (RO) fuels used for marine transportation, described further in
Section 4.4.2.1.
The reference flow for the HFO sub-model is 1kg.
4.4.2. Transportation
The transportation sector is a major contributor to pollution and a significant fact in anthropogenic
climate impacts. Fossil fuel combustion still dominates the freight transportation sector. Heavy-duty truck,
rail and water transport combined account for over 25 percent of CO2 emissions for all mobile emission
sources in the US and over 30 percent in the EU (Corbett and Winebrake, 2007). In this study, it is
assumed that transportation of the raw materials or products used for cable manufacture and the wastes
and materials for recycling is undertaken overland by long-distance 34-40t truck and trailer.
Transportation of the manufactured cable is always undertaken by sea route due to the sheer weight and
bulk of a completed cable. Personnel transfers requiring international air travel to and from the ships, has
been modelled to evaluate the effects from aviation in relation to the total result. No rail transportation
has been modelled in this study.
4.4.2.1. Marine Transportation
Ships, naturally, play a key role in the design, installation and maintenance of submarine cable systems
during their life cycle and, as such, much focus has been placed on the methodology for estimating
emissions from ships. Commercial shipping makes a significant contribution to global air pollution (Lack
et al, 2009). Emissions from ships engines are among the highest polluting sources per ton of fuel (Corbett
and Koehler, 2003). It is estimated that 2.7% of anthropogenic CO2 emissions in 2000 were from
shipping, contributing significantly to total emissions from the transport sector (Eyring et al, 2007). Studies
show that air pollutants from ships are related to three factors; engine type, engine loads and fuel type
(CARB, 2008; Cooper and Gustafsson, 2004; Corbett and Koehler, 2003, European Commission, 2002).
Installed engine power is the important factor for estimating emissions, rather than the number of engines
(Corbett and Koehler, 2003). Generally, ships have a main engine (ME) used for propulsion and auxiliary
engines (AE) used for electricity generation. MEs and AEs can be further classified based on their speed
measured at the crankshaft, another factor affecting emissions. Emissions from boilers, emergency
engines and other equipment are small in comparison and can generally be excluded. Fuel types, classified
by their viscosity, range from light marine distillates (MDs) to heavier residual oils (ROs). Some emissions
are directly related to the content within the fuel, particularly sulphur. (Cooper and Gustafsson, 2004).
While other emissions such as nitrogen oxides (NOx) are related to the type of combustion system
(Corbett and Fischbeck, 1997). MDs are considered to have fewer impacts both from an environmental
and economic standpoint (Fet, 2009). Three operational modes are identified, each having a differing
effect on the engine load and the combustion efficiency of the fuel; transit, manoeuvring and in port. ME
emissions occur during transit and, to a lesser extent, manoeuvring and AE emissions during all modes. At
cruise speed, the ME load is estimated at 82.5 percent. Vessels generally do not cruise beyond this load
rating as fuel consumption and maintenance increase significantly (CARB, 2008; Cooper and Gustafsson,
2004). Manoeuvring load factors are estimated at lower and varying loads. Auxiliary engine load factors are
29
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
estimated at 50 percent. Manoeuvring and in port emissions are relatively small in relation to transit
emissions, though equally important as they occur close to populated areas. Emissions have been based on
the Cooper and Gustafsson (2004) study, as a larger number of pollutants are accounted for when
compared to similar studies. They conclude that, at the time (base year 2002), the emission factors
presented were an “up to date and “best possible” estimate” for Swedish sold fuel (Cooper and
Gustafsson, 2004, p32). Many of the emissions factors have high uncertainty ratings based on the
assumptions and availability of data. Emission factors are tabulated in Cooper and Gustafsson (2004). It is
assumed that emissions from Swedish fuel are representative of emissions from other developed nations.
This assumption has been verified against two other studies into shipping emissions by the European
Commission (2002) and the California Air Resources Board (CARB, 2006), with good correlation. It
should be noted that each study uses the same methodology for estimating emissions with similar results
given the temporal and regional differences in the inventory datasets; California - base year 2006 (CARB,
2006) and Europe – base year 2000 (European Commission, 2002). The latter was regarded “as the most
comprehensive published test data for commercial marine vessels.” (Corbett and Koehler, 2003, p9-2).
Further verification was undertaken by Corbett (2004), concluding that good correlation exists between
estimated values and stack test results, with in-plume observations having greater uncertainty due to
complex chemical processes. Furthermore, the emission factors calculated by Cooper and Gustafsson
(2004) show good correlation to actual emission rates (single vessel observation) and the Lloyd’s Marine
Emissions Research Programme test data (Corbett, 2004).
As nitrogen oxide (NOX) reduction techniques are only common in newer vessels (Cooper and
Gustafsson, 2004), reduced emission factors have not been considered. Table 4 presents emission factors
for the most significant pollutants from marine diesel engines, full emission factors are tabulated in
Cooper and Gustafsson (2004). Emission factors for residual oil (RO) and slow speed diesel engines have
been used in this study as they represent the majority of fuel used and engine type in commercial shipping
(Corbett and Fischbeck, 1997). It should be noted that RO has exceptionally high sulphur and particle
matter (PM) emissions (Corbett and Winebrake, 2007). The process for the production of heavy fuel oil
(HFO) was used from the GaBi software, which is assumed to represent the production process of RO
fuel.
Table 4: Selected engine emission factors (g/kWh) for Residual Oils (Cooper and Gustafsson, 2004).
Engine Type
Engine
Speed
Operation
Mode
Fuel
NOx
CO
SOx
PM10
PM2.5
CO2
CH4
Main Engine
Slow
At Sea
RO
18.1
0.5
9
1.3
1.3
620
0.006
Main Engine
Slow
Manoeuvring
RO
14.5
1.0
9.9
2.6
2.6
682
0.012
Aux. Engine
Medium
In Port
RO
14.5
0.9
10.4
0.5
0.5
722
0.004
Manoeuvring loads are assumed to compare with the operational phase of cable route survey and
installation. Main engine manoeuvring loads are assumed by Cooper and Gustafsson (2004) at 20 percent.
This is likely to be an under estimation, as the ship’s engines are likely to be under greater load. However,
review of the emission factors shows that the emissions are greater for manoeuvring, in relation to “at
sea” emissions, in all categories except NOX emissions with are reduced by 20 percent. Therefore, it is
assumed that this does not affect the results significantly. Table 5 shows the load characteristics during
each operation mode.
30
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
Table 5: Average Cable Ship engine load characteristics by operational mode. (Cooper and Gustafsson, 2004)
Operation Mode
Transit
Manoeuvring
In Port
Main Engines
80%
20%
0%
Auxiliary Engines
50%
50%
50%
The construction of ships is not included in this study. It was intended to expand the system boundaries
to include the construction of the purpose-built ships used to install and maintain the cables. While there
have been many studies relating to the construction of ships, specific data could not be sourced. However,
previous studies in the area indicate that the use phase totally dominates the environmental impacts due to
the emissions created from fuel combustion (Ellingsen et al, 2002; Fet, 2003; Fet et al, 1996; Lingg and
Villiger, 2002). The construction phase of a ship’s life cycle has been estimated to have one hundredth
(100th) of the impact of the use phase; therefore, limiting the study to the operating phase is considered
sufficient (Fet et al, 2000). Steel scrapping and recycling at end-of-life has been shown to compensate for
over 80 percent of virgin material input and reduce other emissions (Fet, 2003). Although, Ms. Fet did
advise in personal communication that this was a rudimentary LCA study with inherent uncertainty.
Local and regional impacts result from the maintenance of ships, where hulls are typically sand blasted and
repainted with antifouling. Antifouling coatings are the paint used on the hull of the ship to inhibit marine
growth and hence, release a number of pollutants to seawater. An estimation of the impacts due to hull
maintenance activities has been calculated during one LCA study completed for a Platform Supply Vessel
servicing the oil fields between Norway and the United Kingdom (Fet et al, 1996). It is assumed that this
vessel type is comparable to the typical cable ship. Though, uncertainty is high given that this is a single
case study, some years old and based on regional practice (Norway).
4.4.2.2. Road Transportation
Transportation of the cable materials is undertaken in two stages, firstly, raw material transportation to the
intermediate processing factories, secondly, transportation of the intermediate products to the cable
manufacturing plant. Cable manufacture has been modelled based on the processes at Ericsson cables in
Sweden. Data relating to transportation distances for materials and intermediate products have been
collected from Ericsson cables and their suppliers. Based on this data and that the intermediate materials
used in cable manufacture are generally specialised items made by few suppliers, a distance of 1,000km is
assumed for all materials road transportation. It is assumed that this distance is relevant for all cable
manufacturers irrespective of geographic location. For waste treatment and the recycling scenario, road
transportation has been estimated at 100km. Louw (2009) advises that materials for recycling are
transported over a radius of 30 kilometres. It is there assumed that a 100 kilometre radius for
transportation of waste and recycling materials is a reasonable estimate. Road transportation processes,
modelling production (diesel at refinery) and combustion of fuel (truck by gross tonnage), have been used
from the GaBi4 database. Other elements, such as, road infrastructure, vehicle manufacture, vehicle
maintenance and fuel handling, have not been included. A sensitivity analysis has been undertaken to
determine the effect on the final result of both road transportation assumptions and is presented in
Section 7.5.1.
4.4.2.3. Air Travel
“Personnel-related environmental impact is usually not included in LCA” (Baumann and Tillman, 2004,
p82). Exclusion may be justified if the impacts are considered small, however, transportation of personnel
to and from the workplace can be significant (USEPA, 2006). Air travel is considered likely to have a
31
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre
e optic submarine cable systems
internatio air travel
noticeable environmental impact,, as personnel transportation involves substantial international
to and from the ships. Therefore,, air
air travel is calculated based on the input and emissions for one person
kilometre travelled (1pkm) determined from previous studies at Ericsson.
Ericsson Thee Ericsson study shows that,
1pkm uses 1.6MJ of primary energy
ene
and, among other emissions, releases 120 grams of carbon dioxide
into the atmosphere (3GLCA,
3GLCA, 2002:
2002 LCA database).
4.4.3. Raw Material Extraction Phase
The sub-model
model for the extraction of raw materials begins with the extraction of the materials
ma
from the
environment, includes the processing
ssing of these materials into their respective products (such as aluminium
ingots) and ends with the transportation of the materials to the assembly site. The sub-model
sub
is further
divided into the three main components of a submarine
submarine cable system; the cable, submarine repeaters and
the terminal station. Database processes from the GaBi software have been used to model the extraction
and processing of raw materials.
4.4.3.1. Cable Raw Materials
Data for the cable raw materials has been collected from Ericsson Network Technologies (Ericsson
Cables) and calculated from other confidential cable specifications.
specifications A full list of data sources can be found
in Appendix B.
The four primary cable types were chosen to represent the generic system; Lightweight (LW), Lightweight
Protected (LWP), Single Armour (SA) and Double Armour (DA), as shown in Figure 9. Cable systems use
a variety of these cable types with a corresponding variance in material use directly tied to the amount of
steel wire armour protection provided. The link between steel armouring and total cable weight is shown
in Figure 14.
9000
8000
kg per 1000m
7000
6000
5000
4000
Steel
3000
Total
2000
1000
0
LW
LWP
SA
DA
Cable Type
Figure 14: Total weight verses weight of steel per 1,000 metres of cable.
cable
In order to normalise the use of each cable type to 1,000
1
kilometres of cable, four submarine systems
representing a total of over 40,000km
0km of cable, were analysed
ysed and the ratio of each cable type determined
(shown in Table 6). This ratio was then applied to the raw materials sub-model
model for each cable type and
combined to give the resulting raw material usage for 1,000 kilometres.
32
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre
e optic submarine cable systems
Table 6: Ratio of cable types in the generic system.
LW
LWP
SA
DA
70%
14%
13%
3%
proc
within
All significant materials used in the cable have been accounted for and are represented by processes
the GaBi software. Figure 15 shows the distribution of all other materials
materials (excluding steel) by cable type,
which illustrates how the cable armouring is built around the core of the fibre unit structure (stainless steel
tube filled with gel and fibre), the surrounding copper conductor and the high-density
high
polyethylene
insulating plastic. It also highlights the dominance of the main mechanical materials.
500,00
450,00
400,00
kg per 1000m
350,00
300,00
LW
250,00
LWP
200,00
SA
150,00
DA
100,00
50,00
0,00
LW: Lightweight, LWP: Lightweight Protected, SA:
SA Single Armour,
r, DA: Double Armour
Figure 15: Distribution of all other raw materials (excluding steel) by cable type.
No data could be sourced for the production of high quality optical fibre. Purifying and drawing the fibre
uses significant amounts of energy (Corning,
(
2008). The
he GaBi database process for glass fibres (for
composites materials) was used to provide an approximation of the process. It is assumed that this does
not affect the results greatly as fibre represents 0.3% of the total weight of the lightweight cable. All other
processes and materials are well defined in the GaBi software database.
The reference flow for the sub-model
model is 1,000km of cable.
33
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
4.4.3.2. Submarine Repeater: Raw materials
Specific data for the submarine repeaters could not be sourced, therefore assumptions are necessary. Data
for the repeater raw materials has been defined by the weight of the housing with the remaining materials
assumed from similar processes based on previous studies at Ericsson Research. The total weight of the
repeater itself is given as 255 kilograms, including cable terminations, the total weight is 459 kilograms and
the weight of the housing alone is given at 170 kilograms (confidential source). It is assumed that the
repeater housing is made from beryllium copper (BeCu) alloy. No process for the extraction of beryllium
was available in the standard databases, however, BeCu alloys used for submarine repeaters contain
typically 98% copper, 1.7% beryllium an 0.3% cobalt (Davis, 2001). Therefore for this study, it is assumed
that the housing is made of 100 percent copper.
The remaining internal components and cable terminal materials have been estimated based on an
apportioned weight distribution. Previous studies at Ericsson have been used to model these components.
The Ericsson 3G mechanical enclosure study (MECH, 2001) was used to provide the reference for the
mechanical materials. The printed board assembly (PBA) model constructed during the Ericsson LCA
study into a 3G mobile network has been used to estimate the electronic components within the repeater
(3GLCA, 2002; PBA,2001). The total weight of the internal components is estimated to be 85 kilograms.
Based on experience at Ericsson, the PBA weight to mechanical weight ratio of the sub-racks has been
estimated at 10 percent (Malmodin, 2009), thereby resulting in a PBA weight of 8.5 kilograms. The
mechanical enclosure model has been used to estimate the processes for the remaining 280.5 kilograms.
Naturally, these assumptions introduce significant uncertainty for this sub-model.
The reference flow for the sub-model is 1 repeater unit. It is assumed that repeaters are placed every
50km, requiring 20 units per 1,000km of cable.
4.4.3.3. Terminal Equipment: Raw materials
Specific data for terminal station equipment could not be sourced, therefore assumptions are necessary.
Data for the terminal raw materials has been defined by confidential terminal station specifications (year
2000) and assumed from similar processes based on previous studies at Ericsson Research. Four submodels were created to account for the back-up batteries, the power feed equipment (PFE), the
submarine line terminal equipment (SLTE) and the back-up generators. A full list of data sources can be
found in Appendix B.
Figure 16 shows the distribution of components by weight in the terminal station.
34
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre
e optic submarine cable systems
9000
8000
7000
6000
kg
5000
4000
3000
2000
1000
0
Lead--Acid
PFE
SLTE
Generator
PFE: Power Feed Equipment, SLTE: Submarine Line Terminal Equipment
Figure 16: Distribution of raw materials in the terminal station.
The lead acid battery materials were provided by a previous Ericsson cradle-to
to-gate study for the
manufacturing of a two volt (2V) cell used in a radio base station (Pb-Battery, 2001).. Terminal stations use
lead acid batteries to supply approximately 50V DC power in the event of a power failure. Four battery
banks were observed during a visit to one terminal station. It is assumed that this is common
commo for terminal
stations. The reference flow for the sub-model
sub
is a 2V cell, thereby utilising 100 2V cells.
The power feed equipment (PFE
PFE) specification was determined from both confidential sources and
published sources (Alcatel, 1998),, and is assembled from LCA studies of similar products undertaken
undertak by
Ericsson and ABB (ABB, 2009a; ABB, 2009b; ABB,
ABB 2009c).. The PFE comprises direct current (DC)
converters, monitoring equipment and mechanical enclosures (cabinets). Terminals have two parallel
systems to provide protection against failure in any one system (Alcatel, 1998). Based on the literature, a
total of 20 kilowatt DC converters and 4 monitoring modules were estimated. This allows for two 10kV
PFE systems operating at approximately one ampere (1A).. Material specification for the cabinets has been
taken from a previous Ericsson cradle-to-gate
cradle gate study for the mechanical enclosure for a third generation
(3G) mobile system. It was determined that 97 percent of the materials were accounted for in the study
(MECH, 2001). It is assumed that the materials used in the 3G cabinets are similar to those used in the
terminal station. A total of five cabinets each with
wit a weight of 80kg have been estimated.
estimated The weight of
the cabinet was comparable in Ericsson documentation at 75kg (Characteristics
acteristics Specs,
Specs 2009). The
reference flows for the sub-model
model are; 1 kW equivalent per DC converter (total 20kW), one monitoring
unit (total 4) and weight of mechanical enclosure (total 400kg).
400
The submarine line terminal equipment (SLTE)
(
equipment includes
des the various components needed to
generate and manage the light wave signals. Materials for the SLTE equipment are based on the
specification of a single terminal station and the floor plan showing the layout of a second. A
diagrammatic layout of the SLTE is shown in Figure 17.
35
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
SDH:
Synchronous Digital Hierarchy
HPOE: High Precision Optical Equipment
LME:
Line Monitoring Equipment
WTE:
Wavelength Terminating Equipment
TLA:
Terminal Line Amplifier
Figure 17: Diagram of Submarine Line Terminal Equipment (SLTE) (Adapted from Markow, 2009).
Weights for each cabinet and sub-rack where provided in the terminal documentation, however no
detailed data was available for the actual electronic boards themselves. Again, previous studies at Ericsson
have been used to model these components. The Ericsson 3G mechanical enclosure study (MECH, 2001)
was used to provide the reference for the mechanical materials. The printed board assembly (PBA) model
constructed during the Ericsson LCA study into a 3G mobile network has been used to estimate the
electronic components within the sub-racks (3GLCA, 2002; PBA,2001). Based on experience at Ericsson,
the PBA weight to mechanical weight ratio of the sub-racks has been estimated at 10 percent (Malmodin,
2009). A total of four fibre-pairs with 16 light wave signals have been assumed for the generic system.
This provides a total capacity of 64 wavelengths and equates, based on the above assumptions, to 30
cabinets with 79 sub-racks. Estimated weights are presented in Table 7. The abbreviations are explained in
Section 2.2.4.3.
Table 7: Estimated weights of terminal components.
Component
SDH
(kg)
HOPE
(kg)
WTE
(kg)
TLA
(kg)
LME
(kg)
Total
Cabinets (80kg unit)
320
1280
640
80
80
30 units
Sub-Rack Equipment
224
3328
448
74
56
79 units
Total Mechanical Sub-Racks (90%)
202
2995
403
67
50
Total PBA Equipment (10% of Sub-Rack)
22
333
45
7
6
413kg
Total Mechanical (Cabinets + Sub-Racks)
522
4275
1043
147
130
6117kg
The PBA components of the sub-racks calculate at 413kg and the mechanical materials at 6177kg, giving
6.8% PBA weight to total mechanical weight. These figures are used to construct the model for the
terminal station SLTE. However, they come with high uncertainty and are likely an over-estimation, due
to the uncertainty of the weight of the PBAs and the age of the terminal specification (taken from year
2000). System upgrading adds further uncertainty due to the refinement of electronics. Upgrading, in most
cases, makes savings in both volume and mass. The results from an LCA of a personal computer
(Williams and Sasaki, 2003) provide the estimate for the Network Management Equipment (NME).
Upgrading must also be considered with regard to material inputs. Over the 13 year life cycle of cable
system, it is estimated that 3 upgrades will undertaken (Betts, 2009; Veverka, 2009). In each case the
capacity of the cable is increased by replacing only the electronic equipment of the terminal. Therefore,
36
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
the PBA and the NME inputs for have been scaled by a factor of three in the terminal model to provide a
linear approximation of the upgrade process. This is a simplification for the purposes of this study and
does not account for the gains in equipment efficiency or the temporal variation of each upgrade. The
effect of this simplification on the results is explored in the data quality analysis is Section 7.5. The
reference flows for the sub-model are; weight of the mechanical enclosure (total 6117kg), weight of the
PBA (total 1239kg) and one PC unit for the NME (total 3 units).
Two back-up generators are provided to keep the cable powered during outages in the main electricity
network. These have been estimated from an LCA study into an AC generator with a functional unit of
1kW (ABB, 2009d). During the site visit to one terminal station, it was advised that two 650kW generators
were installed (McGrath, 2009). The reference flow for the sub-model is 1kW. The ABB study has been
scaled up to 1300kW and it is assumed this is comparable to the installed generators of the common
terminal station.
Construction materials for the terminal building have not been included in this study, see Section 4.4.4.4.
4.4.4. Design & Manufacturing Phase
The design & manufacturing sub-model accounts for the energy used in processing the raw materials into
the mechanical parts for the system. Similar to the raw materials sub-model, the manufacturing sub-model
is further divided into the three main components of a submarine cable system; the cable, submarine
repeaters and the terminal station. Surveying of the cable route (design) has been included under the cable
manufacturing process as the specific cable lengths must be defined prior to accurate manufacturing to
length. Energy recovery from incinerated waste is included in the sub-models. Database processes from
the GaBi software have been used to model the processing of wastes. The system includes energy use
(electrical) for the recycling of waste metals, which is then assumed to form a closed-loop recycling
process to reduce the initial virgin raw materials. This closed-loop recycling process is a simplification
based on input electrical energy and is further discussed in Section 4.4.7. Transportation of waste is
estimated at 100km as described in Section 4.4.2.2.
4.4.4.1. Cable Design (Route Surveying)
Prior to manufacturing, the cable route must be defined and surveyed by a research ship. The survey
determines the seabed topography, geology and any other obstacles or dangers to the cable. This in turn
affects the armouring selection for the cable and thus the manufactured lengths (Beaufils, 2000; Letellier,
2004). The average engine power rating for a research ship is estimated from two vessels working
specifically with cable route surveys (GMSL, 2009; confidential source). Fuel figures are taken from a
single survey where the author was present and averaged over 71 days of operations. It was not possible to
distinguish between transit and manoeuvring. A review of the emission factors shows that in most cases
manoeuvring emissions are slightly greater than at sea or transit emissions, thereby allowing for a worst
case scenario. The emission factors associated with the combustion of fuel onboard ships are further
defined in Section 4.4.2.1. Average research ship engine power and daily fuel consumption are presented
in Table 8 and Table 9.
Table 8: Engine Power: Average Research Ship (calculated from GMSL, 2009; confidential source).
Main Engine Power
(kW)
Auxiliary Engine Power
(kW)
Total Engine Power
(kW)
2311
650
3261
37
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
Table 9: Daily Fuel Consumption: Average Research Ship (calculated from confidential source).
In Port
(tonne)
Manoeuvring
(tonne)
1.02
5.03
The typical mission length to survey the cable route has been calculated from a survey (where the author
was present) of 4800km of cable route, lasting 71 days. The figures are normalised to 1,000km of cable.
The operations included both shallow water (<1,000m) and deepwater (>1,000m) surveys and are
assumed to be representative of the average cable survey. Typical mission lengths are presented in Table
10 below.
Table 10: Average Research Ship: typical survey mission normalised to 1,000km of cable (calculated from
confidential source).
Operation Mode
Route Survey
In Port
(days)
Manoeuvring
(days)
2.7
12.1
Based on the normalised survey mission, it is calculated that a total of 64 tonnes of fuel are used to survey
1,000km of cable.
Air travel to and from the ship has been estimated based on 35 personnel travelling an average of 2559km
per 1,000 kilometres of cable, giving a total of 89574pkm normalised to 1,000km of cable route survey.
Air travel is further described in Section 4.4.2.3.
The daily maintenance of the research ship has been calculated using the LCA study of Fet et al (1996)
described in Section 4.4.2.1. The surface area of the hull was estimated based on the length, breadth and
draft of the studied vessel in relation to the research vessel. A factor of 0.46 was calculated and applied to
the results of the study to account for the difference in ship size. The results of the study represent 10
years of total maintenance and were reduced to a daily figure. The paint itself is estimated from a process
for enamel paint, assumed to represent a similar process to the antifouling paint used for ships (Chalmers,
2009).
The reference flow for the sub-model is 1,000km of cable.
4.4.4.2. Cable Manufacturing
Data for cable manufacturing was collected from the Ericsson Network Technologies (formerly Ericsson
Cables) production plant. The manufacturing process has been simplified to the effect rating of the plastic
extrusion and armouring stations (Norlund, 2009). These are the two significant processes undertaken
during cable manufacture, though it is likely to underestimate the manufacturing energy demand as it does
not account for the plant operation as a whole. This simplification was made as the Hudiksvall plant
manufactures many other types of fibre optic cables. No allocation was attempted. It is assumed that all
input energy is in the form of electricity.
Waste from the production process is estimated at 1.5% (ibid) and is sent to scrap handlers for recycling
(Berggren, 2009). It is assumed that the cable is separated and that steel is the only recycled material, with
all other materials incinerated for energy recovery, providing between 0.8% to 1.6% return into the
system. A simplified closed-loop recycling process is included in the sub-model for the recycling of steel,
38
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
which is assumed to reduce the input of virgin raw materials. This closed-loop recycling process is further
discussed in Section 4.4.7.
Table 6 shows the ratio of the four primary cable types representing the generic system. The cable types of
four submarine systems, representing a total of over 40,000km of cable, were analysed and the results
normalised to 1,000km of cable. These values are applied to the manufacturing sub-model for each cable
type to give the resulting energy consumption and waste output for 1,000km of cable.
The reference flow for the sub-model is 1,000km of cable.
4.4.4.3. Submarine Repeater Manufacturing
No data could be sourced for the manufacture of submarine repeaters. Four manufacturers were
contacted, however, for confidentiality reasons, data could not be released. A repeater is made up of a
heavy outer metallic casing with internal electronics that boost the light signal. Due to the lack of data, the
assumption is made that the manufacture of a repeater is comparable by weight to that of the mechanical
enclosure and PBA sub-models assumed for the raw materials phase (3GLCA, 2002). This requires
approximately 50,000MJ of primary energy per repeater, where 75 percent of this energy is consumed for
the PBA process representing less than 2 percent of the weight. This assumption adds significant
uncertainty to this sub-model, as such a sensitivity analysis has been undertaken to determine the effect on
the results. Refer to Section 7.5.1 for the results of the sensitivity analysis.
The reference flow for the sub-model is 1 repeater unit. It is assumed that repeaters are placed every
50km, requiring 20 units per 1,000km of cable.
4.4.4.4. Terminal Equipment Manufacturing
Specific data for terminal station equipment could not be sourced in the given time limitation, therefore,
the manufacturing model is based on similar assumptions made for the raw materials and detailed in
Section 4.4.3.3. Data for the terminal raw materials have been defined by confidential terminal station
specifications and assumed from similar processes based on previous studies at Ericsson Research. Four
sub-models were created to account for the manufacturing of the raw materials into back-up batteries, the
power feed equipment (PFE), the submarine line terminal equipment (SLTE) and the back-up generators.
A fifth sub-model was created to account for the desktop study, which involves personnel visits to each
terminal site (Poole, 2009). A full list of data sources can be found in Appendix B. All electrical energy is
assumed to come from the average mix as described in Section 4.4.1.
A previous Ericsson cradle-to-gate study defined the electrical energy input and the waste outputs for the
manufacturing of a two volt (2V) cell, used in a radio base station (Pb-Battery, 2001). It is assumed that
wastes are treated in a hazardous waste process. Waste lead is recycled back into the raw materials subsystem in an assumed closed-loop process. The recycling process has been included as a simplified energy
input (electrical and heavy fuel oil energy) for the recycled lead based on the study by Salomone et al
(2005). No emissions from the recycling process are included. The reference flow for the sub-model is a
2V cell. Four battery banks are assumed, utilising 100 2V cells.
The PFE comprises direct current (DC) converters, monitoring equipment and mechanical enclosures
(cabinets). Manufacturing of the DC converters and monitoring equipment is defined in the ABB
documentation which includes electricity inputs and waste outputs (ABB 2009a; ABB, 2009b).
Manufacture for the cabinets has been taken from a previous Ericsson cradle-to-gate study for the
mechanical enclosure for a third generation (3G) mobile system (MECH, 2001). It is assumed that these
studies are representative of the common terminal station PFE. The PFE is described in more detail in
39
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
Section 4.4.3.3. It is assumed that all wastes are sent to landfill or treated if hazardous. These two
processes are defined by standard database models. No specific time horizon is given for emissions from
these processes, though it is assumed to be the 100 years surveyable period for landfill (Baumann and
Tillman, 2004). The reference flows for the PFE sub-model are; 1 kW equivalent per DC converter (total
20kW), one monitoring unit (total 4) and weight of mechanical enclosure (total 400kg).
The manufacture of the SLTE equipment is based on previous LCA studies for similar products. The
SLTE manufacture sub-model comprises the Ericsson 3G mechanical enclosure study (MECH, 2001),
manufacturing of printed board assembly (PBA) model (3GLCA, 2002; PBA, 2001) and the results from
an LCA of a personal computer (Williams and Sasaki, 2003) to model the network management
equipment (NME) manufacture.
The mechanical enclosure sub-model accounts for the energy consumption and waste output for the
manufacturing process. All incinerated wastes are assumed to generate recoverable energy, which provides
approximately 0.6% electrical energy and 4% thermal energy return into the system.
The PBA components have been assembled from previous work at Ericsson (3GLCA, 2002). The study
modelled the electrical components in a telecom node based on the construction of a standard board
model, with separate sub-models for the important manufacturing processes related to integrated circuits
(IC), printed circuit boards (PCB) and the PBA assembly process. IC manufacturing is important as it
consumes large amounts of electricity. PCB manufacturing has potential for very large and hazardous
emissions. A detailed description of these processes can be found in the Ericsson internal 3GLCA report
(2002) and the public report by Bergelin (2008). With these four sub-models it was assumed that PBAs in
all telecom nodes could be modelled (3GLCA, 2002). At the time of the study the component models
were considered complete, however, uncertainty is introduced as it is most likely that there has been
subsequent improvements in the manufacturing process (Bergelin, 2008).
Due to lack of data, the manufacturing process for the network management equipment (NME) is
simplified to the energy required to produce a single PC, estimated by Williams and Sasaki (2003) to be
5600MJ. It is assumed that this energy is secondary energy in the form of electricity modelled on the
average mix. No wastes or emissions are modelled for the NME, though it is assumed that their impact
would not significantly affect the result as the NME primary energy expenditure is 1% of the total
terminal primary energy use during manufacture. The PBA and NME sub-models have been scaled by a
factor of three in the terminal model to account for upgrading of the system. The reference flows for the
SLTE sub-model are; weight of the mechanical enclosure (total 6117kg), weight of the PBA (total 1239kg)
and one PC unit for the NME (total 3 units).
The manufacturing of the back-up generators is estimated from the ABB study into an AC generator
(ABB, 2009d). Energy consumption (electricity and thermal) and waste outputs are modelled for the
manufacturing process. All wastes are assumed to be treated as hazardous or sent to landfill, again with an
assumed 100 year time horizon. The reference flow for the sub-model is 1kW. Comparable to the raw
materials sub-model, the ABB study has been scaled up to 1300kW (2 x 650kW) and it is assumed this is
comparable to the installed generators of the common terminal station.
A desktop study (DTS) is undertaken prior to the manufacture of the cable in order to determine the
preliminary cable route and location of the terminal stations. The DTS generally includes one site visit per
cable landfall (Poole, 2009). The DTS is a simplified model based solely on air travel, which is assumed to
have the most significant impact. It is assumed that 3 persons travel a 20,000pkm round trip per site visit,
giving a total of 60,000pkm per terminal station. The air travel sub-model is further explained in Section
4.4.2.3. The reference flow for the DTS sub-model is 1 unit per terminal station.
40
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
The construction of the terminal building has not been included in this study. LCA studies relating to the
environmental impacts of buildings over their service life show that energy consumption during the use
phase is equal to, or in the case of more recent studies, significantly dominates the environmental impacts
of the building over the entire life-cycle (3GLCA, 2002; Guggemos and Horvath, 2005; Jönsson et al,
1998). Construction materials, energy and emissions can generally be excluded for capital equipment when
the impact of construction is minor in relation to the total impact of the use phase (USEPA, 2006). Two
cable terminal stations studied show a footprint size of approximately 270m2 and 220m2, with mixed
construction of concrete and steel framing. Given the energy demand of the cable and the terminal
equipment over its 13 year commercial lifetime, the impact from the construction of each terminal
building is assumed to be relatively small.
4.4.5. Installation Phase
4.4.5.1. Cable Installation
The installation phase of the cable involves a special purpose cable ship designed to store and lay the cable
from cable tanks within the ship’s hold. Due to the sheer weight and volume, 1,000km of lightweight
cable weighs approximately 500 tonnes, the cable must be transported by sea. In most cases the cable is
spooled onto the installation ship directly from the manufacturing plant. Review of confidential load and
lay reports show that loading achieves an average of approximately 90km per day. The installation rate of
the cable varies with the type of cable and the method of installation. The cable is generally ploughed into
the seabed out to 1,000 metres of water and surface laid thereafter. Lay reports show that on average a
distance of approximately 20km per day is achieved with ploughing and approximately 140km per day
with surface lay. These figures are assumed to represent the typical cable installation.
The average engine power rating for a cable ship is estimated from the average installed power rating of
seven vessels working specifically with cable installation and maintenance. Fuel figures are averaged over
the fleet based on the vessel specifications (GMSL, 2009). The emission factors associated with the
combustion of fuel onboard ships is further defined in Section 4.4.2.1. Average cable ship engine power
and daily fuel consumption are presented in Table 11 and Table 12.
Table 11: Engine Power: Average Cable Ship (calculated from GMSL, 2009).
Main Engine Power
(kW)
Auxiliary Engine Power
(kW)
Total Engine Power
(kW)
6896
2106
11537
Table 12: Daily Fuel Consumption: Average Cable Ship (calculated from GMSL, 2009).
In Port
(tonne)
Manoeuvring
(tonne)
At Sea
(tonne)
3.0
13.2
16.0
The typical mission lengths to load, clear the route and install the cable are calculated from confidential
installation reports. The figures are normalised to 1,000km of cable and are presented in Table 13 below.
The lay operations includes the combined average for both shallow water (<1,000m) and deepwater
(>1,000m) installation.
Table 13: Average Cable Ship: typical installation mission normalised to 1,000km of cable (calculated from
confidential source).
41
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
At Sea
(days)
Manoeuvring
(days)
In Port
(days)
8.08
0.07
11.66
PLGR
0.10
0.41
0.06
Lay
2.43
9.79
1.58
Total Days
10.6
10.3
13.3
Operation Mode
Load
8
Based on the normalised installation mission of approximately 34 days, it is calculated that a total of 345
tonnes of fuel are used to install 1,000km of cable.
Air travel for personnel is assumed to have a noticeable impact and has been modelled for the installation
phase. Travel to and from the vessel during “crew changes” is estimated based on 48 personnel made up
of officers and crew. Air travel has been calculated at an average of approximately 6600pkm per day’s
operation of the cable ship. Based on the calculate mission length of 34.18 days, the total air travel is
calculated at 224830pkm per 1,000km of cable installed. Air travel is further described in Section 4.4.2.3.
The daily maintenance of the cable ship has been included due to its release of pollutants into the marine
environment. This has been modelled using the LCA study of Fet et al (1996) described in Section 4.4.2.1.
The surface area of the hull was estimated based on the length, breadth and draft of the studied vessel in
relation to the cable ship. A factor of 1.87 was calculated and applied to the results of the study to account
for the difference in ship size. The results of the study represent 10 years of total maintenance and were
reduced to a daily figure. The paint itself is estimated from a process for enamel paint, assumed to
represent a similar process to the antifouling paint used for ships (Chalmers, 2009).
The reference flow for the installation sub-model is 1,000km of cable.
4.4.5.2. Repeater Installation
Repeaters are laid in conjunction with the cable installation and are inseparable from that process.
4.4.5.3. Terminal Installation
The construction of the terminal building is not included in this study - further explained in section
4.4.4.4.
4.4.6. Use & Maintenance Phase
The environmental impact from the use & maintenance phase results from the consumption of electricity
at the terminal and the maintenance of the cable with ships. Electricity at the terminal is consumed in
order to power both the cable repeaters and the terminal equipment. Power consumption figures from 2
terminal stations reveal that the cable consumes approximately 3.6% of the total energy budget for the
terminal station, when normalised to 1,000km of cable. This 3.6% has been allocated to the cable submodel with the remaining energy use allocated to the terminal sub-model. Electricity is modelled based on
the average mix, as detailed in Section 4.4.1.1. Maintenance of the cable is required when a fault develops
that requires repairing the cable with a purpose-built cable ship. The commercial lifetime of the cable at 13
years has been considered in this study (Ridder, 2007), however, the technical lifetime is considerably
8
Pre-Lay Grapnel Run (PLGR); used for route clearance prior to burying to cable by plough generally down to 1000
metres of water.
42
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
greater at 25 years (Beaufils, 2000). Sensitivity analysis has been undertaken to assess the environmental
impact based on the greater technical lifetime. The sensitivity analysis is detailed in Section 7.5.2.
4.4.6.1. Cable Use & Maintenance
Use & maintenance of the cable can be divided into the maintenance with ships and the electrically energy
required to power the repeaters. It is assumed that cable maintenance and repair is undertaken by a similar
ship as used for installation. Average engine and fuel consumption figures are presented in Table 11 and
Table 12. Emission factors are presented in Section 4.4.2.1.
The typical mission lengths to load, transit to the site and repair the cable have been calculated from the
operational record of four cable ships stationed on maintenance standby and covering a total of
197,000km of cable. Based on the number of repairs undertaken by these vessels during the period an
annual fault factor of 0.37 was calculated when normalised to 1,000km of cable (confidential source). This
figure is consistent with the work of Kordahi et al (2007). The number of vessel days on standby in port
was compared with the number of vessel days on repair operations. In order to estimate the emissions
from the combustion of fuel and due to lack of detailed data, it was necessary to make an assumption,
based on professional judgement, of the operation mode of the vessel during repair operations. Naturally,
this increases the uncertainty for this sub-model. Table 14 presents the estimated values.
Table 14: Average Cable Ship: Estimated operation mode per cable repair.
Operation Mode
Assumed
Transit
(At sea)
Operations
(Manoeuvring)
Loading
(In port)
50%
40%
10%
Based on the above assumptions, the annual repair mission normalised to 1,000km of cable was calculated
and is presented in Table 15.
Table 15: Average Cable Ship: Annual repair mission normalised to 1,000km of cable (confidential source).
Operation Mode
Total Days
At Sea
Manoeuvring
Port
2.1
1.7
3.6
Based on the 1,000km normalised repair mission, it is calculated that a total of 67 tonnes of fuel are used
annually.
As with other sub-models, air travel is assumed to have a noticeable impact. Travel to and from the vessel
during “crew changes” is estimated based on 48 personnel made up of officers and crew. Air travel has
been calculated at an average of approximately 6,600pkm per day’s operation of the cable ship. Based on
the annual operation time of 7.41 days, the total air travel is calculated at approximately 49,000pkm per
1,000km of cable maintained. Air travel is further described in Section 4.4.2.3.
The daily maintenance of the cable ship has been included and is explained further in Section 4.4.5.1.
Electricity is sent down the cable via the inbuilt copper conductor, in order to power the submarine
repeaters. Analysis of the DC power feed readings from two terminal stations is used to calculate the
average electricity requirement to power 1,000km of cable, being 1.09 kW at approximately one ampere
(1A). This equates to approximately 34 GJ of electricity annually and is roughly 3.6% of the total energy
43
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
budget for the terminal station. It is assumed that this figure represents the common cable system.
Electricity production is taken from the average mix sub-model, described further in 4.4.1.1.
The reference flow for the cable use & maintenance sub-model is 1 year of operation.
4.4.6.2. Terminal Use & Maintenance
The terminal electricity budget has been calculated from the monthly and yearly consumption of two
terminal stations (confidential sources). The total consumption of a typical terminal station including,
terminal equipment, climate control and lighting is calculated at approximately 191 kW, which equates to
roughly 6034 GJ of electricity annually. It is assumed that this figure represents the common cable system.
Electricity production is taken from the average mix sub-model, described further in 4.4.1.1.
Upgrading is likely to affect the energy use at the terminal due to efficiency gains in the equipment.
Consultation with persons working within the industry suggests that 3 upgrades are likely over the course
of the system’s 13 year commercial lifetime (Betts, 2009; Veverka, 2009). In order to avoid complexities in
the model, upgrading is simplified and is treated as a linear input during raw material production and
manufacturing. Upgrading and efficiency gains are not considered under the use & maintenance submodel.
The reference flow for the terminal use & maintenance sub-model is 1 year of operation.
4.4.7. End-of-Life Decommissioning Phase
A recovery and recycling scenario has been assumed for the end-of-life treatment of the cable based on
the main mechanical materials. Terminal station recycling has been considered for the lead acid batteries
and the PBA component only. It is assumed that this does not significantly affect the results. The scenario
for cable recovery and recycling is based on information provided by a company whose “core business is
the recovery and dismantling of redundant submarine cables” (Mertech, 2009, p1). Recently, this company
recovered 350km of the SAT-1 cable, decommissioned in 1993. While SAT-1 was not a fibre optic cable,
the same mechanical materials including, copper, steel and high-density polyethylene (HD-PE) plastic
were recovered and are therefore representative of modern fibre optic cables (Louw, 2009).
The reference flow for the recovery and recycling scenario sub-model is 1,000km of cable.
4.4.7.1. Cable Recovery
Recovery is similar to the installation process in that the cable must be recovered with a purpose-built
cable ship. Figures indicate that the recovery rate is similar to the installation rate (Louw, 2009). It is
therefore assumed that recovery of the cable is the exact reverse process to installation, resulting in the
same resource use and emissions. The installation sub-model described in Section 4.4.5.1 is used to
estimate the impact of recovery. Based on the installation sub-model, a total of approximately 34 days ship
operations and 345 tonnes of fuel are used to recover 1,000km of cable.
4.4.7.2. Cable Recycling
Cable recycling is a two part process involving dismantling of the cable into its separate mechanical
materials at the shipyard and then processing of the materials into recycled raw product. Cable dismantling
is undertaken using special purpose equipment drawing electrical power. Modelling of the dismantling
process has been simplified based on the total electricity consumption of the shipyard per unit length of
cable and is estimated at approximately 2.2 kWh per tonne (Louw, 2009). Copper, Steel and HD-PE are
separated and sent to recycling plants to be smelted into billets or palletised. Recovery of these materials is
44
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
considered to be 100 percent (Louw, 2009). However, allowing for loss during the recovery and recycling
process, it is assumed that 90 percent of the materials are available for return to the system to offset the
input of virgin materials in a closed-loop process. The 10 percent loss from the system is assumed to
result from the mechanical separation and smelting processes. This is likely to be a conservative estimate.
No emissions or wastes are modelled for this 10 percent loss.
Steel is one of the most recycled materials and is 100 percent recyclable without loss of quality or
properties. All ‘new’ steel products contain some recycled material (Corus, 2007; World Steel, 2008). Steel
production technologies use two methods; the basic oxygen furnace (BOF) utilising 25 to 35 percent scrap
steel and the electric arc furnace (EAF) utilising more than 80 percent scrap steel (Steel Recycling Institute,
2007). Most scrap steel is recycled using the EAF, with the main inputs being recycled steel and electricity
(BlueScope, 2009; World Steel, 2008). In this study it is assumed that all steel is recycled using the EAF.
The recycling process is simplified to the electricity consumption of the EAF, with no other emissions
accounted for. The literature shows primary energy consumption for recycling of steel ranges from 7 to
17.4 gigajoules per tonne (Jones, 2009; BlueScope, 2009; Corus, 2007; World Steel, 2008). Averaging these
figures and applying the primary to secondary energy factor, explained in Section 4.4.1.1, gives an average
electricity input of 796kWh per tonne of recycled steel – presented in Table 16.
Table 16: Energy consumption – steel recycling process (Jones, 2009; BlueScope, 2009; Corus, 2007; World
Steel, 2008).
Steel Recycling Energy
Corus Group
BlueScope Steel
World Steel Association.
American Iron and Steel institute
Primary
Secondary
(GJ/tonne)
(kWh/tonne)
(kWh/tonne)
17.4
4833
1267
7
1944
510
10.8
3000
787
-
-
620
Average Input Energy (Electricity)
796
Estimated Input Energy (Electricity)
800
For this study, 800kWh per tonne has been estimated for the recycling of steel. It is assumed that steel
recycled from the cable is of equal quality to virgin material, with a 10 percent loss in the recycling
process, thereby replacing 90 percent of the virgin material input. It is assumed that the zinc used for
galvanizing the steel wires is lost from the system. No emissions are modelled for this loss.
Worldwide, recycling rates of copper are between 40 to 60 percent, with demand far out weighing the
availability of scrap for recycling (Graedel et al, 2004; Lifset et al, 2002; Spatari et al, 2005). Losses in
production are only significant in milling and smelting. Refining and fabrication losses can be readily
recovered and returned to the system (Lifset et al, 2002). Giurco et al (2006) estimate that copper recycling
using a reverberatory smelter consumes 1200 kWh of electricity and 480kg of fuel oil with material
recovery of 88 percent. It is assumed that copper recycled from the cable is of equal quality to virgin
material, with a 10 percent loss in the recycling process, thereby replacing 90 percent of the virgin material
input.
High density polyethylene (HD-PE) recovered from the cable is processed into pellets for reuse. Louw
(2009) describes the material as “top-quality non-virgin material”. Dodbiba et al (2008) describe this
process as mechanically recycling, where the basic structure of the plastic material is unaffected. Mechanical
recycling of plastics is only effective if the recovered material is of high-quality (96% purity). Furthermore,
45
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
they compare energy recovery from incineration to mechanical recycling and conclude that the latter has
less environmental burden. Louw (2009) estimates the recycling of HD-PE to consume 400 kWh per
tonne of material. It is assumed that HD-PE recycled from the cable is of equal quality to virgin material,
with a 10 percent loss in the recycling process, thereby replacing 90 percent of the virgin material input.
Stainless steel has also been considered for recycling due to it containing scare and energy intensive
elements and the potential for emissions reductions when compared to virgin material (Igarashi et al,
2007). It is assumed that the recycling of stainless steel uses the same energy input as steel recycling at 800
kWh per tonne. Recovery is also assumed at 90 percent.
Tests show that the recovery of the fibre itself is economically unattractive as complete gel removal is not
possible. Energy recovery was therefore considered as potentially the best solution for the gel fractions
(Arnaiz et al, 2008). In this study no allowance has been made to recover energy from the gel as it accounts
for only 1 percent of the total weight of the lightweight cable.
The other main mechanical materials that make up the single armour (SA) and double armour (DA) cables
are polypropylene yarn and bitumen. These materials are sealed in drums and sent to a licensed landfill
(Louw, 2009). It is assumed that all non-recycled cable waste is treated in this way. The landfill process is
modelled based on the standard GaBi database process for commercial waste. No defined time horizon is
given for emissions, however, based on the literature (Baumann and Tillman, 2004), a cut-off at the
surveyable time period of approximately 100 years is assumed.
4.4.7.3. Repeater Recycling
It is assumed that the main mechanical materials of the repeater are recycled, particularly the 170kg
beryllium copper casing. Based on the assumptions made in Section 4.4.3.2, the repeater contains copper,
steel and stainless steel. Recycling of these materials is explained above in Section 4.4.7.2. In addition,
aluminium and the printed board assembly (PBA) are considered for recycling and waste handling.
Aluminium is in principle indefinitely recyclable as it retains its structure and inherent properties through
the melting process (EAA, 2007). Processing plants for secondary aluminium do not generally use
electrical energy for the furnaces, using mainly mineral oil and natural gas. However, the auxiliary
equipment does consume substantial quantities of electrical energy (Schmitz et al, 2006). Further, Schmitz
et al (2006) estimates the energy consumed by a reverberatory furnace to be between 1,000 to 1,200 kWh
per tonne. Green (2007) estimates the total energy consumed to produce secondary aluminium at
2,800kW per tonne. Accepting the upper limit of Schmitz et al (2006) at 1,200kWh per tonne and
assuming that this represents the fuel oil consumed, a total of 1,600kWh per tonne remains, as presented
in Table 17. It is assumed that this represents the electrical energy consumed during the recycling process.
Table 17: Energy consumption – aluminium recycling process (Green, 2007; Schmitz et al, 2006).
Aluminium Recycling Energy
Primary
(kWh/tonne)
Green, 2007 (Total)
2800
Schmitz et al, 2006 (Furnace only)
1200
Estimated Input Energy (Fuel Oil)
1200
Estimated Input Energy (Electricity)
1600
Electricity and heavy fuel oil come from the sub-models used throughout the study, explained further in
Sections 4.4.1.1 and 4.4.1.1. It is assumed that recycled aluminium is of equal quality to virgin material,
46
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
with a 10 percent loss in the recycling process, thereby replacing 90 percent of the virgin material input.
This is a conservative figure and no emissions are accounted for in relation to this loss.
It is assumed that the PBA is incinerated and the energy recovered, providing approximately 0.1 percent
return into the system. No material recovery has been considered. Emissions are accounted for by the
standard database process for PBA incineration.
4.4.7.4. Terminal Recycling
Recycling of the terminal components has been considered for the lead acid batteries and the PBA
elements only. These are considered to represent the most toxic substances in the sub-model. The lead
acid battery recycling has been based on a study by Salomone et al (2005). It is assumed that the PBA is
incinerated, which is modelled using database processes. Material recovery has not been considered. It is
further assumed that the remaining components of the terminal station, the mechanical enclosures and the
generators, are used for subsequent systems and therefore are lost from the system with no emissions or
waste generated.
4.5. Allocation
The ISO 14040 series guidelines state that where possible allocation should be avoided by increasing detail
in the model or expanding the system to include those processes requiring allocation. However, when
allocation cannot be avoided then, the environmental loads should be partitioned to reflect the underlying
physical relationship or other relationships, such as proportioned economic value (Baumann and Tillman,
2004; ISO 14044:2006).
Data for the raw materials and manufacturing processes for the cable has been provided by a number of
suppliers to Ericsson. These companies are likely to produce more than one product, hence the data must
be allocated (Bergelin, 2008). In this case, companies have undertaken the allocation of materials and
energy inputs, and any emissions, themselves. For confidentiality reasons, no control over this allocation
procedure was possible within the scope of this study. This leaves the data open to uncertainty as the
allocation method cannot be verified for the purposes of this study. The impact of this on the final result
is reduced significantly by the end-of-life scenario, which replaces 90 percent of the virgin material with
recycled material.
Allocation assumptions for the end-of-life phase are based on an approximation of a closed-loop recycling
process. The system accounts for the recycling of cable materials in a simplified model based on energy
consumption during the recycling process. This approximation is considered valid for materials, such as
metals, that retain their quality after recycling (Baumann and Tillman, 2004). It is assumed that the
recycled materials replace 90 percent of the virgin material input. Plastics are usually considered degraded
by the recycling process and may be allocated on a 50/50 method (ibid). For submarine cable recycling, no
loss of quality is observed (Louw, 2009) and it is assumed that recycled HD-PE also replaces 90 percent of
the virgin material. In line with the ISO 14040 series guidelines, a sensitivity analysis has been undertaken
on the end-of-life phase to determine the impact of this allocation assumption (ISO 14044:2006). The
sensitivity analysis is presented in Section 7.5.2.
47
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
4.6. Inventory Results and Discussion
4.6.1. Inventory Results
A summary of the significant LCI data is presented in Table 18. The values represent 99 percent of the
potential impact under each impact medium, thereby accounting for the most significant inputs and
outputs of the system. All LCI data is stored in a database containing the complete LCA model created
using the GaBi software.
Table 18: LCI result summary for submarine cable system
Commercial lifetime 13 years, 10,000km, 5.2 terminal stations
Substance
Impact Media
Amount
Unit
Hard coal
Resource
33537318
kg
Crude oil
Resource
21283296
kg
Natural gas
Resource
5419385
kg
Lignite
Resource
990209
kg
Uranium natural
Resource
1100
kg
Copper
Resource
800008
kg
Copper ore
Resource
5759909
kg
Gold
Resource
6.549
kg
Lead ore
Resource
309661
kg
Zinc ore
Resource
1242200
kg
Carbon dioxide
Air
270669959
kg
Carbon monoxide
Air
232314
kg
Halon (1301)
Air
0.0096
kg
Methane
Air
297449
kg
Nitrogen oxides
Air
4103853
kg
Nitrous oxides (NOx)
Air
293434
kg
NMVOC (unspecified)
Air
108425
kg
R 11 (trichlorofluoromethane)
Air
0.110
kg
R 114 (dichlorotetrafluoroethane)
Air
0.112
kg
R 12 (dichlorodifluoromethane)
Air
0.024
kg
Sulphur dioxide
Air
2658144
kg
Sulphur oxides (SOx)
Air
207900
kg
VOC (unspecified)
Air
28941
kg
Cobalt
Freshwater
102.0
kg
Copper
Freshwater
271.9
kg
Nickel
Freshwater
261.9
kg
Polycyclic aromatic hydrocarbons (PAH, unspec.)
Freshwater
168.9
kg
Selenium
Freshwater
258.5
kg
Vanadium
Freshwater
264.6
kg
Barium
Seawater
101.6
kg
Beryllium
Seawater
0.134
kg
Copper (+II)
Seawater
1471
kg
Tributyltinoxide
Seawater
1294
kg
Zinc (+II)
Seawater
910
kg
Chromium (unspecified)
Soil
1.243
kg
Arsenic (+V)
Soil
0.091
kg
Nickel (+II)
Soil
0.460
kg
48
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
4.6.2. LCI Discussion
This section presents a discussion on important aspects of the life cycle inventory (LCI).
4.6.2.1. LCI Data Quality
In comparing the five life cycle sub-models, data for the use & maintenance phase is considered the most
reliable. Notwithstanding that the data lacks transparency, as it is based on confidential information and
that the HFO model is biased toward EU and US production (explained further below), data in this phase
is based on measured data for terminal energy use and ship maintenance days. In addition, the electricity
model is defined by previous LCA studies and emissions from ships are modelled from the literature.
The least reliable data is for the raw materials and design & manufacturing phases, where large uncertainty
exists in the data due to data gaps, allocations made by suppliers and the use of material processes from
the GaBi database. Data collected from suppliers to Ericsson comes with high uncertainty as, in most
cases, this was presented in email form or as answers to the questionnaire, rather than official reports.
Therefore, it is difficult to verify the source and quality of this data. It is assumed that this data is based on
measured values, though again, the allocation methodology of this data is uncertain. Modelling of the
upstream processes has been taken from the standard databases. The quality of these processes is directly
affected by the quality of the source data (3GLCA, 2002).
4.6.2.2. Representativeness
The data collection process of this study is based on “voluntary information exchange” (3GLCA, 2002,
p.49). It is likely that environmental data is representative of the best available technologies based on
modern facilities with pro-active environmental profiles. Companies with poor or non-existent
environmental monitoring often do not release data or simply ignore requests to participate. The result is
that the available data may have “a tendency to reflect better-than-average conditions” (ibid). This is
illustrated by the sub-model for heavy fuel oil production, which is a 50:50 combination of EU and US
production. This does not take into account the production in other regions that may have less efficient
production methods or poorer environmental controls (ibid).
Emissions from the combustion of marine fuels have been based on residual oils (ROs), which, on a
global scale, the majority of ships use. However, the company used as the reference for cable ship
specifications advised that marine distillates (MDs) were used in their ships (Todd, 2009). As discussed
previously, MDs have significantly less emissions for NOx and SOx, which in turn will reduce the
potential impacts. Therefore, the use of RO emissions factors should be considered a worst-case scenario.
The difference in impact between RO and MD emissions is addressed in the sensitivity analysis in Section
7.5.2.
Data has been collected from many sources. Where only single source data was available it is assumed that
this is representative of the generic process. This raises the uncertainty of the result as verification is not
possible. Where similar data from multiple sources was available an average value has been calculated and
used in the model.
4.6.2.3. Completeness and Consistency
One of the objectives of this study has been to collect as up-to-date data as possible from suppliers and
operators. Given the complexity of the system and the time limitation of 20 weeks it was not possible to
collect detailed data on all aspects of the system, particularly submarine repeaters and components of the
terminal station. As such, published data from previous studies and databases of standard processes have
been used to fill the data gaps.
49
4. Life Cycle Inventory (LCI)
A life cycle assessment of fibre optic submarine cable systems
For the cable, data for the raw materials is near complete, with all significant processes accounted for
based on information from suppliers to Ericsson and standard databases within the GaBi software.
However, reliance on the published databases reduces consistency as it is not possible to verify the age,
uncertainties, system boundaries and allocation procedures for each standard process (3GLCA, 2002).
Manufacturing of the cable is based on the effect rating of the plastic extrusion and armouring stations.
This is likely to be an under estimation of the total energy requirement to manufacture the cable.
Emissions from the cable manufacturing process and the end-of-life recycling process are limited to the
emissions from electricity production. Therefore, these emissions are likely to be under estimated. Data
for the installation, use & maintenance and end-of-life phases for the cable is considered to be complete,
though comes with some uncertainty as the data is not verifiable within the scope of this study.
For the repeater and terminal station, it was not possible to source data for the raw material and
manufacturing phases within the study timeframe, as such, these processes have been represented by
similar processes from the literature. The effect of this on the results is explored in the sensitivity analysis
in Section 7.5.1. The consequence of this data gap and the results of the sensitivity analysis must be taken
into account when considering the final result. The installation phase for the terminal station has been
assumed to have little effect on the result and has not been modelled. Data for the use & maintenance
phase for the terminal station has been taken from measured values at a number of terminal stations,
which agree with good consistency. Data for the end-of-life phase is again affected by the data gap
described above and subsequent assumptions.
For consistency, the average electricity mix and heavy fuel oil (HFO) sub-models have been used for all
respective electricity and HFO inputs throughout the model.
50
5. Life Cycle Impact Assessment (LCIA)
A life cycle assessment of fibre optic submarine cable systems
5. Life Cycle Impact Assessment (LCIA)
This section describes the life cycle impact assessment (LCIA), which “aims at describing the environmental
consequences of the environmental loads quantified in the inventory analysis” (Baumann and Tillman, 2004,
p.129). Impact categories, category indicators and the characterisation models are based on the CML
problem-oriented approach that focuses on environmental problems or the so-called midpoint of the causeeffect chain (Guinée et al, 2004).
5.1. General Allocation Procedure
Classification of the LCI data can result in parameters being assigned to more than one impact category.
For example, emission of nitrogen oxides (NOx) can be assigned to the acidification, eutrophication and,
in some cases, the photo-oxidant formation categories. Multiple assignments should only be made if the
effects are independent of each other, otherwise double-counting arises (Baumann and Tillman, 2004).
The case of NOx can be considered a serial mechanism, whereas, in the case of parallel mechanisms, such
as sulphur dioxide (SOx), the parameter should be apportioned between impact categories, such as, human
health and acidification (ISO 14044:2006). Previous studies show that the impact of SOx on human health
is negligible in comparison to the contribution to acidification. Leading to a general conclusion “…that
other uncertainties probably will overshadow the need for partitioning or allocation” (3GLCA, 2002,
p.53). Thus, in this study, the problem of allocation between impact categories has not been addressed.
5.2. Definition of Impact Categories and Characterisation Factors
The characterisation models used in this study follow the method developed by the Institute of
Environmental Sciences (CML) at the University of Leiden, in the Netherlands. This CML methodology
uses a problem-oriented approach that focuses on environmental problems or the so-called midpoint of the
cause-effect chain (Guinée et al, 2004). Impact categories, category indicators and the characterisation
models, along with the methodology and scientific rationale for the CML impact assessment models are
described in detail in Guinée et al, (2004). In this study, ten baseline impact categories (group A categories)
have been selected using the CML 2001 characterisation database supplied with the GaBi software. Each
impact category is described in the following sections and summarised below in Table 19.
Table 19: CML impact categories used for the life cycle impact analysis (Adapted from Guinée et al, 2004).
9
Impact Category
Year
Indicator
Abiotic Resource Depletion
2001
kg Sb eq. 9
Acidification Potential
2001
kg SO2 eq.
Freshwater Ecotoxicity Potential
2001
kg 1,4DCB eq.
Terrestrial Ecotoxicity Potential
2001
kg 1,4DCB eq.
Marine Aquatic Ecotoxicity Potential
2001
kg 1,4DCB eq.
Global Warming Potential
2001
kg CO2 eq.
Photochemical Ozone Creation Potential
2001
kg C2H4 eq.
Ozone Depletion Potential
2001
kg CFC-11 eq.
Eutrophication Potential
2001
kg PO4 eq.
Human Toxicity Potential
2001
kg 1,4DCB eq.
eq. - abbreviation for ‘equivalent’.
51
5. Life Cycle Impact Assessment (LCIA)
A life cycle assessment of fibre optic submarine cable systems
5.2.1. Abiotic Resource Depletion
Depletion of abiotic resources relates to the irreversible use of natural non-living resources such as metals,
minerals and fossil fuels. The abiotic depletion potential (ADP) for each resource is determined from the
extraction rate and the remaining reserves. These are then compared to the reference case for depletion of
the rare metal antimony (Sb). The reference unit is kilograms Sb equivalent (kg Sb eq.) (BRE, 2005;
Guinée et al, 2004).
5.2.2. Acidification Potential
Acidification results from acidifying pollutants reacting with water in the atmosphere to form “acid rain”.
This has a detrimental effect on biological organisms, ecosystems and materials, such as buildings. The
characterisation model is adapted to LCA based on the RAINS10 model describing the deposition of
acidifying substances. The major pollutants are sulphur dioxide (SO2), nitrogen oxides (NOX) and
ammonia (NH3). The acidification potential (AP) of each pollutant is expressed in the reference unit of
kilogram emissions of SO2 equivalents (kg SO2 eq.) (BRE, 2005; Guinée et al, 2004).
5.2.3. Ecotoxicity Potential to Freshwater, Land and Seawater
Ecotoxicity relates to emissions of toxic substances having a detrimental effect on ecosystems. The
characterisation model is adapted to LCA based on the USES 2.0 model which describes fate, exposure
and effects of toxic substances. Freshwater aquatic ecotoxicity potential (FAETP) relates to the impact on
freshwater aquatic ecosystems, marine aquatic ecotoxicity potential (MAETP) relates to marine aquatic
ecosystems and terrestrial ecotoxicity potential (TETP) relates to land-based ecosystems. Emissions are
related to the reference unit of kilograms of 1,4-dichlorobenzene equivalents (kg 1,4DCB eq.) (BRE, 2005;
Guinée et al, 2004).
5.2.4. Global Warming Potential
Global warming potential or “climate change” relates to the impact of human emissions of greenhouse
gases (GHGs) and the resultant radiative forcing of the atmosphere. The characterisation model has been
developed by the Intergovernmental Panel on Climate Change (IPCC) describing the global warming
potential for a 100-year time horizon (GWP100). Emission factors are measured against the reference unit
of kilograms of carbon dioxide equivalents (kg CO2 eq.) (BRE, 2005; Guinée et al, 2004).
5.2.5. Photochemical Ozone Creation Potential
Photochemical ozone creation is the effect of emissions such as carbon monoxide (CO) and volatile
organic compounds (VOCs) that cause ozone to be created in the presence of sunlight, commonly seen as
summer smog. Winter smog, by contrast, is considered under human toxicity. Photochemical ozone
creation potential (POCP) relates to the detrimental effects on human health and is modelled by the
UNECE Trajectory model. Emission factors are measured against the reference unit of kilograms of
ethylene equivalents (kg C2H4 eq.) (BRE, 2005; Guinée et al, 2004).
5.2.6. Ozone Depletion Potential
Stratospheric ozone depletion refers to the breakdown of ozone in the stratosphere resulting in a thinning
of the ozone layer. This is caused by the anthropogenic emission of ozone-depleting gases to air. The
ozone depletion potential (ODP) of different gases is modelled by the World Meteorological Organisation
(WMO) and relates to human health and ecosystem effects caused by ozone depletion. Emissions of gases
are measured against the reference unit of kilograms of chloroflurocarbon-11 equivalents (kg CFC-11 eq.)
(BRE, 2005; Guinée et al, 2004).
52
5. Life Cycle Impact Assessment (LCIA)
A life cycle assessment of fibre optic submarine cable systems
5.2.7. Eutrophication Potential
Eutrophication relates to the concentration of high levels of macronutrients in the environment. Nitrates
and phosphates are essential for life, however increased levels can lead to detrimental shifts in species
composition and elevated biomass concentrations, such as excessive algae growth in aquatic ecosystems.
The eutrophication potential (EP) of emissions are modelled by the stoichiometric procedure and are
measured against the reference unit of kilograms of phosphate equivalents (kg PO4 eq) (BRE, 2005;
Guinée et al, 2004).
5.2.8. Human Toxicity Potential
Human toxicity relates to emissions of toxic substances having a detrimental effect on human health. The
characterisation model is adapted to LCA based on the USES 2.0 model which describes fate, exposure
and effects of toxic substances. The human toxicity potential (HTP) of each toxic substance emitted to air,
water and soil is measured against the reference unit of kilograms of 1,4-dichlorobenzene equivalents (kg
1,4DCB eq.) (BRE, 2005; Guinée et al, 2004).
5.3. Classification and Characterisation Summary
Classification involves the qualitative process of assigning the inventory data to each of the impact
categories. In this case, no classification is needed as this process is defined by the CML methodology and
factors are assigned in the characterisation database (Guinée et al, 2004).
Characterisation is the quantitative process of calculating the indicator results for each impact category
based on the conversion of the LCI data to common units and the aggregation of the results (ISO
14040:2006). The result is a category indicator for each impact category, which together represent the
environmental profile of the studied system (Guinée et al, 2004). Again, characterisation factors are
defined in the CML 2001 characterisation database.
5.4. Definition of Normalisation Factors
The aim of normalisation is to relate the characterisation results to a background or reference value that
reflects the actual magnitude of the impact. This identifies if the impact is significant in relation to the
total impacts of the studied area, which may have global or regional consequences (Baumann and Tillman,
2004). Normalisation factors used in this study are taken from Sleeswijk et al (2008), where the annual
world reference values for the emissions and consumption of the significant substances under each impact
category are collate for the year 2000. This then helps to frame the environmental profile of a submarine
cable system within the greater economic system that it is a part of (Sleeswijk et al, 2008).
The resource and emission data presented by Sleeswijk et al (2008) have been divided by the world
population for the year 2000, estimated at 6.12 billion (UN, 2009), resulting in an environmental impact
expressed as annual person equivalents.
In attempting to quantify the global environmental impact, normalisation itself may result in uncertainties
due to doubt in the emissions data and in the characterisation factors (Sleeswijk et al 2008). As such,
qualitative assessment of the uncertainty has been undertaken by the authors. They note that the highest
level of uncertainty is associated with the toxicity categories due to the scarcity of data and the uncertain
fate modelling of heavy metals. While the lowest uncertainty from a global perspective is associated with
global warming, acidification and photochemical ozone creation. To avoid introducing greater uncertainty
into the results, only these three categories will be analysed for the purposes of normalisation. The
normalisation factors are presented in Table 20.
53
5. Life Cycle Impact Assessment (LCIA)
A life cycle assessment of fibre optic submarine cable systems
Table 20: World normalisation factors, person equivalents per year (Adapted from Sleeswijk et al, 2008).
Unit
Normalization Factor
(per capita per year)
Acidification (500 years)
kg SO2 eq.
61.8
Global Warming (100 years)
kg CO2 eq.
6830
kg NMVOC eq.
57.4
Impact Category
Photochemical Ozone Creation
These normalisation factors are compared to the results based on the functional unit and the estimated
per capita data annual traffic, to provide a percentage value relating to the annual environmental impact of
one person per year. The results of the normalisation calculation are presented in Section 7.6.
54
6. Calculation Procedure
A life cycle assessment of fibre optic submarine cable systems
6. Calculation Procedure
This section describes the calculation procedure for taking the results of the LCIA and presenting them in
relation to the functional unit of the study.
In order to generate the LCIA results for each impact category, the LCI data must be multiplied with the
corresponding characterisation factor. The characterisation factors used in this study are taken from the
CML database - year 2001.
The modular system of the GaBi software allows for the model to be analysed as a whole or by submodel, down to individual processes. The model for the generic cable system is built up of two main submodels, the cable and the terminal station. These two sub-models allow for the flexibility in analysing the
system, whereby scaling of the cable length and the number of terminals can, in principle, allow modelling
of any particular repeated submarine cable network.
Cable systems are decidedly variable in architecture and can be built as point-to-point, branched or ringed
systems, as shown in Section 2.2.3. Consequently, the length of cable and number of terminal stations can
vary considerably. In order to estimate the architecture of the generic system, a total of 24 networks were
averaged from three key regions; Transatlantic, Transpacific and South Asia (Europe to the Far East). A
summary of each region is presented in Table 23, with full details presented in Appendix A.
Table 21: Calculation summary for the generic cable system (Adapted from Ruddy, 2006).
Cable Region
Number of
Systems
Total Length
(km)
Lit Capacity
(Gbps)
Design
Capacity, est.
(Gbps)
Lit Capacity
as % of
Design
Total
Landings
Transatlantic
11
128201
2707
12217
22.16%
49
Transpacific
5
111536
1320
9060
14.57%
30
South Asia
8
149213
829
15636
5.30%
125
Total
24
388950
4856
36913
13.16%
204
Average generic system
1
16206
202
1538
13.16%
8.5
Normalised to 10000km of cable
10000
5.2
The results of the LCIA for the 13 year life cycle of the cable are based on a system normalised to 10,000
kilometres of cable, in order to relate to the functional unit. This then allows for the calculation of the
potential impacts to send 1 gigabit (Gb) of data over 10,000km of cable. However, in order to complete
the functional unit calculation, an additional calculation is necessary based on system capacity and actual
data traffic (or bandwidth usage). System capacity is defined by three figures; design capacity: the technical
limits to system capacity, lit capacity: the current installed capacity at the terminal station and, bandwidth
usage: the actual usage of the system (Telegeography, 2009). Table 21 shows that on average only 13
percent of the design capacity is currently lit. The fact that over 85 percent of the capacity remains unlit
highlights the significant potential for system upgrading, without the need to build new systems (Kidorf,
2006). Telegeography (2009) note that used capacity should not be interpreted as actual data traffic,
however, in this study it is assumed that used capacity approximates data traffic.
55
6. Calculation Procedure
A life cycle assessment of fibre optic submarine cable systems
The capacity calculation is based on an assumption of the modern system, whereby the average capacity is
calculated from systems installed on, or after, the year 2000 and with a capacity greater than 100Gbps. A
total of 11 systems fulfil this criterion, as detailed in Appendix A. If all 24 systems are used in the
calculation, then the lit capacity is averaged at approximately 200Gbps (see Table 21). However, this data
is then biased by the older systems, in the worst case having only 1 or 2Gbps total capacity. Therefore, the
older systems have not been used in this calculation in order to provide a reasonable estimate of cable
capacity based on current technology. Using the average capacity of the 11 systems, it is estimated that the
current lit capacity of the modern cable system is 400Gbps. However, research by Telegeography (2009)
shows that actual used bandwidth is, on average, only 25 percent of the lit capacity. Assuming bandwidth
usage approximates data traffic then the average data traffic is calculated at 100Gbps. This figure should
be considered an average for the generic system and individual systems may vary.
If this 100Gbps is multiplied by the number of seconds in a year and then by the 13 year lifetime of the
system, the annual and lifetime data traffic is estimated. A summary of this calculation is presented below
in Table 22.
Table 22: Summary of capacity calculation for the generic cable system (Adapted from Ruddy, 2006).
Capacity Calculation
Average lit capacity of modern system (>year2000 and >100Gbps)
381
Gbps
Estimated current lit capacity of modern system
400
Gbps
Assumed bandwidth usage of modern system at 25%
100
Gbps
Estimated total annual data traffic of modern system
3155692600
Estimated total lifetime data traffic of modern system
41024003800
Gb/year
Gb/lifetime
This gap between used capacity and lit capacity reflects the structure of the cable market influenced by a
number of factors; reserved restoration capacity and allocation for future needs by bandwidth purchasers,
market inefficiencies, contract structures and reserved spare inventory by the bandwidth suppliers
(Telegeography, 2009).
The results of the LCIA are based on a 13 year system lifetime and normalised to 10,000km of cable and
5.2 terminal stations (Table 21). These results are then divided by the estimated lifetime data traffic (Table
22) to give the resultant potential impact of 1Gb of data sent over 10,000km of cable, thereby relating to
the functional unit of 10,000Gb·km. The results and life cycle interpretation are presented in Section 7.
It must be acknowledged that this calculation assumes a steady state and does not allow for capacity
upgrading. However, upgrading will work to reduce any future potential environmental impacts. The
results must therefore be viewed in the context of this data traffic calculation. Furthermore, this
calculation is linear, and for future application, the results of this study can be scaled by a factor relating to
the estimated annual data traffic of this study and actual annual traffic of the system under investigation.
Though care must be taken to account for the difference between one data bit and one byte of data.
56
7. Results of Life Cycle Interpretation
A life cycle assessment of fibre optic submarine cable systems
7. Results of Life Cycle Interpretation
This section details the results of the life cycle interpretation, which are presented in relation to the
functional unit using a variety of bar charts in the following sections.
Firstly, the results based on the functional unit are summarised for each impact and energy category.
Secondly, each impact/energy category is analysed individually based on the life cycle phases. Thirdly,
each life cycle phase is analysed based on the components of the system; cable, repeaters and terminal
station. This section gives particular attention to the climate change potential, as this is of particular
interest to Ericsson in their research into the total carbon footprint of the global ICT network.
The results are based on what is considered to be world average values and no attempt has been made to
model regional differences. It is not possible to extract the electricity or fuel oil consumption from the
primary energy value for each GaBi database process, therefore, electricity and fuel oil consumption will
be under estimated for the raw materials phase. All other phases are near complete.
It is important to remember when interpreting the results, that an LCA is based on models and that these
models are simplifications of reality (3GLCA, 2002).
57
7. Results of Life Cycle Interpretation
A life cycle assessment off fibre optic submarine cable systems
7.1. Summary of Results
esults
Commerical lifetime 13 years, 10000km and 5.2 terminal stations
Primary Energy
Electricity
Heavy Fuel Oil
Abiotic Resource Depletion
Acidification Potential
Freshwater Aquatic Ecotoxicity Potential
Terrestric Ecotoxicity Potential
Marine Aquatic Ecotoxicity Potential
Global Warming Potential
Photochemical Ozone Creation Potential
Ozone Depletion Potential
Eutrophication Potential
Human Toxicity Potential
0%
Raw Materials
10%
20%
30%
Manufacture
40%
Installation
50%
60%
70%
Use & Maintenance
80%
90%
100%
End of Life
Figure 18: Summary of results – per 10,000Gb·km.
The results are presented in Figure 18 and show that the use & maintenance phase clearly dominates all
impact categories at an average of 66 percent,
percent with the exception of the ozone depletion potential (ODP)
category. By comparison, the raw materials and design & manufacturing phases account for, on average,
only 6 percent of the total potential impact. Again, this is with the exception of ODP, which represent 67
percent of the impact. The result is not unexpected as large
large amounts of electricity and fuel oil are
consumed during the 13 year use & maintenance of the cable. By comparison, it has been noted that the
planning, design, manufacture and installation phases take approximately 18 months. The end-of-life
end
phase includes recycling of the recovered materials,
materials which offsets 90 percent of the virgin material input in
an assumed closed-loop cycle, thereby reducing the impact of the raw materials phase significantly. Ozone
depletion is significantly higher for the raw materials
mate
phase due to the release of halogenated organic emissions
during material processing.
58
7. Results of Life Cycle Interpretation
A life cycle assessment of fibre optic submarine cable systems
Table 23: Summary of results – per 10,000Gb·km.
Impact Category
Units
Total
10000Gb·km
Raw
Materials
Design &
Manufacture
Installation
Use &
Maintenance
End of Life
Primary Energy
MJ
6.580E-02
4.620E-03
2.254E-03
3.892E-03
4.818E-02
6.849E-03
kWh
3.090E-03
2.206E-05
9.817E-05
2.390E-09
2.792E-03
1.777E-04
kg
4.041E-04
0.000E+00
1.549E-05
8.415E-05
2.124E-04
9.205E-05
Abiotic Resource
Depletion
kg Sb eq.
2.390E-05
1.623E-06
8.228E-07
1.861E-06
1.677E-05
2.819E-06
Acidification
Potential
kg SO2 eq.
1.402E-04
7.103E-07
5.103E-06
2.763E-05
7.852E-05
2.823E-05
Freshwater Aquatic
Ecotoxicity Potential
kg 1,4DCB eq.
1.591E-04
2.323E-06
5.341E-06
6.619E-06
1.309E-04
1.395E-05
Terrestrial Ecotoxicity
Potential
kg 1,4DCB eq.
1.948E-05
1.642E-07
7.495E-07
2.757E-06
1.264E-05
3.172E-06
Marine Aquatic
Ecotoxicity Potential
kg 1,4DCB eq.
5.914E-01
2.029E-02.
1.905E-02
5.603E-02
4.218E-01
7.428E-02
Global Warming
Potential
kg CO2 eq.
6.852E-03
1.790E-04
2.676E-04
9.225E-04
4.409E-03
1.075E-03
Photochemical Ozone
Creation Potential
kg C2H4 eq.
7.423E-06
7.399E-08
2.954E-07
1.452E-06
4.111E-06
1.491E-06
kg CFC11 eq.
8.308E-12
4.227E-12
1.358E-12
5.841E-13
1.484E-12
6.547E-13
Eutrophication
Potential
kg PO4 eq.
1.417E-05
9.456E-08
4.961E-07
2.796E-06
7.900E-06
2.879E-06
Human Toxicity
Potential
kg 1,4DCB eq.
2.811E-03
1.881E-05
1.051E-04
4.813E-04
1.694E-03
5.122E-04
Electricity
Heavy Fuel Oil
Ozone Depletion
Potential
The results for each impact category, based on the functional unit, are presented in Table 23. The results
show that over the 13 year commercial lifetime of the system, an equivalent of 3Wh of electricity and 0.4
grams of fuel oil are consumed per 10,000Gb·km. Impacts of interest are Climate Change and
Acidification. The results reveal that 6.9 grams of carbon dioxide equivalents (CO2 eq.) and 0.14 grams of
sulphur dioxide equivalents (SO2 eq.) are released per 10,000Gb·km.
59
7. Results of Life Cycle Interpretation
A life cycle assessment of fibre optic submarine cable systems
7.2. Application of Results
In order to place the results of the previous section into context, a number of examples are presented in
this section based on the global warming potential category.
Referring back to the telepresence example presented in Section 3.2.2, a telepresence conference between
Stockholm and New York would equate to the functional unit at 1.25Gb of data sent over 8,000km of
cable. If this conference lasted 60 minutes then a total of 518,400Gb·km would result, giving a functional
unit factor of 51.8. Applying this factor to the global warming potential impact result of 7 grams of carbon
dioxide (CO2) equivalents, then a total of 355 grams of CO2 equivalents would potentially be released for
the data transfer by submarine cable, per 60 minute telepresence conference. Studies show that 120 grams
of CO2 is released per person kilometre of air travel (see Section 4.4.2.3) and 160 grams of CO2 are
released per kilometre for the average new EU-15 passenger car in 2006 (3GLCA, 2002; European
Commission, 2007). If the above example is then compared to the alternative of a face-to-face meeting
requiring air travel, then 355 grams of CO2 would potentially be released by a single person flying only 3
kilometres. If compared to the average passenger car, then this would equate to 2.2 kilometres. Table 24
shows a summary of this calculation.
Table 24: Comparison of results – Climate change: Example 1 (Adapted from 3GLCA, 2002; European
Commission, 2007; Jonsson, 2009b).
Data transfer via subsea cable
Telepresence System
Air Travel
Car Travel
Impact
355 grams CO2 eq.
355 grams CO2
355 grams CO2
Utility
60 minutes use of system
3 km
2.2 km
Comparison Factor
Assumptions: Telepresence bandwidth = 18Mbps transferred over 8,000km of cable. Note: Submarine cable data transfer only.
Further expansion of this example can assume a two day meeting with a total of 16 hours of telepresence
use. Data transfer via the submarine cable would potentially release a total of 5.7 kilograms of CO2
equivalents in 16 hours. By comparison, the air travel for a single person roundtrip would amount to
16,000 kilometres, resulting in 1920 kilograms of CO2 emissions. The comparison is shown in Table 25.
Table 25: Comparison of results – Climate change: Example 2 - Single person, 2 day meeting. (Adapted from
3GLCA, 2002; Jonsson, 2009b).
Data transfer via subsea cable
Telepresence System
Air Travel
Impact
5.7 kg CO2 eq.
1920 kg CO2
Utility
16 hours use of system
16,000 km
Comparison Factor
Assumptions: Telepresence bandwidth = 18Mbps transferred over 8,000km of cable.
Note: Submarine cable data transfer only.
These examples clearly show the environmental benefits of using the ICT network, however, it must
noted that they compare only data transfer by submarine cable to air travel. In reality the telepresence
system is more complex and has a greater environmental impact as a whole (Jonsson, 2009b) as does
international travel for a face-to-face meeting. It is not considered that air travel will be replaced entirely
by submarine cable data transfer.
60
7. Results of Life Cycle Interpretation
A life cycle assessment of fibre optic submarine cable systems
7.3. Results by Environmental Impact Category
The following section presents the results by individual impact category and in relation to the functional
unit of 10,000Gb·km. Overall, the results clearly highlight the dominance of the use & maintenance phase
and the significant impact that electricity production and the combustion of heavy fuel oil (HFO) have on
the outcome.
7.3.1. Energy Resources
Electricity (kWh)
0
0,0005
0,001
0,0015
0,002
0,0025
0,003
End of Life
Use &
Maintenance
Installation
Manufacture
Raw Materials
0
0,01
0,02
0,03
0,04
0,05
Energy (MJ)
Primary Energy
Electricity
Figure 19: Primary Energy vs. Electricity consumption - per 10,000Gb·km.
Electricity consumption by the terminal station during the use & maintenance phase dominates at 90
percent, as shown in Figure 19. The link between electricity consumption and total primary energy
consumption is also apparent, representing over 99 percent of the primary energy count for the use &
maintenance phase. Very little electricity is accounted for during the raw materials phase as it is not
possible to extract the electricity consumption from the primary energy value for each GaBi database
process. However, the total primary energy use for raw materials represents only 7 percent of the total
energy use for the system. Electricity used during the end-of-life phase represents the material recycling
process.
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A life cycle assessment of fibre optic submarine cable systems
HFO (kg)
0
0,0002
0,0004
0,0006
0,0008
0,001
0,0012
End of Life
Use & Maintenance
Installation
Manufacture
Raw Materials
0
0,01
0,02
0,03
0,04
0,05
Energy (MJ)
Primary Energy
Heavy Fuel Oil
Figure 20: Primary Energy vs. Heavy Fuel Oil consumption – per 10,000Gb·km.
Figure 20 shows that heavy fuel oil (HFO) consumption by ships during the maintenance of the cable
presents the largest impact at 53 percent. The link between HFO consumption and total primary energy
consumption for the installation phase is apparent. The use & maintenance phase shows that the primary
energy count for HFO is much less in relation to electricity. HFO is consumed by the maintenance of the
cable with no HFO used by the terminal. No HFO is accounted for during the raw materials phase as it is
not possible to extract this from the primary energy value for each GaBi database process. However,
again, the total primary energy use for raw materials represents only 7 percent of the total energy use for
the system. The relatively high values for HFO for the installation and end-of-life phases at 21 and 23
percent respectively, result from HFO consumption by the cable ship operations in laying and recovering
the cable.
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A life cycle assessment of fibre optic submarine cable systems
7.3.2. Resource Depletion
End of Life
Use & Maintenance
Installation
Manufacture
Raw Materials
0
0,000005
0,00001
0,000015
0,00002
ADP (kg Sb eq.)
Figure 21: Abiotic resource depletion potential - per 10,000Gb·km.
Figure 21 shows that the use & maintenance phase clearly dominates resource depletion at 70 percent.
The principal resources for this indicator are crude oil used to produce heavy fuel oil (HFO) for cable
maintenance and hard coal (with natural gas impacting to a lesser extent) used to produce electricity
consumed at the terminal station. Electricity has the greatest effect on the use & maintenance phase at 71
percent. The end-of-life phase makes a positive contribution due to the recovery and recycling process
which consumes both HFO and electricity. Recycling of the materials is assumed to replace 90 percent of
the virgin material input, hence the relatively small impact resulting from the raw materials phase.
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A life cycle assessment of fibre optic submarine cable systems
7.3.3. Acidification
End of Life
Use & Maintenance
Installation
Manufacture
Raw Materials
0
0,00002
0,00004
0,00006
0,00008
0,0001
AP (kg SO2 eq.)
Figure 22: Acidification potential - per 10,000Gb·km.
The two important indicators for Acidification are sulphur dioxide (SO2) and nitrogen oxides (NOx).
Again, the production of electricity and the combustion of heavy fuel oil (HFO) during the use &
maintenance phase represent the greatest impact at 56 percent, as presented in Figure 22. HFO
combustion during cable maintenance dominates the impact by a factor of 10, over the production of
electricity used at the terminal, confirming the high acidification impact of shipping, as presented in the
literature. China represents the greatest acidification impact for electricity production by a factor of 12 in
relation to US production and 25 to Japan, indicating the high use of coal in China. The relatively high
values for the installation and end-of-life phases at 20 percent, are linked directly to the HFO
consumption by the cable ship operations, presented in Figure 20.
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A life cycle assessment of fibre optic submarine cable systems
7.3.4. Ecosystem Toxicity
MAETP (kg 1,4DCB eq.)
0
0,1
0,2
0,3
0,4
0,5
-6,78E-19
0,00003
6E-05
9E-05
0,00012
0,00015
End of Life
Use & Maintenance
Installation
Manufacture
Raw Materials
TETP & FAETP (kg 1,4DCB eq.)
Terrestric Ecotoxicity Potential
Freshwater Aquatic Ecotoxicity Potential
Marine Aquatic Ecotoxicity Potential
Figure 23: Ecotoxicity potential - per 10,000Gb·km.
Emissions of heavy metals to water and air represent the major contribution to Ecosystem Toxicity. As
shown in Figure 23, the significant use of heavy fuel oil (HFO) and electricity during the use &
maintenance phase results in the greatest impact at an average of 73 percent. Selenium and vanadium are
the significant contributors from the production of electricity, representing on average 65 percent of the
emissions from the use & maintenance phase in relation to terminal energy use. Vanadium and Barium are
the major contributors from the production of HFO, while combustion of HFO releases nickel in the
greatest amount. Copper, zinc and the pesticide tributyltinoxide are the principal contributors from the
maintenance of the ship’s hull. These factors together combine to represent an average of 35 percent of
the use & maintenance impact associated with cable maintenance by ship.
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A life cycle assessment of fibre optic submarine cable systems
7.3.5. Climate Change
End of Life
Use & Maintenance
Installation
Manufacture
Raw Materials
0
0,001
0,002
0,003
0,004
0,005
GWP100 (kg CO2 eq.)
Figure 24: Climate change potential - per 10,000Gb·km.
As shown in Figure 24, actual carbon dioxide (CO2) emissions to air, from the production of electricity,
used at the terminal and the combustion of heavy fuel oil (HFO), consumed by cable maintenance, for the
use & maintenance phase, represent the greatest impact at 64 percent. The emission of other climate
change gases is insignificant by comparison. The impact from use (electricity) and maintenance (HFO) is
relatively even at 47 and 53 percent respectively. This highlights the significantly greater impact on climate
change of HFO combustion in relation to electricity, if the primary energy count is compared. The
installation and end-of-life phases are characterised by the same impacts to a lesser extent at 13 and 16
percent respectively. Analysis of the electricity mix used in this study, shows that production related CO2
emissions to air are greater for the US and China by a factor of 1.5 and 2.5 respectively, when compared
to production in the EU and Japan.
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7.3.6. Photochemical Ozone Creation
End of Life
Use & Maintenance
Installation
Manufacture
Raw Materials
0
0,000001
0,000002
0,000003
0,000004
0,000005
POCP (kg C2H4 eq.)
Figure 25: Photochemical ozone creation potential - per 10,000Gb·km.
As shown in Figure 25, photochemical ozone creation, or “summer smog”, is linked directly to the
combustion of heavy fuel oil (HFO) by ships and hence the use & maintenance phase dominates at 55
percent. As such the impact for the use & maintenance phase is related fully to cable maintenance. The
installation and end-of-life phases are similarly affected at 20 percent. Sulphur dioxide (SO2), nitrogen
oxides (NOx) and unspecified non-methane volatile organic compounds (NMVOC) are the significant
contributors from HFO combustion.
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A life cycle assessment of fibre optic submarine cable systems
7.3.7. Stratospheric Ozone Depletion
End of Life
Use & Maintenance
Installation
Manufacture
Raw Materials
0
1E-12
2E-12
3E-12
4E-12
5E-12
OD (kg CFC11 eq.)
Figure 26: Stratospheric ozone depletion potential - per 10,000Gb·km.
The release of halogenated organic (HO) emissions or CFCs, is the indicator for ozone layer depletion.
The production of raw materials dominates here at 51 percent, due to the release of HO emissions during
raw material processing, as shown in Figure 26. The production of silicon makes the significant
contribution (R11, R12 and R114) and, to a lesser extent, copper. The aluminium used for terminal
components releases halon during production. HO emissions are also released during the production of
heavy fuel oil (HFO), hence the relatively high impact of the installation, use & maintenance and end-oflife phases. Manufacturing, at 16 percent, is impacted by HFO production and also by halon released
during the production of thermal energy from gas. The cable and repeaters dominate the raw materials
phase accounting for 70 percent of the impact, while the cable dominates the use & maintenance phase
accounting for 100 percent of the impact.
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A life cycle assessment of fibre optic submarine cable systems
7.3.8. Eutrophication
End of Life
Use & Maintenance
Installation
Manufacture
Raw Materials
0
0,000002
0,000004
0,000006
0,000008
0,00001
EP (kg PO4 eq.)
Figure 27: Eutrophication potential - per 10,000Gb·km.
As presented in Figure 27, the use & maintenance phase dominates eutrophication at 56 percent, though
not as significantly as other categories. The principal indicator is nitrogen oxide (NOx) emissions from the
combustion of heavy fuel oil (HFO). This is reflected in the use & maintenance phase, where cable
maintenance by ship represents 90 percent of the impact. Similar to Acidification, the relatively high
values for the installation and end-of-life phases, at 20 percent, are linked directly to the HFO
consumption by the cable ship operations, presented in Figure 20.
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A life cycle assessment of fibre optic submarine cable systems
7.3.9. Human Toxicity
End of Life
Use & Maintenance
Installation
Manufacture
Raw Materials
0
0,0005
0,001
0,0015
0,002
HTP (kg 1,4DCB eq.)
Figure 28: Human toxicity potential - per 10,000Gb·km.
Emissions of heavy metals to water and air represent the major contribution to Human Toxicity. The
significant use of heavy fuel oil (HFO) and electricity during the use & maintenance phase results in the
greatest impact at 60 percent, as shown in Figure 28. Nickel and arsenic are the major contributors
resulting from the combustion of HFO during cable maintenance. Polycyclic aromatic hydrocarbon
(PAH) emissions to seawater, from the maintenance of the ship’s hull, have a lesser impact. These
combine to represent 72 percent of the impact for the use & maintenance phase. Selenium is the
significant contributors from the terminal station due to the production of electricity, though has a lesser
impact to cable maintenance by a factor of three. Again, the relatively high values for the installation and
end-of-life phases at 17 and 18 percent respectively, are linked directly to the HFO consumption by the
cable ship operations, presented in Figure 20.
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A life cycle assessment of fibre optic submarine cable systems
7.4. Results by Life Cycle Phases
The following section presents the results by life cycle phase and in relation to the functional unit of
10,000Gb·km. For each life cycle phase, the results are firstly presented for all impact categories in relation
to the sub-models of the cable, repeaters and the terminal station. Secondly, a more detailed analysis of the
components of these sub-models is undertaken based on the energy and resource use, acidification and
climate change. These areas are of particular interest to Ericsson in their research into the total carbon
footprint of the global ICT network and therefore, are the focus of this section. The results highlight the
general dominance of the impact from the cable in relation to the terminal station and the relatively
insignificant impact of the repeaters.
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A life cycle assessment of fibre optic submarine cable systems
7.4.1. Raw Materials
Primary Energy
Electricity
Heavy Fuel Oil
Abiotic Resource Depletion
Acidification Potential
Freshwater Aquatic Ecotoxicity Potential
Terrestric Ecotoxicity Potential
Marine Aquatic Ecotoxicity Potential
Global Warming Potential
Photochemical Ozone Creation Potential
Ozone Depletion Potential
Eutrophication Potential
Human Toxicity Potential
0%
20%
Cable
40%
60%
Repeaters
80%
100%
Terminal
Figure 29: Impact distribution for Raw Material sub-models.
Figure 29 shows that the raw materials sub-model for the cable clearly dominates the selected impact
categories at over 85 percent. This is traced to the bulk weight of the cable in relation to repeaters and the
terminal station. Resource depletion, energy consumption and climate change are shown to be closely
linked and relate primarily to the use of primary energy resources (oil, coal and natural gas) during raw
material production.
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A life cycle assessment of fibre optic submarine cable systems
0,002
8,00E-07
0,0018
7,00E-07
6,00E-07
0,0014
0,0012
5,00E-07
0,001
4,00E-07
0,0008
3,00E-07
0,0006
ADP (kg Sb eq.)
Primary Energy (MJ)
0,0016
2,00E-07
0,0004
0,0002
1,00E-07
0
0,00E+00
Primary Energy
Resources
Figure 30: Primary Energy verses Resource Depletion for selected raw material sub-models.
The link between energy consumption and resource depletion is clearly shown in Figure 30, and, is directly
linked to the use of primary energy resources (oil, coal and natural gas) during raw material production.
The cable visibly dominates over the repeater and terminal station sub-models. At only 3 percent of a
cable system, the relatively high energy and resource use for double armour (DA) cable reflects the large
material input, as shown in Figure 14.
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7. Results of Life Cycle Interpretation
A life cycle assessment of fibre optic submarine cable systems
0,002
7,00E-05
0,0018
6,00E-05
5,00E-05
0,0014
0,0012
4,00E-05
0,001
3,00E-05
0,0008
0,0006
2,00E-05
GWP100 (kg CO2 eq.)
Primary Energy (MJ)
0,0016
0,0004
1,00E-05
0,0002
0
0,00E+00
Primary Energy
Climate Change
Figure 31: Primary Energy verses Climate Change for selected raw material sub-models.
Carbon dioxide equivalent (CO2 eq.) emissions are directly linked to the use of primary energy resources
for the production of raw materials, as shown in Figure 31 . Silicone gel and galvanised steel wire
production, particularly, release large amounts of CO2. Again, the emissions from the cable raw materials
clearly dominates.
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7. Results of Life Cycle Interpretation
A life cycle assessment of fibre optic submarine cable systems
7.4.2. Design & Manufacturing
Primary Energy
Electricity
Heavy Fuel Oil
Abiotic Resource Depletion
Acidification Potential
Freshwater Aquatic Ecotoxicity Potential
Terrestrial Ecotoxicity Potential
Marine Aquatic Ecotoxicity Potential
Global Warming Potential
Photochemical Ozone Creation Potential
Ozone Depletion Potential
Eutrophication Potential
Human Toxicity Potential
0%
20%
Cable
40%
Repeaters
60%
80%
100%
Terminal
Figure 32: Impact distribution for Design & Manufacturing sub-models.
The result of the design & manufacturing sub-model reveals no clear structure across the selected impact
categories, as shown in Figure 32. Primary energy consumption is balanced between cable and terminal
and relates to the production of electricity for manufacturing of the cable and the terminal components,
particularly the printed board assembly (PBA). Manufacturing of the PBA consumes the greatest amount
of electricity, hence the dominance of the terminal sub-model at 45 percent and the relatively large
consumption of electricity (15 percent) by the repeater manufacture. Heavy fuel oil (HFO) is used
primarily for the cable route survey and a very small amount for the manufacturing of the terminal leadacid batteries. The combustion of HFO by the research ship is linked to climate change (global warming
potential) and is the principal cause for the greater impact of the cable sub-model at 78 percent.
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7. Results of Life Cycle Interpretation
A life cycle assessment of fibre optic submarine cable systems
0,0008
5,00E-05
0,0007
4,50E-05
4,00E-05
3,50E-05
0,0005
3,00E-05
0,0004
2,50E-05
0,0003
2,00E-05
1,50E-05
Electricity (kWh)
Primary Energy (MJ)
0,0006
0,0002
1,00E-05
0,0001
5,00E-06
0
0,00E+00
Primary Energy
Electricity
Figure 33: Primary Energy verses Electricity for selected manufacturing sub-models.
Figure 33 shows that the link between electricity consumption and primary energy is clearly apparent and
relates to the use of primary energy resources (oil, coal and natural gas) for electricity production. The
large energy consumption of the submarine line terminal equipment (SLTE) is related to the manufacture
of the PBA, particularly the integrated circuit (IC) chips. As mentioned in Section 4.4.3.3, this is likely to
be an over-estimation, though clearly dominates over the other components. The high primary energy
consumption during the route survey relates to heavy fuel oil (HFO) consumption.
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7. Results of Life Cycle Interpretation
A life cycle assessment of fibre optic submarine cable systems
0,0012
2,00E-04
1,80E-04
1,60E-04
1,40E-04
0,0008
1,20E-04
0,0006
1,00E-04
8,00E-05
0,0004
6,00E-05
GWP100 (kg CO2 eq.)
Primary Energy (MJ)
0,001
4,00E-05
0,0002
2,00E-05
0
0,00E+00
Primary Energy
Climate Change
Figure 34: Primary Energy verses Climate Change for selected manufacturing sub-models.
The large impact of the route survey on climate change highlights the significant effect of CO2 equivalent
emissions from the combustion of heavy fuel oil (HFO), as shown by Figure 34. By comparison, the
consumption of electricity has no impact on climate change. The production of electricity on the other
hand does have an impact, as highlighted by the lesser effect for all other components.
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A life cycle assessment of fibre optic submarine cable systems
7.4.3. Installation
Primary Energy
Electricity
Heavy Fuel Oil
Abiotic Resource Depletion
Acidification Potential
Freshwater Aquatic Ecotoxicity Potential
Terrestrial Ecotoxicity Potential
Marine Aquatic Ecotoxicity Potential
Global Warming Potential
Photochemical Ozone Creation Potential
Ozone Depletion Potential
Eutrophication Potential
Human Toxicity Potential
0%
20%
Cable
40%
60%
Repeaters
80%
100%
Terminal
Figure 35: Impact distribution for the Installation sub-models.
As discussed earlier, the installation of the terminal building has not been accounted for as it is assumed
that it does not make a significant contribution to the results. Repeaters are installed as part of the
processes of cable installation and cannot be accounted for separately. As such, cable installation by
purpose-built cable ship is the only sub-model accounted for under installation and hence represents the
total impact, as shown in Figure 35. Emissions from the combustion of heavy fuel oil (HFO) represent
the principal effect for the installation sub-model, with climate change and acidification as important
indicators due to the release of carbon dioxide (CO2) , sulphur dioxide (SO2) and nitrogen oxides (NOX).
78
A life cycle assessment of fibre optic submarine cable systems
0,0018
4,50E-04
0,0016
4,00E-04
0,0014
3,50E-04
0,0012
3,00E-04
0,001
2,50E-04
0,0008
2,00E-04
0,0006
1,50E-04
0,0004
1,00E-04
0,0002
5,00E-05
0
0,00E+00
In Port
Manoeuvring
Transit
Primary Energy
Air travel
GWP100 (kg CO2 eq.)
Primary Energy (MJ)
7. Results of Life Cycle Interpretation
Ship Hull
Climate Change
Figure 36: Primary Energy verses Climate Change for selected installation sub-models.
Figure 36 shows that primary energy consumption is related to the production of heavy fuel oil (HFO),
whilst climate change is related to the combustion of HFO. The greatest effect on climate change comes
from the emission of carbon dioxide (CO2) during the HFO combustion process. Air travel is shown to
have only a minor impact by comparison.
0,0018
1,40E-05
0,0016
1,20E-05
1,00E-05
0,0012
0,001
8,00E-06
0,0008
6,00E-06
0,0006
AP (kg SO2 eq.)
Primary Energy (MJ)
0,0014
4,00E-06
0,0004
2,00E-06
0,0002
0
0,00E+00
In Port
Manoeuvring
Transit
Primary Energy
Air travel
Ship Hull
Acidification
Figure 37: Primary Energy verses Acidification for selected installation sub-models.
Similar to climate change, Figure 37 shows that the acidification effect of heavy fuel oil (HFO)
combustion is clearly apparent. The main contribution comes from the emissions of sulphur dioxide (SO2)
and nitrogen oxides (NOX).
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A life cycle assessment of fibre optic submarine cable systems
7.4.4. Use & Maintenance
Primary Energy
Electricity
Heavy Fuel Oil
Abiotic Resource Depletion
Acidification Potential
Freshwater Aquatic Ecotoxicity Potential
Terrestrial Ecotoxicity Potential
Marine Aquatic Ecotoxicity Potential
Global Warming Potential
Photochemical Ozone Creation Potential
Ozone Depletion Potential
Eutrophication Potential
Human Toxicity Potential
0%
20%
40%
Cable
(Maintenance)
Repeaters
(Use)
60%
80%
100%
Terminal
(Use)
Figure 38: Impact distribution for the Use & Maintenance sub-models.
The results of the use & maintenance sub-model reveals the distinction between heavy fuel oil (HFO)
consumption during cable maintenance and electricity use at the terminal, as presented in Figure 38. By
comparison, electricity consumption by the cable is minor. Primary energy consumption at the terminal
dominates at 67 percent. However, the combustion of HFO results in a much greater impact on climate
change and more significantly, acidification. The global warming potential category (GWP100) shows that
emissions of carbon dioxide equivalents (CO2 eq.) are equally shared between use at the terminal (47
percent) and maintenance of the cable (53 percent). This is due to the greater emissions of carbon dioxide
(CO2), sulphur dioxide (SO2) and nitrogen oxides (NOX) from the combustion of HFO.
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A life cycle assessment of fibre optic submarine cable systems
0,04
2,50E-03
0,035
Primary Energy (MJ)
0,025
1,50E-03
0,02
1,00E-03
0,015
0,01
GWP100 (kg CO2 eq.)
2,00E-03
0,03
5,00E-04
0,005
0
0,00E+00
Primary Energy
Climate Change
Figure 39: Primary Energy verses Climate Change for selected use & maintenance sub-models.
The greater impact on climate change from the combustion of heavy fuel oil (HFO) is apparent in Figure
39. Whilst the terminal clearly consumes more primary energy, ship operations release more carbon
dioxide (CO2) emissions per unit of energy. Again, air travel results in a relatively minor impact.
0,04
3,50E-05
0,035
3,00E-05
2,50E-05
0,025
2,00E-05
0,02
1,50E-05
0,015
AP (kg SO2 eq.)
Primary Energy (MJ)
0,03
1,00E-05
0,01
0,005
5,00E-06
0
0,00E+00
Primary Energy
Acidification
Figure 40: Primary Energy verses Acidification for selected use & maintenance sub-models.
The impact of heavy fuel oil (HFO) combustion per unit energy input is even more apparent for
acidification, as shown in Figure 40. Ship operations clearly dominate the acidification impact. The main
contribution comes from the emission of sulphur dioxide (SO2) and nitrogen oxides (NOX) during the
combustion of HFO.
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A life cycle assessment of fibre optic submarine cable systems
0,01
0,000006
0,000005
0,000004
0,006
0,000003
0,004
HFO (MJ)
Electricity (MJ)
0,008
0,000002
0,002
0,000001
0
0
Cable
Repeaters
Electricity
Terminal
Heavy Fuel Oil
Figure 41: Electricity verses Heavy Fuel Oil for the use & maintenance sub-models.
0,04
4,00E-06
0,035
3,50E-06
0,03
3,00E-06
0,025
2,50E-06
0,02
2,00E-06
0,015
1,50E-06
0,01
1,00E-06
0,005
5,00E-07
0
0,00E+00
Primary Energy
EP (kg PO4 eq.)
Primary Energy (MJ)
The distinction between heavy fuel oil (HFO) consumption during cable maintenance and electricity use
at the terminal is apparent in Figure 41. By comparison, the cable itself uses little electricity.
Eutrophication Potential
Figure 42: Primary Energy verses Eutrophication the use & maintenance sub-models.
Figure 42 shows that the impact of heavy fuel oil (HFO) combustion per unit energy input is dominant
for eutrophication. Ship operations clearly dominate the eutrophication impact. The main contribution
comes from the emission of nitrogen oxides (NOX) during the combustion of HFO. Similarly the
emission of NOX from electricity production represents the main impact from the terminal station.
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A life cycle assessment of fibre optic submarine cable systems
0,04
3,00E-01
0,035
Primary Energy (MJ)
2,00E-01
0,025
0,02
1,50E-01
0,015
1,00E-01
0,01
MAETP (kg 1,4DCB eq.)
2,50E-01
0,03
5,00E-02
0,005
0
0,00E+00
Primary Energy
Marine Aquatic Ecotoxicity Potential
Figure 43: Primary Energy verses Marine Aquatic Ecotoxicity Potential for the use & maintenance sub-models.
Emissions of heavy metals represent the major contribution to marine aquatic ecotoxicity potential
(MAETP) and are dominant for the terminal station, as shown in Figure 43. Heavy metal emissions to
freshwater from electricity production are selenium in the greatest amount, with vanadium, nickel and
cobalt following. Maintenance of the ship’s hull releases copper in the greatest amount to seawater. The
impact from shipping activities is related primarily to nickel released to air from the combustion of heavy
fuel oil (HFO).
A review of the freshwater aquatic ecotoxicity potential (FAETP) results reveals a similar picture as
MAETP. Emissions of the same heavy metals to freshwater from electricity production represent the
major contribution from the terminal energy use. Again, the impact from shipping activities is related
primarily to nickel released to air from the combustion of HFO.
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A life cycle assessment of fibre optic submarine cable systems
7.4.5. End-of-Life Decommissioning
Primary Energy
Electricity
Heavy Fuel Oil
Abiotic Resource Depletion
Acidification Potential
Freshwater Aquatic Ecotoxicity Potential
Terrestrial Ecotoxicity Potential
Marine Aquatic Ecotoxicity Potential
Global Warming Potential
Photochemical Ozone Creation Potential
Ozone Depletion Potential
Eutrophication Potential
Human Toxicity Potential
0%
Recovery
20%
40%
Cable Materials
60%
Repeater Materials
80%
100%
Terminal Materials
Figure 44: Impact distribution for the end-of-life sub-models.
The end-of-life phase considers both recovery and recycling of the cable and recycling of some terminal
components. The system includes a simplified recycling model based on electricity consumption for
material reprocessing. Recovery is assumed to be the exact opposite of the installation process and
therefore has the same impacts as discussed in Section 7.4.3. The recycled cable materials are assumed to
offset 90 percent of the virgin material input. The results, presented in Figure 44, show the distinction
between the combustion of heavy fuel oil (HFO) during recovery and the use of electricity for material
reprocessing. As observed in the results for the use & maintenance phase, climate change and acidification
impacts are clearly affected by the combustion of HFO and the emissions of carbon dioxide (CO2),
sulphur dioxide (SO2) and nitrogen oxides (NOX). Recycling of the repeaters and terminal station
components has a minor effect by comparison.
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A life cycle assessment of fibre optic submarine cable systems
0,0045
1,00E-03
0,004
9,00E-04
0,0035
8,00E-04
7,00E-04
0,003
6,00E-04
0,0025
5,00E-04
0,002
4,00E-04
0,0015
3,00E-04
0,001
2,00E-04
0,0005
1,00E-04
0
0,00E+00
Recovery
Cable Materials
GWP100 (kg CO2 eq.)
Primary Energy (MJ)
7. Results of Life Cycle Interpretation
Repeater Materials Terminal Materials
Primary Energy
Climate Change
Figure 45: Primary Energy verses Climate Change for selected end-of-life sub-models.
Figure 45 shows that again, the greater impact on climate change from the combustion of heavy fuel oil
(HFO) is apparent. Whilst the recycling of cable materials consumes a relatively large amount of primary
energy, ship operations during recovery release significantly more carbon dioxide (CO2) emissions per unit
of energy. By comparison, the repeaters and terminal station recycling has little impact.
0,0045
3,00E-05
0,004
2,50E-05
0,003
2,00E-05
0,0025
1,50E-05
0,002
0,0015
1,00E-05
AP (kg SO2 eq.)
Primary Energy (MJ)
0,0035
0,001
5,00E-06
0,0005
0
0,00E+00
Recovery
Cable Materials
Repeater Materials
Primary Energy
Terminal Materials
Acidification
Figure 46: Primary Energy verses Acidification for selected end-of-life sub-models.
Similar to the use & maintenance phase, the impact of heavy fuel oil (HFO) combustion per unit of
primary energy input is even more apparent for acidification and is clearly dominated by the ship
operations, as shown in Figure 46. The main contributors are sulphur dioxide (SO2) and nitrogen oxides
(NOX) emissions.
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7. Results of Life Cycle Interpretation
A life cycle assessment of fibre optic submarine cable systems
0,0007
0,0000025
0,0006
0,000002
0,0000015
0,0004
0,0003
0,000001
HFO (MJ)
Electricity (MJ)
0,0005
0,0002
0,0000005
0,0001
0
0
Recovery
Cable Materials
Repeater Materials Terminal Materials
Electricity
HFO
Figure 47: Electricity verses heavy fuel oil for the end-of-life sub-models.
The distinction between heavy fuel oil (HFO) consumption during recovery operations and electricity
consumption during recycling is apparent in Figure 47. By comparison, repeater and terminal station
recycling uses little energy.
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7.5. Data Quality Analysis
This section details the data quality analysis undertaken to assess how uncertanties in the model may affect
the result. The data quality analyisis thereby gives an indication of the accuracy and robustness of the
model. Various scenarios were constructed based on the perceived importance of the process, data gaps or
where the quality of the data did not reach the required standard (ISO 14044:2006).
The results of the data quality analysis show that the model is relatively robust. The largest data gaps and
uncertainties are presented by the raw material and manufacturing phases for the repeaters and terminal
station equipment, which are shown to have no significant effect on the results. The greatest effect on the
model results from the use & maintenance phase relating to fuel combustion from ship activities and
electricity production. These processes are modelled on measured data from the literature and are
assumed to represent the system appropriately.
7.5.1. Sensitivity Analysis – Data gaps and uncertainties
The first part of the sensitivity analyisis was undertaken to assess how uncertanties and gaps in the data
may affect the result. Five scenarios were constructed and are detailed in Table 26.
Table 26: Description of sensitivity analysis (uncertainties and data gaps) scenarios
Name
Description
Motivation
Raw Transport at 500%
Road transportation of raw materials was increased by 500% from 1000km to
5000km to assess the impact of any likely under estimation.
Assumption/
Uncertainty
Recycling Transport at 1000%
Road transportation of materials for recycling was increased by 1000% from
100km to 1000km to assess the impact of any likely under estimation.
Assumption/
Uncertainty
Repeaters internal electronics
at 400%
The internal electronics modelled by an assumed comparable process of a printed
board assembly was increased from 8.5kg to 35kg to assess the impact.
Data gap /
Uncertainty
Repeaters raw materials,
Manufacturing and E-o-L at 0%
Repeaters were removed entirely from the model to test the impact of repeaters
on the final result.
Data gap
Terminal raw materials,
Manufacturing and E-o-L at 0%
The raw materials and manufacturing of the terminal station were moved from
the model.
Data gap /
Uncertainty
For each scenario, the studied input parameter was varied and the result recalculated. The results are given
as a percentage deviation for each impact category from the original result. The results are presented
graphically in Figure 48 and are tabluated in full in Appendix F.
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7. Results of Life Cycle Interpretation
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100%
80%
60%
40%
20%
0%
-20%
-40%
-60%
-80%
-100%
Primary Energy
Electricity
Heavy Fuel Oil
Abiotic Resource Depletion
Acidification Potential
Freshwater Aquatic Ecotoxicity Potential
Terrestric Ecotoxicity Potential
Marine Aquatic Ecotoxicity Potential
Global Warming Potential
Photochemical Ozone Creation Potential
Ozone Depletion Potential
Eutrophication Potential
Human Toxicity Potential
Figure 48: Results of sensitivity analysis (uncertainties and data gaps)
The results of the sensitivity analysis reveal that the processes considered to have the greatest uncertainty
for the raw materials, design & manufacturing and end-of-life phases have limited effect on the final
result.
Transportation of the raw materials was examined due to the uncertainty introduced by the assumption
that all raw materials were road transported 1,000 kilometres. Given the nature of the specialised
components, it is possible that this is an under estimate. The analysis shows that transport of raw materials
does not have a significant effect on the result. Increasing the road transport distance by 500 percent to
5,000 kilometres, results in an increase in impact from 0.05 to 2.1 percent over all categories. A similar
result is returned for the transport of materials to be recycled. Increasing the road transport distance by
1,000 percent from 100 to 1,000 kilometres, to account for any under estimate, results in an increase in
impact from 0.1 to 5.0 percent.
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A life cycle assessment of fibre optic submarine cable systems
With an estimated 200 submarine repeaters per 10,000 kilometres, it was assumed that repeaters would
make a significant contribution to the overall environmental impact of the cable. Repeaters represent a
data gap that resulted in assumptions being made from similar processes for all materials other than the
repeater housing, which was assumed to be beryllium copper alloy. Firstly, the assumption based on the
printed board assembly (PBA) was explored. Due to uncertainty in the assumption and a possible under
estimate, the amount of PBA in the repeater was increased from 8.5 kilograms to 35 kilograms. The
results show a minimal effect of approximately one percent. Secondly, the repeaters were removed from
the model entirely to test the effect on the result. Ozone depletion potential is reduced by 16 percent,
while all other impact categories are affected by less than 0.6 percent. The change in ozone depletion is
related mainly to the aluminium production process and the reduced raw material input. The process of
aluminium production is taken from the GaBi database and is assumed to be accurate.
A similar case is apparent for the removal of the terminal raw materials, design & manufacturing and endof-life phases. Ozone depletion potential is affected by 19 percent and linked mainly to the cabinets, both
the reduced aluminium input and to a lesser extent the thermal energy used during the manufacture
process. Again, aluminium and thermal energy production are taken from the GaBi database and assumed
to be accurate. All other categories were affected by less than 1.5 percent. Other than ozone depletion, the
sensitivity analysis shows that the assumptions made for the weight of PBA and cabinets contained within
a terminal do not significantly affect the results.
7.5.2. Sensitivity Analysis – Methodological Choices
The second part of the sensitivity analyisis was undertaken “to determine how changes in data and
methodological choices” may affect the result (ISO 14044:2006, p22). Various scenarios were constructed
based on identified key processes, particullary during the use & maintenance phase. The sensitivity analysis
scenarios are detailed in Table 27.
Table 27: Description of sensitivity analysis (methodological choices) scenarios
Name
Description
Motivation
Terminal Electricity at 70%
Terminal electricity consumption during the use phase was reduced by 30% to
assess the impact of any likely over estimation due to upgrading to more efficient
components.
Uncertainty
EU-25 electricity production
The electricity model was replaced by the standard database process for
electricity production in the EU-25 countries to assess the validity of the regional
model used in this study.
Key process
Cable Maintenance by ship at
150%
Annual maintenance (per 1000 kilometre) of the cable was increased from 7.41
ship days to 11.12 ship days.
Key process
Ship Emissions to Marine
Distillate fuel
Emission factors for ships were changed from heavy residual oil (RO) to the less
utilised, yet cleaner marine distillates (MD).
Key process
Lifetime 25 years at
10000Gb.km relative
The results of the 25 year technical lifetime of the cable were assessed relative to
the functional unit of 10000Gb·km of cable and compared to the original case.
Key process
No recovery at E-o-L
The end-of-life phase undertaking recovery and recycling of the cable was
removed from the model, thereby increasing the raw material input to 100%.
Key process
For each scenario, the studied input parameter was varied and the result recalculated. The results are given
as a percentage deviation for each impact category from the original result. The results are presented
graphically in Figure 49 and are tabluated in full in
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7. Results of Life Cycle Interpretation
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100%
80%
60%
40%
20%
0%
-20%
-40%
-60%
-80%
-100%
Primary Energy
Abiotic Resource Depletion
Terrestric Ecotoxicity Potential
Photochemical Ozone Creation Potential
Human Toxicity Potential
Electricity
Acidification Potential
Marine Aquatic Ecotoxicity Potential
Ozone Depletion Potential
Heavy Fuel Oil
Freshwater Aquatic Ecotoxicity Potential
Global Warming Potential
Eutrophication Potential
Figure 49: Results of sensitivity analysis (methodological choices)
The results of the sensitivity analysis reveal that the activities and methodological assumptions made for
the use & maintenance phase affect the model significantly.
Electricity consumption at the terminal during the use & maintenance phase was examined due to the
large impact generated, as shown in Section 7.4.4. Whilst the energy consumption is considered to be well
defined, based on the actual usage at two terminals (with good agreement), it was interesting to consider
the impact of potential energy savings due to the upgrading of terminal components. As such, electricity
consumption at the terminal was reduced by 30 percent. All resultant changes are directly related to the
production of electricity. The largest effect was to freshwater aquatic ecotoxicity at 21 percent, which is
linked to the release of heavy metals to freshwater. Marine aquatic ecotoxicity at 14 percent and terrestrial
ecotoxicity at 9 percent change are also directly affected by the release of heavy metals. Resource depletion
is affected by 15 percent, linked to the use of primary energy resources, such as crude oil and coal. Climate
change potential is affected by 9 percent related to carbon dioxide and methane emissions. Less significant
change is observed in all other impact categories.
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A life cycle assessment of fibre optic submarine cable systems
In order to assess the validity of the regional electricity mix modelled by a previous study at Ericsson, the
electricity sub-model was changed to the standard database process for the EU-25 countries. No process
was available in the GaBi software that modelled a world electricity mix, therefore the EU-25 production
process was selected. The most significant change relates to ozone depletion potential category at a
relative increase of 5000 percent and relates directly to the emissions of CFC gases. Secondly, marine
aquatic ecotoxicity potential (MAETP) results in a 65 percent increase. This relates primarily to the
emission to air of hydrogen fluoride, which dominates the EU-25 impacts and is not modelled in the
Ericsson regional sub-models. In contrast, the Ericsson study models a far greater amount of heavy metal
emissions to freshwater based on regional differences in production. Freshwater aquatic ecotoxicity
potential (FAETP) is reduced by 76 percent, which relates directly to the modelling of heavy metal
emissions to freshwater. These emissions are greater by a factor of 45 in the Ericsson study when
compared to the EU-25 production process. Primary energy is reduced by 13 percent and abiotic resource
depletion by 19 percent. With the exception of terrestrial ecotoxicity potential (TETP) at 21 percent, all
other categories show a change of less than 15 percent. The Ericsson study is based on extensive research
into the regional differences in electricity production (3GLCA, 2002), while the assumptions and data
source of the EU-25 standard database process are unknown. The differences in impact between the two
electricity production methods likely reflects these regional differences and the differences in data sources.
Shipping activities are identified to be key processes over the 13 year lifetime of the cable. The analysis
shows that a 50 percent increase in the annual maintenance (per 1,000 kilometres) with ships from 7.41
ship days to 11.12 ship days, results in significant increase in almost all impact categories. Acidification and
eutrophication are both affected by 25 percent and are directly linked to fuel combustion and the
emissions thereof, particularly sulphur dioxide (SO2) and nitrogen oxides (NOX). Climate change is
affected by 17 percent directly linked to carbon dioxide (CO2) emissions. Emission factors are based on
the more conservative figures for the heavier residual oil (RO) emissions. When these are replaced with
emissions factors for the cleaner marine distillates (MD), the results are again significantly affected. A
comparison of the emission factors can be found in Cooper and Gustafsson (2004). Human toxicity,
terrestrial ecotoxicity and photochemical ozone creation are reduced by between 43 to 69 percent, linked
to the reduced emissions of heavy metals. Acidification is reduced by 47 percent, primarily linked to the
reduction of SO2 and NOX. In contrast, the impact on climate change is increased by 2% given the slight
increase in the emission of CO2. The results of these two sensitivity analyses highlight the significant affect
of shipping on the overall environmental impact of the cable system. The number of maintenance days
(normalised to 1000 kilometres of cable) is calculated from actual data for standby and operation times.
An assumption is made for the operation mode (transit, manoeuvring, in port) during repair operations,
however this is not considered to introduce significant uncertainty into the results. Emission factors for
ships are well established from the literature. The use of RO emission factors increases the impact
significantly for the majority of categories, however RO is the most frequently used fuel in the shipping
industry and accounts for the worst case scenario, therefore, is considered appropriate.
The use & maintenance period for the cable is shown to dominate the impact in almost all categories.
Consequently, it is appropriate to investigate how the result is affected if the lifetime of the cable is
increased from the commercial lifetime of 13 years to the documented technical lifetime of 25 years. All
impacts, excluding ozone depletion, were reduced by between 4 and 23 percent. Ozone depletion was
affected by 39 percent due to the high influence of raw material production on this impact category. The
results clearly highlight the reduced environmental impact of increasing the in-service lifetime of the cable.
A sensitivity analysis was undertaken on the effect of simply abandoning the cable at decommissioning,
resulting in no end-of-life impacts, yet requiring 100 percent virgin material input. The analysis shows that
ozone depletion is affected significantly at 126 percent, due the influence of the processing of raw
materials on this impact category. Surprisingly, with an increase in virgin materials from 10 to 100 percent,
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resource depletion is increased by only 6 percent and primary energy by 3 percent. Electricity is reduced
by 3 percent and heavy fuel oil (HFO) is reduced by 23 percent. Electricity and HFO are somewhat
problematic for the raw materials phase as they are not tracked in the standard database processes. What is
further surprising is that the impacts for all other categories are reduced by between 1 and 19 percent.
This reduction is related to the removal of the end-of-life phase and the reduction of impacts from fuel
combustion during recovery and electricity consumption during the recycling process, which appear to
have a greater impact than raw material processing.
7.6. Normalisation
The results of the normalisation calculation illustrate the comparison between the annual environmental
impact of one person’s data traffic in relation to the total annual environmental impact determined by the
normalisation factors presented in Section 5.4.
In order to perform the normalisation calculation, based on the annual environmental impact, the annual
per capita usage of a submarine cable system must first be estimated. Cisco Systems track and forecast the
global IP traffic and estimate that 50 exabytes (50 x 1018 EB) of data was sent during 2006 (Cisco, 2008).
They also predict that global IP traffic will grow rapidly, driven by internet video. Dividing the global IP
traffic by the total world population of 6.12 billion (UN, 2009), an average figure of 8.7 gigabytes (GB) of
data are sent annually per person. While it is unlikely that all of this data would pass through the
submarine network, for the purpose of normalisation, it is assumed that the total 50EB of data is
transferred via a submarine cable. As a comparison, the data traffic generated by the average US adult is
also estimated. Cisco (2008, p14) state that the “average US adult consumes the equivalent of nearly 120
GB per month.” This translates to an annual consumption of 1440GB of data. Again, it is assumed that all
of this data is sent, at some point, via a submarine cable. These two usage figures (8.7GB and 1440GB)
have then applied been to the results to estimate the potential environmental impact of one person’s
annual use of a submarine cable. It is assumed that this data is sent over 10,000 kilometres of cable,
thereby relating to 1Gb or 0.125GB of data (accepting 1 byte equals 8 bits).
The results of the normalisation calculation are presented in Table 28 and are expressed as a percentage of
the total annual environmental impact per capita, globally. Again, the results are only presented for the
three impact categories with the greatest certainty, as presented by Sleeswijk et al (2008).
Table 28: Normalisation results per person per year for 10,000km of cable.
Worldwide average
(8.7GB/person/year)
US average
(1440GB/person/year)
Acidification (500 years)
0.16%
2.6%
Global Warming (100 years)
0.007%
1.2%
Photochemical Ozone Creation
0.001%
0.15%
Impact Category
The results of the normalisation show a relatively low normalised impact. If the annual data consumption
of the average US adult is sent via submarine cable, then the potential acidification impact is calculated at
2.6 percent of their total potential annual impact. For climate change and photochemical ozone creation,
the figure is even less at 1.2 and 0.15 percent respectively. Accepting the limitation of the normalisation
calculation, these figures indicate that sending data via submarine cables has a very low potential
environmental impact in relation to the background impact of the two groups.
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8. Discussion
A life cycle assessment of fibre optic submarine cable systems
8. Discussion
This section presents a discussion of the important issues based on the results of this study.
The results show that the use & maintenance phase clearly dominates all impact categories at an average
of 66 percent. By comparison, the raw materials and design & manufacturing phases account for, on
average, only 6 percent of the total potential impact. This clearly highlights that the greatest impact over
the life cycle of a submarine cable system comes from the use & maintenance activities. Namely, electricity
use at the terminal to power the terminal equipment and the combustion of marine fuel during cable
maintenance with purpose-built ships. These are two key activities relating to the environmental
performance of the cable system. Ericsson has a particular focus on climate change and analysis of the
global warming potential (GWP100) impact category for the use & maintenance phase, shows that the
emissions of carbon dioxide equivalents (CO2 eq.) are equally shared between use at the terminal (47
percent) and maintenance of the cable (53 percent). However, the impact, per unit of primary energy
input, from the combustion of marine fuel oil has a far greater impact on climate change than the impact
from electricity use. This reflects the disparity in the environmental impacts of electricity and fossil fuel
consumption. The process of electricity production is modelled on the four regional models from the
Ericsson database. The effect on the result of using this mix has been explored in the sensitivity analysis,
which shows that regional differences in electricity production do have a significant weight on the final
result. Heavy use of coal for production, in both China and the US, is likely to be balanced against the
cleaner production of Japan and the EU. The regional mix from the Ericsson database is considered
robust and appropriate for this study. If however, the aim is to reduce the environmental burden of a
cable system further, then electricity produced from renewable sources could be considered by cable
owners. Submarine cable terminal stations are, by nature, close to the coast and in some regions, there
may be a possibility to take advantage of renewable energy generated by wind, wave and tidal streams. It is
not within the scope of this study, to assess the potential reduction in impact this could bring, however,
this could be an area for future study.
The production of heavy fuel oil (HFO), on the other hand, is biased toward US and EU production and
is likely to be a best case scenario. Adding production processes from other regions would strengthen the
LCA model, however this data was not available. Nevertheless, the results show that it is emissions from
the combustion of HFO that have a greater impact on the final result. Combustion emissions are well
modelled in the literature and it is more the methodological choice of using residual oil (RO) emission
factors than the cleaner marine distillates (MDs) factors that significantly affects the results. Acidification
and photochemical ozone creation are two impact categories, particularly affected by a reduction of over
40 percent, while climate change is relatively unchanged. This is linked directly to the low sulphur content
of the MD fuels, while the release of carbon dioxide (CO2) from combustion remains largely the same.
The calculation of fuel consumption for the average cable ship is based on the fleet of one particular
company. This company actually uses the cleaner MD fuels, therefore, emission reductions are currently
being made in this area. However, the majority of the world’s shipping fleet use the heavier residual oil
(RO) fuels and therefore, the emission factors for RO fuel have been used in this study, allowing for a
worst case scenario with regard to the impacts from shipping. Nitrogen oxide (NOx) controls on ships are
also another solution to reduce ship emissions, though they have not been considered by this study as they
are not common in older ships. If however, the focus is on climate change, then both fuels have similar
emissions of carbon dioxide equivalents (CO2 eq.) and hence similar environmental burdens.
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8. Discussion
A life cycle assessment of fibre optic submarine cable systems
These processes of electricity production, HFO production and HFO combustion have the greatest affect
on the result and as such, are the areas where future improvement of the model could be focused and the
greatest gains could be made in improving the environmental performance of the cable systems per unit
of data.
By comparison, the low impact for the raw materials and the design & manufacture phases, at only 6
percent of the total impact, is reflected partly in the recycling of the cable materials and partly in the
simplified manufacturing sub-model for the cable. Recycling of the cable materials accounts for 90 percent
of the virgin material input, thereby, providing a significant reduction in the impact from extraction and
processing of the raw materials. However this gain is offset by the recovery and recycling processes, which
have a greater environmental burden in relation to the extraction and processing of the equivalent 90
percent of raw materials. The sensitivity analysis for the end-of-life phase highlights this slightly poorer
environmental performance for the recovery and recycling scenario in relation to simple decommissioning
and abandonment. With increasing environmental accountability and likely increases in commodity prices,
it is expected that recovery and recycling of cables will become more common. Also, tests have shown
that recovery and reuse of the system is achievable, thereby substituting the raw materials and
manufacturing process completely. Some uncertainty does exist in this sub-model as the recycling process
is simplified to the electricity usage for recycling of the various materials. No emissions, other than those
from electricity production, are accounted for. This represents a possible under estimation, however, it is
likely that the emissions from electricity production represent the greatest impact on a global scale. Given
the slightly poorer environmental performance of cable recovery and recycling, it is still considered
appropriate to base the model on this scenario. Likewise, the manufacturing process of the cable is
simplified to the electricity consumption of the specific plant used to assemble the cable. No allocation of
the total emissions from the cable factory has been attempted, therefore, the manufacturing process is also
likely to be an underestimation. Though, based on the site visit to the cable manufacturing plant, cable
assembly is a relatively simple and benign process with few emissions. Again, it is likely that the emissions
from electricity production represent the greatest impact. Emissions from the manufacturing and the endof-life recycling processes are another area where future improvement of the model could be achieved.
Upgrading plays a significant role in magnitude of the potential impacts and is connected to the usage of
the cable. Modern systems are designed to be upgraded without replacing the cable itself. Upgrading
increases the system capacity by replacing transmission and receive components at the terminal station.
This study accounted for three upgrades over the system lifetime in a simplified linear model based solely
on the material and energy consumption of component manufacturing. While the literature shows that, on
average, 85 percent of the design capacity is currently not lit, no attempt was made in this study to assess
the impact based on an increased capacity due to this significant future upgrading potential. It has been
stated that technology is moving rapidly from 10Gbps to 40Gbps transmission, with commercialisation of
the later likely soon. While the overall environmental impact of the cable system over its lifetime would
not change significantly, clearly this will have a significant effect on reducing the environmental burden
per unit of data. Assuming that the energy consumption remains the same at the terminal station, then the
impacts would be reduced by a factor of four. With the leap to 40Gbps, it may be that cables remain in
service longer than 13 years as the maintenance costs per unit of data are reduced. Or perhaps, the extra
bandwidth may simply be soaked up by the expanding digital video market and greater consumer demand
as predicted by Cisco. With greater capacity the impact in relation to the functional unit of 10,000Gb·km
would be greatly reduced, however, the actual normalised impact per capita may not change significantly
as our personal data consumption is likely to increase in line with the available capacity.
As the functional unit is based on usage, the gap between lit capacity and usage affects the environmental
performance of the system. It is shown that on average, 25 percent of the current installed capacity is
actually used. The same energy is consumed if the cable is utilised at 25 percent capacity, or if it is
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8. Discussion
A life cycle assessment of fibre optic submarine cable systems
exploited to its full capacity. The maintenance requirements with ships are the same, as are the energy
requirements of the land terminal station. Therefore, subject to technical and commercial limitations, if
this gap between usage and lit capacity was reduced, a subsequent gain in environmental performance per
data unit would be achieved. Furthermore, increased system usage, in this case increased total data traffic,
reduces the resulting potential environmental impacts. The sensitivity analysis supports this conclusion
and shows that increasing system usage over the 25 year technical lifetime of a submarine cable system
reduces the potential environmental impact. From a life cycle perspective, the longer a cable remains in
service, the superior the environmental performance per unit of data. Used capacity and service life
therefore have a significant effect on the results and are the two key areas that affect the resulting
environmental impacts per unit of data.
The sensitivity analysis reveals how the limitations of the study affect the final result. Data gaps, data
uncertainty and methodological choices have been analysed to determine their effect. Repeaters represent
a total data gap, which has been filled by assumptions with regards to similar processes. The terminal
station model was constructed from similar processes from previous studies. Furthermore, the
components of the terminal have been estimated from a terminal specification from the year 2000. As
such, there is likely to be some over estimation, principally in the construction of the submarine line
terminal equipment (SLTE) sub-model. It has been shown that the technology is moving fast, and it is
likely that during the last nine years, efficiencies in equipment size and energy consumption have been
made. Methodological choices made in this study have an effect with regard to electricity production,
heavy fuel oil combustion (HFO) and commercial lifetime of the cable. The sensitivity analysis shows
however, that the effect of the most significant assumptions and limitations on the final result are not
particularly significant and that the effect of the methodological choices is approximately 20 percent over
all categories. This indicates that the model is relatively robust.
The results of the normalisation calculation show that the relative per capita environmental burden is
small for global warming and photochemical ozone creation. Acidification is slightly higher and is related
to the combustion of marine fuel. As explained earlier in the discussion, the methodological choice of
using the high sulphur content fuels directly affects the acidification impact category and thus similarly
affects the normalisation results.
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9. Conclusion
A life cycle assessment of fibre optic submarine cable systems
9. Conclusions
This Life Cycle Assessment (LCA) has been undertaken in order to fill, what appears to be, a gap in
knowledge regarding the environmental impacts of a submarine cable system. Submarine cable systems
make it possible to transfer large amounts of data around the globe almost instantaneously, yet, little was
known about the potential environmental impacts from a life cycle perspective. The main conclusions
from this study are:
•
The use & maintenance phase of the life cycle of a submarine cable system clearly dominates the
potential environmental impacts at an average of 66 percent.
•
The key potential impacts result from electricity use at the terminal and the combustion of marine
fuel onboard the cable ship during the cable maintenance. For climate change, these are roughly
balanced at 47 and 53 percent respectively.
•
Maintenance of the cable has the greatest impact on climate change per unit of primary energy
due to the emissions from the combustion of marine fuel onboard the cable ship.
•
Seven grams of carbon dioxide equivalents (7g CO2 eq.) are released per 10,000 gigabit kilometres
(Gb.km).
•
Based on the functional unit of sending data over the cable system, increasing the commercial
lifetime of a system or increasing data traffic through greater used bandwidth, reduces the
environmental impact per unit of data.
•
The data quality analysis shows that the most significant data gaps and uncertainties in the LCA
model do not affect the result significantly. Methodological choices affect the LCA model by
approximately 20 percent. This indicates that the model is relatively robust.
•
Normalisation shows a small relative impact when compared to the annual global impact per
person.
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10. Recommendations
A life cycle assessment of fibre optic submarine cable systems
10.Recommendations and Future Improvements and Use of the Model
The results show that sending data via submarine cable has a low environmental impact in relation to the
normalised impact on a global scale. However, if the aim is to reduce the environmental impact of these
systems further, then the use & maintenance phase is the area where companies should focus their efforts.
In particular, electricity use at the terminal and the emissions from the cable ships. The greatest gain is
likely to be achieved with the reduction of ship emissions as these appear to have the most significant
impact per unit of primary energy. Service lifetime and used bandwidth are also key parameters. An
increase in either results in a corresponding decrease in the potential impact per unit of data. These are
particular areas where cable owners could focus if environmental improvement is a goal.
The regional electricity models from the 3GLCA database could be revised to assess if the emissions of
CFC gases resulting in potential ozone depletion are modelled sufficiently. This impact category presented
the greatest change in the sensitivity analysis at 5000 percent. These models could also be updated with
current production figures. All other changes in relation to the sensitivity variables were within acceptable
and reasonable limits.
Improvements in the LCA model, for this study, should focus on improving the electricity production and
the heavy fuel oil (HFO) production sub-models. Modelling of HFO could be expanded to provide a
more reliable result based on a world production mix. Daily fuel consumption figures could also be
strengthened with data from other companies operating cable ships. These are two key processes within
the LCA model. Other areas include the data gaps and the assumptions made regarding similar processes
from previous LCA studies, which represent uncertainty in the model. The most significant data gap
relates to the submarine repeaters. Uncertainty in the terminal equipment could be reduced with a more
up-to-date specification of a modern terminal system. The current terminal specification was from the
year 2000 and much is likely to have changed in the following decade regarding size and efficiency of the
submarine line terminal equipment (SLTE). The recycling model could be expanded to include wastes and
emissions from the various material recycling processes. This would reduce uncertainty in the end-of-life
phase and provide a more certain comparison to the “no recovery” scenario, where 100 percent virgin
material is used for the system. Likewise, modelling of emissions and wastes from cable manufacturing
could be enhanced.
Accepting the assumptions and delimitations of this study, the submarine cable LCA model can be used to
predict the potential impacts of more specific cable systems. Two sub-models for the cable and the
terminal station were developed in parallel to allow for versatility and scaling of the system based on the
length of cable and the number of terminals. With this achieved, the actual used capacity of the specific
system could be applied to provide a more precise impact result per functional unit.
This study represents a snapshot of the potential environmental impacts based on today’s technology. It is
also a simplification of reality and these points must be taken into consideration when interpreting the
results.
97
11. Terminology
A life cycle assessment of fibre optic submarine cable systems
11.Terminology
1,4DCB
1,4 Dichlorobenzene
Mbps
Megabits per second
3G
Third Generation (mobile telephone network)
MD
Marine Distillates
A
Ampere
ME
Main Engine
AC
Alternating Current
MGO
Marine Gas Oil
ADP
Abiotic Depletion Potential
MJ
Megajoules
AE
Auxiliary Engine
NME
Network Management Equipment
AP
Acidification Potential
NMVOC
Non-Methane Volatile Organic Compound
BeCu
Beryllium Copper Alloy
NOx
Nitrogen Oxides (gases)
CML
ODP
Ozone Depletion Potential
CO
Institute of Environmental Sciences, University of
Leiden
Carbon Monoxide
PAH
Polycyclic Aromatic Hydrocarbons
CO2
Carbon Dioxide
PC
Personal Computer
DA
Double Armour (cable)
PFE
Power Feed Equipment
DC
Direct Current
pkm
Person Kilometre
EAF
Electric Arc Furnace
PM
Particle Matter
EB
Exabytes
PO4
Phosphate
EP
Eutrophication Potential
POCP
Photochemical Ozone Creation Potential
eq.
Equivalent
RO
Residual Oil
EU
European Union
SA
Single Armour (cable)
IP
Internet Protocol
SAT-1
South Atlantic (Cable No:) 1
ISO
International Organisation for Standardisation
Sb
Antimony (metal)
kbps
Kilobits per second
SDH
Synchronous Digital Hierarchy
kg
Kilogram
SLTE
Submarine Line Terminal Equipment
km
Kilometres
SO2
Sulphur Dioxide (gas)
KTH
Kungliga Tekniska högskolan
SOx
Sulphur Dioxides (gases)
kV
Kilovolts
t
tonne
kW
Kilowatt
TAT-14
Trans-Atlantic Telephone (Cable No:)14
kWh
Kilowatt hour
TETP
Terrestrial Ecotoxicity Potential
LCA
Life Cycle Assessment
TLA
Terminal Line Amplifier
LCI
Life Cycle Inventory
UK
United Kingdom
LCIA
Life Cycle Impact Assessment
US
United States (of America)
LME
Line Monitoring Equipment
V
Volt
LW
Lightweight (cable)
VOCs
Volatile Organic Compounds
LWP
Lightweight Protected (cable)
WDM
Wave Division Multiplexing
m
Metres
Wh
Watt hour
MAETP
Marine Aquatic Ecotoxicity Potential
WTE
Wave Terminating Equipment
98
12. List of Tables
A life cycle assessment of fibre optic submarine cable systems
12.List of Tables
Table 1: Comparison between satellite and submarine cable communication (Adapted from Barattino and Koopalethes, 2007;
NEC, 2008)................................................................................................................................................................................................................. 15
Table 2: Additional categories used for the life cycle impact analysis. ........................................................................................................... 21
Table 3: Distribution of electricity generation processes (Adapted from 3GLCA, 2002; Bergelin, 2008).............................................. 28
Table 4: Selected engine emission factors (g/kWh) for Residual Oils (Cooper and Gustafsson, 2004). ................................................ 30
Table 5: Average Cable Ship engine load characteristics by operational mode. (Cooper and Gustafsson, 2004) ................................. 31
Table 6: Ratio of cable types in the generic system. ........................................................................................................................................... 33
Table 7: Estimated weights of terminal components. ........................................................................................................................................ 36
Table 8: Engine Power: Average Research Ship (calculated from GMSL, 2009; confidential source). ................................................... 37
Table 9: Daily Fuel Consumption: Average Research Ship (calculated from confidential source). ......................................................... 38
Table 10: Average Research Ship: typical survey mission normalised to 1,000km of cable (calculated from confidential source). .. 38
Table 11: Engine Power: Average Cable Ship (calculated from GMSL, 2009). ........................................................................................... 41
Table 12: Daily Fuel Consumption: Average Cable Ship (calculated from GMSL, 2009). ........................................................................ 41
Table 13: Average Cable Ship: typical installation mission normalised to 1,000km of cable (calculated from confidential source). 41
Table 14: Average Cable Ship: Estimated operation mode per cable repair. ................................................................................................ 43
Table 15: Average Cable Ship: Annual repair mission normalised to 1,000km of cable (confidential source). ..................................... 43
Table 16: Energy consumption – steel recycling process (Jones, 2009; BlueScope, 2009; Corus, 2007; World Steel, 2008). ............. 45
Table 17: Energy consumption – aluminium recycling process (Green, 2007; Schmitz et al, 2006). ....................................................... 46
Table 18: LCI result summary for submarine cable system .............................................................................................................................. 48
Table 19: CML impact categories used for the life cycle impact analysis (Adapted from Guinée et al, 2004). ...................................... 51
Table 20: World normalisation factors, person equivalents per year (Adapted from Sleeswijk et al, 2008). ........................................... 54
Table 21: Calculation summary for the generic cable system (Adapted from Ruddy, 2006). .................................................................... 55
Table 22: Summary of capacity calculation for the generic cable system (Adapted from Ruddy, 2006). ................................................ 56
Table 23: Summary of results – per 10,000Gb·km. ........................................................................................................................................... 59
Table 24: Comparison of results – Climate change: Example 1 (Adapted from 3GLCA, 2002; European Commission, 2007;
Jonsson, 2009b). ........................................................................................................................................................................................................ 60
Table 25: Comparison of results – Climate change: Example 2 - Single person, 2 day meeting. (Adapted from 3GLCA, 2002;
Jonsson, 2009b). ........................................................................................................................................................................................................ 60
Table 26: Description of sensitivity analysis (uncertainties and data gaps) scenarios .................................................................................. 87
Table 27: Description of sensitivity analysis (methodological choices) scenarios ........................................................................................ 89
Table 28: Normalisation results per person per year for 10,000km of cable. ............................................................................................... 92
99
13. List of Figures
A life cycle assessment of fibre optic submarine cable systems
13.List of Figures
Figure 1: Report structure.......................................................................................................................................................................................... 3
Figure 2: LCA stages (ISO 14040:2006, p8) .......................................................................................................................................................... 4
Figure 3: World map of submarine cables (Alcatel, 2009) .................................................................................................................................. 7
Figure 4: Development of submarine cables (Hilt, 2009) ................................................................................................................................... 8
Figure 5: Unrepeated "festoon" system (adapted from Alcatel, 2009) ............................................................................................................. 9
Figure 6: Branched system architecture (adapted from Alcatel, 2009) ........................................................................................................... 10
Figure 7: Ring system architecture (adapted from Alcatel, 2009) .................................................................................................................... 10
Figure 8: Components of a submarine cable system (Letellier, 2004) ............................................................................................................ 11
Figure 9: Types of submarine cable: Double Armoured (DA), Single Armoured (SA), Lightweight Protected (LWP) and
Lightweight (LW) (Beaufils, 2000). ........................................................................................................................................................................ 12
Figure 10: Architecture of the SLTE (Breverman et al, 2007) .......................................................................................................................... 13
Figure 11: Life Cycle stages of a submarine cable (Adapted from USEPA, 2006). ..................................................................................... 17
Figure 12. Graphical representation in GaBi, built on a modular system (PE & LBP,2009). ................................................................... 22
Figure 13: Basic structure of the life cycle of a submarine cable system........................................................................................................ 25
Figure 14: Total weight verses weight of steel per 1,000 metres of cable. ..................................................................................................... 32
Figure 15: Distribution of all other raw materials (excluding steel) by cable type. ...................................................................................... 33
Figure 16: Distribution of raw materials in the terminal station. ..................................................................................................................... 35
Figure 17: Diagram of Submarine Line Terminal Equipment (SLTE) (Adapted from Markow, 2009).................................................. 36
Figure 18: Summary of results – per 10,000Gb·km. .......................................................................................................................................... 58
Figure 19: Primary Energy vs. Electricity consumption - per 10,000Gb·km................................................................................................ 61
Figure 20: Primary Energy vs. Heavy Fuel Oil consumption – per 10,000Gb·km. .................................................................................... 62
Figure 21: Abiotic resource depletion potential - per 10,000Gb·km. ............................................................................................................. 63
Figure 22: Acidification potential - per 10,000Gb·km....................................................................................................................................... 64
Figure 23: Ecotoxicity potential - per 10,000Gb·km. ........................................................................................................................................ 65
Figure 24: Climate change potential - per 10,000Gb·km. ................................................................................................................................. 66
Figure 25: Photochemical ozone creation potential - per 10,000Gb·km. ...................................................................................................... 67
Figure 26: Stratospheric ozone depletion potential - per 10,000Gb·km........................................................................................................ 68
Figure 27: Eutrophication potential - per 10,000Gb·km. ................................................................................................................................. 69
Figure 28: Human toxicity potential - per 10,000Gb·km.................................................................................................................................. 70
Figure 29: Impact distribution for Raw Material sub-models. ......................................................................................................................... 72
Figure 30: Primary Energy verses Resource Depletion for selected raw material sub-models.................................................................. 73
Figure 31: Primary Energy verses Climate Change for selected raw material sub-models. ........................................................................ 74
Figure 32: Impact distribution for Design & Manufacturing sub-models. .................................................................................................... 75
Figure 33: Primary Energy verses Electricity for selected manufacturing sub-models. .............................................................................. 76
Figure 34: Primary Energy verses Climate Change for selected manufacturing sub-models. .................................................................... 77
Figure 35: Impact distribution for the Installation sub-models. ...................................................................................................................... 78
Figure 36: Primary Energy verses Climate Change for selected installation sub-models. .......................................................................... 79
Figure 37: Primary Energy verses Acidification for selected installation sub-models. ................................................................................ 79
Figure 38: Impact distribution for the Use & Maintenance sub-models. ...................................................................................................... 80
Figure 39: Primary Energy verses Climate Change for selected use & maintenance sub-models. ........................................................... 81
Figure 40: Primary Energy verses Acidification for selected use & maintenance sub-models. ................................................................. 81
Figure 41: Electricity verses Heavy Fuel Oil for the use & maintenance sub-models. ............................................................................... 82
Figure 42: Primary Energy verses Eutrophication the use & maintenance sub-models. ............................................................................ 82
Figure 43: Primary Energy verses Marine Aquatic Ecotoxicity Potential for the use & maintenance sub-models............................... 83
Figure 44: Impact distribution for the end-of-life sub-models. ....................................................................................................................... 84
Figure 45: Primary Energy verses Climate Change for selected end-of-life sub-models. ........................................................................... 85
Figure 46: Primary Energy verses Acidification for selected end-of-life sub-models. ................................................................................ 85
Figure 47: Electricity verses heavy fuel oil for the end-of-life sub-models. .................................................................................................. 86
Figure 48: Results of sensitivity analysis (uncertainties and data gaps)........................................................................................................... 88
Figure 49: Results of sensitivity analysis (methodological choices) ................................................................................................................. 90
100
14. References
A life cycle assessment of fibre optic submarine cable systems
14.References
14.1.
Public References
ABB, 2009a. Environmental Product Declaration: Converter Module DCS 400. Online at www.abb.com (accessed
on 2009-05-25).
ABB, 2009b. Environmental Product Declaration: Synchronact 5, Synchronizing and Paralleling Equipment and
System. Online at www.abb.com (accessed on 2009-05-25).
ABB, 2009c. ABB DC drive: DCS800-A, 18 A to 9800/19600 A, Enclosed converters. Online at www.abb.com
(accessed on 2009-05-25).
ABB, 2009d. Environmental Product Declaration for AC-generator type AMG 0900 5125 kVA power. Online at
www.abb.com (accessed on 2009-05-25).
Akiba, S. and S. Yamamoto, 1998. WDM Undersea Cable Network Technology for 100 Gb/s and Beyond. Optical
Fiber Technology. Vol. 4, pp.19-33 (1998). Article No. OF970236.
Alcatel, 1998. Submarine Power Feed Equipment (PFE). Product specification. Online at http://www1.alcatellucent.com (accessed on 2009-05-25).
Alcatel, 2009. How Does It Work? Network architecture. Online at http://www1.alcatellucent.com/submarine/how/index.htm (accessed on 2009-08-18).
Amano, K. and Y. Iwamoto, 1990. Optical Fiber Submarine Cable Systems. Journal of Lightwave Technology, Vol.8, No.
4, pp.595-609, April 1990.
André, M. and N. Brochier, 2007. Overview of Submarine System Upgrades. Paper presented at the submarine cable
conference “SubOptic 2007”, Baltimore, USA.
Arnaiz, S., B. in ’t Groen, C. Rivera, S. Sander, G. Caldeira, N. Vaz, I. Arroyo, S. HeBe and J. Horstink, 2008. Optical
Fibre Cable Recycling at the L-FIRE European Project. Electronics Goes Green 2008+, Merging Technology and
Sustainable Development. Stuttgart: Fraunhofer IRB Verlag. ISBN 978-3-8167-7668-0.
Ayres, R.U., 1995. Life cycle analysis: A critique. Journal of Resources, Conservation and Recycling, Vol.14, p199-223.
Barattino, W. and N. Koopalethes, 2007. The emergence of affordable broadband services for remote locations
using sfoc technology. Paper presented at the submarine cable conference “SubOptic 2007”, Baltimore, USA.
Bare, J.C. and T.P. Gloria, 2006. Critical Analysis of the Mathematical Relationships and Comprehensiveness of Life
Cycle Assessment Approaches. Environmental Science and Technology, Vol.40, No.4, pp.11041113.Baumann, H. and A.-M. Tillman, 2004. The Hitch Hiker’s Guide to LCA. Studentlitteratur: Lund,
Sweden. ISBN: 91-44-02364-2.
Beaufils, J.M., 2000. How Do Submarine Networks Web the World? Optical Fiber Technology. Vol.6, pp.15-32.
Bergelin, F., 2008. Life cycle assessment of a mobile phone, a model on manufacturing, using and recycling. Master
thesis, Ericsson Research and Uppsala Universitet. ISSN: 1401-5773, UPTEC Q08 014.
Betts, P., 2009. Personal communication between 2009-03 and 2009-08 with Mr Betts of Global Crossing Ltd,
London, England. www.globalcrossing.com.
BlueScope, 2009. Energy use in BlueScope Steel’s steelmaking. Online at www.bluescopesteel.com (accessed on
2009-07-02).
BRE, 2005. Green Guide to Specification, BRE Materials Industry Briefing Note 3a: Characterisation. Building
Research Establishment Ltd. Online at www.bre.co.uk (accessed on 2009-07-17).
Breverman, C., G. Valvo and B. Jander, 2007. A new generation of submarine line terminal equipment. Paper
presented at the submarine cable conference “SubOptic 2007”, Baltimore, USA.
CARB, 2008. Emissions Estimation Methodology for Ocean-Going Vessels. Planning and Technical Support
Division, California Air Resources Board (CARB).
Chalmers, 2009. SPINE LCI dataset. Production of paint, thinner and enamel mainly for surface treatment of steel.
Chalmers University, Göteborg, Sweden. Online at
http://www.cpm.chalmers.se/CPMDatabase/Scripts/sheet.asp?ActId=1997-07-10828#Flow%20Data
(accessed on 2009-07-17)
Ciroth, A. and H. Becker, 2006. Validation – The Missing Link in Life Cycle Assessment. Towards pragmatic LCAs.
International Journal of LCA, Issue 11, Vol. 5, pp.295 – 297, 2006. doi:
http://dx.doi.org/10.1065/lca2006.09.271.
Cisco, 2008. Approaching the Zettabyte Era. A White Paper by Cisco Systems, Inc.
Cooper, D. and T. Gustafsson, 2004. Methodology for calculating emissions from ships: 1. Update of emissions
factors. Report series for SMED and MSMED&SLU. Norrköping: SMHI Swedish Metrological and
Hydrological Institute.
Corbett, J.J., 2004. Verification of ship emission estimates with monitoring measurements to improve inventory and
modelling, final report. Prepared for the California Air Resources Board (CARB) and the California
Environmental Protection Agency (CEPA). 23 November 2004.
101
14. References
A life cycle assessment of fibre optic submarine cable systems
Corbett, J.J. and P. Fischbeck, 1997. Emissions from Ships. Science, New Series, Vol.278.No.5339 (Oct.31.1997),
pp.823-824.
Corbett, J.J. and H.W. Koehler, 2003. Updated emissions from ocean shipping. Journal of Geophysical Research, Vol.
108, No. D20, 4650, doi:10.1029/2003JD003751.
Corbett, J. and J. Winebrake, 2007. Sustainable Goods Movement, Environmental Implications of Trucks, Trains,
Ships, and Planes. EM Magazine, Air & Waste Management Association, November 2007, pp.8-12.
Corning, 2008. Fiber 101, Selected Concepts, May 2008. Corning Incorporated. Online at
www.corning.com/opticalfiber/ (accessed on 2009-04-11).
Corus, 2007. Sustainable Steel: Key environmental messages for steel & metal packaging. Online at
www.corusgroup.com (accessed on 2009-07-06).
CPNI, 2006. An overview of the use of submarine cable technology by UK PLC. Report for the Centre for the
Protection of National Infrastructure (CPNI), United Kingdom, March 2006.
Davis, J.R., 2001. Copper and copper alloys. ASM International. ISBN 0871707268.
Dodbiba G., K. Takahashi, J. Sadaki and T. Fujita, 2008. The recycling of plastic wastes from discarded TV sets:
comparing energy recovery with mechanical recycling in the context of life cycle assessment. Journal of Cleaner
Production, Vol.16 (2008), pp.458-470.EAA, 2007. Aluminium Recycling in LCA. July 2007. European
Aluminium Association.
EEA, 1997. Life Cycle Assessment (LCA), A guide to approached, experiences and information sources.
Environmental Issues Series no.6. European Environment Agency (EEA).
Ellingsen, H., A.M. Fet and S. Aanondsen, 2002. Tool for Environmental Efficient Ship Design. ENSUS 2002,
Newcastle, UK, December 16.2002.
European Commission, 2002. Quantification of emissions from ships associated with ship movements between
ports in the European Community. Final Report, July 2002. Prepared by Entec UK Limited.
European Commission, 2007. Impact Assessment. Commission Staff Working Document. Accompanying document
to the Proposal from the Commission to the European Parliament and Council for the regulation to reduce
CO2 emissions from passenger cars. Commission of the European Communities. {SEC(2007)1724}.
Eyring, V., J.J. Corbett, D.S. Lee and J.J. Winebrake, 2007. Brief summary of the impact of ship emissions on
atmospheric composition, climate, and human health. Document submitted to the Health and Environment
sub-group of the International Maritime Organization on 6 November 2007.
Fet, A.M., J. Embelmsvåg and J. Johannese, 1996. Environmental Impacts and Activity Based Costing during
operation of a Platform Supply Vessel. A report for Farstad Shipping ASA, Ålesund, Norway.
Fet, A.M., Michelsen and T. Johnsen, 2000. Environmental performance of transportation - a comparative study.
Report nr 3/2000. Prepared for the Research Council of Norway, by Norwegian University of Science and
Technology (NTNU).
Fet, A.M., 2003. Sustainability reporting in shipping. Journal of Marine Design and Operations, No.B5 2003, pp.11-24.
Fet, A.M., 2009. ISO 14000 as a Strategic Tool for Shipping and Shipbuilding. Online at www.ntnu.no/iot (accessed
on 2009-03-24).
Fullenbaum, M., 2004. State of the art unrepeatered cable: how advanced fibres and packaging have paved the way to
advanced systems. Optical Networks Division, Alcatel Submarine Networks. Paper presented at the
submarine cable conference “SubOptic 2004”, Monaco.
Giurco, D., M. Stewart, T. Suljada and J. Petrie, 2006. Copper recycling alternatives: An environmental analysis.
Department of Chemical Engineering, University of Sydney, NSW, 2006, Australia. 5th Annual
Environmental Engineering Research Event, 20–23 October 2006, Noosa, QLD.
GMSL, 2009. Fleet. Global Marine Systems Ltd, United Kingdom. Online at www.globalmarinesytems.co.uk
(accessed on 2009-03-23).Gnauck, A.H. and A.R. Chraplyvy, 2008. High-Capacity Optical Transmission
Systems. Journal of Lightwave Technology, Vol.26, No.9, pp.1032-1045 (2008).
Graedel, T.E., D. Vanbeers, M. Bertram, K. Fuse, R.B. Gordon, A. Gritsinin, A. Kapur, R.J. Klee, R.J. Lifset,
L.Memon, H. Rechberger, S. Spatari, and D. Vexler, 2004. Multilevel Cycle of Anthropogenic Copper.
Environmental Science & Technology, Vol.38, No.4, pp.1242-1252.
Green, J.A.S., 2007. Aluminium Recycling and Processing for Energy Conservation and Sustainability. ASM International. ISBN
0871708590.
Guggemos, A.A. and A. Horvath, 2005. Comparison of Environmental Effects of Steel- and Concrete-Framed
Buildings. Journal of infrastructure Systems, June 2005, pp93-101.
Guinée, J.B. (final ed), M. Gorrée, R. Heijungs, G. Huppes, R. Kleijn, A. de Koning, L. van Oers, A. W. Sleeswijk, S.
Suh, H. Udo de Haes, H. de Bruijn, R. van Duin, M.A.J. Huijbregts, E. Lindeijer, A.A.H. Roorda, B.L. van
der Ven and B.P. Weidema, 2004. Handbook on Life Cycle Assessment. Operational Guide to the ISO Standards.
Dordrecht: Kluwer Academic Publishers.
Harasawa, S., Sumitani and K. Ohta, 2008. Reliability Technology for Submarine Repeaters. Fujitsu Science Technology
Journal, Vol.44, No.2, pp.148-155 (2008).
Herron, J.K., J. Porto, J. De la Cruz, S. Drew and J. Grant. 2007. The metamorphosis of marine maintenance
providers: meeting the expanding needs of cable system owners. Paper presented at the submarine cable
conference “SubOptic 2007”, Baltimore, Maryland, USA.
102
14. References
A life cycle assessment of fibre optic submarine cable systems
Hilt, J., 2009. The Benefits of Submarine Cables over Satellite Networks. Presentation by Hibernia Atlantic. Online
at www.hiberniaatlantic.com (accessed on 2009-03-24).
Hunkeler, D. and G. Rebitzer, 2005. The Future of Life Cycle Assessment. International Journal of LCA, Issue 10, Vol.
5, pp.305–308, 2006. doi: http://dx.doi.org/10.1065/lca2005.09.001.
Igarashi, Y., I. Daigo, Y. Matsuno and Y. Adachi, 2007. Dynamic Materials Flow Analysis for Stainless Steels in
Japan – Reductions Potential of CO2 Emissions by Promoting Closed Loop Recycling of Stainless Steel. ISIJ
International, Vol.47, No.5, pp.758-763 (2007).
Ishida, K., K. Shimizu, S. Mitani, J. Abe, T. Tokura and T. Mizuochi, 2007. RZ-DQPSK transponder for 40 gbps
submarine cable systems. Mitsubishi Electric Corporation, Japan. Paper presented at the submarine cable
conference “SubOptic 2007”, Baltimore, Maryland, USA.
ISO 14040:2006. Environmental Management – Life cycle assessment – Principles and framework (SS-EN ISO 14040:2006).
Swedish Standards Institute (SIS förlag AB): Stockholm, Sweden.
ISO 14044:2006. Environmental Management – Life cycle assessment – Requirements and guidelines (SS-EN ISO 14044:2006).
Swedish Standards Institute (SIS förlag AB): Stockholm, Sweden.
Jones, A.T., 2009. Electric Arc Furnace Steelmaking. American Iron and Steel Institute. Online at www.steel.org
(accessed on 2009-07-06).
Jönsson, Å., T. Björklund, A.M. Tillman, 1998. LCA Case Studies: LCA of Concrete and Steel Building Frames.
International Journal of LCA, Issue 3, Vol.4, pp216-224, 1998.
Kidorf, H., 2006. Submarine systems supply market rebounds. Lightwave Magazine, 1st November 2006. Online at
www.pioneerconsulting.com (accessed on 2009-07-15).
Kordahi, M., S. Shapiro and G. Lucas, 2007. Trends in submarine cable systems. Paper presented at the submarine
cable conference “SubOptic 2007”, Baltimore, USA.
Lack, D.A, J.J. Corbett, T. Onasch, B. Lerner, P. Massoli, P.K. Quinn, T.S. Bates, D.S. Covert, D. Coffman, B.
Sierau, S. Herndon, J. Allan, T. Baynard, E. Lovejoy, A.R. Ravishankara and E. Williams, 2009. Particulate
emissions from commercial shipping: Chemical, physical, and optical properties. Journal Of Geophysical Research,
Vol. 114, D00F04, pp1-16, doi:10.1029/2008JD011300, 2009.
Lecroart, A., N. Shaheen and P. Shawyer, 2007. Cabled science observatories solutions: bringing power and
broadband communication to the ocean depths. Paper presented at the submarine cable conference
“SubOptic 2007”, Baltimore, Maryland, USA.
Letellier, V., 2004. Submarine systems, from laboratory to seabed. Optics & Photonics News. Optical Society of
America. February 2004.
Lifset, R.J., R.B. Gordon, T.E. Graedel, S. Spatari, and M. Bertram, 2002. Where Has All the Copper Gone: The
Stocks and Flows Project, Part 1. JOM, Vol.54, No.10, pp.21-26.
Lingg, B. and S. Villiger, 2002. Energy and Cost Assessment of a High Speed Ferry. Master thesis, Royal Institute of
Technology (KTH), Stockholm and Swiss Federal Institute of Technology (ETH) Zürich.
Louw, A., 2009. Personal communication between 2009-03-10 and 2009-07-13 with Mr Louw of Mertech Marine,
South Africa. www.mertechmaine.co.za.Markow, 2009. Summary of Undersea Fiber Optic Network
Technology and Systems. Terremark Inc. Presentation.
McGrath, M., 2009. Meeting with Mr McGrath of Telecom New Zealand at Cable Terminal Station, Takapuna, New
Zealand on 2009-02-27. www.telecom.co.nz.
Merret, J. and R. Laude, 2007. Re-use and re-routing of retiring systems. Alcatel Submarine Networks UK Ltd,
London, UK. Paper presented at the submarine cable conference “SubOptic 2007”, Baltimore, Maryland,
USA.
Mertech, 2009. Company Information. Mertech Marine. Online at www.mertechmarine.co.za (accessed on 2009-0713).
NEC, 2008. NEC’s Submarine Cable System. Presentation by Masamichi Imai, December 5, 2008, Broadband
Network Operations Unit, NEC Corporation. Online at www.chotline.net/docs/html/NECC8446/dl/necc081205e_1.pdf (accessed on 2009-03-24).
Oikawa, H., J. Yoshimura and H. Watanabe, 2006. High-Performance Submarine Line terminal Equipment for NextGeneration Optical Submarine Cable System: FLASHWAVE S680. Fujitsu Science Technology Journal,
Vol.42, No.4, pp.469-475 (2006).
PE & LBP, 2008. GaBi Manual, Introduction to GaBi 4. Software-System and Databases for Life Cycle Engineering.
PE International and the Chair of Building Physics, University of Stuttgart.
PE & LBP, 2009. GaBi software database plan. Taken from example database.
Poole, R., 2009. Personal communication on 2009-04-23 with Mr Poole of Earth Sciences and Surveying (EGS).
www.egssurvey.com.
Pre, 2000. The Eco-indicator 99. A damage oriented method for Life Cycle Impact Assessment. Manual for
Designers, 17 April 2000, Second edition. PRé Consultants B.V.
Ridder, J., 2007. Aspects of submarine cable retirement. Deutstche Telecom AG Competence Centre Submarine
Cables. Paper presented at the submarine cable conference “SubOptic 2007”, Baltimore, Maryland, USA.
103
14. References
A life cycle assessment of fibre optic submarine cable systems
Ruddy, M., 2006. An Overview of International Submarine Cable Markets. Presentation by Terabit Consulting for
the Executive Telecoms Briefings, Boston University, December 12, 2006. Online at
www.terabitconsulting.com (accessed on 2009-07-15).
Salomone, R., F. Mondello, F. Lanuzza and G. Micali, 2005. ENVIRONMENTAL ASSESSMENT: An Eco-balance
of a Recycling Plant for Spent Lead–Acid Batteries. Environmental Management Vol.35, No.2, pp.206–219. DOI:
10.1007/s00267-003-0099-x.
Schmitz, C., J. Domagala and P. Haag, 2006. Handbook of aluminium recycling: fundamentals, mechanical preparation,
metallurgical processing, plant design. Vulkan-Verlag GmbH.
Sleeswijk, A., L. van Oers, J. Guinée, J. Struijs, M. Huijbregts, 2008. Normalisation in product life cycle assessment:
An LCA of the global and European economic systems in the year 2000. Science Of The Total Environment,
Vol.390, pp.227–240 (2008). Doi:10.1016/j.scitotenv.2007.09.040.
Spatari, S., M. Betz, H. Florin, M. Baitz and M. Faltenbacher, 2001. Using GaBi 3 to Perform Life Cycle Engineering.
International Journal of LCA, Issue 6, Vol.2, pp.81-84, 2001.
Spatari, S., M. Bertram, R.B. Gordon, K. Henderson and T.E. Graedel, 2005. Twentieth century copper stocks and
flows in North America: A dynamic analysis. Ecological Economics, Vol.54 (2005), pp.37–51.
Steel Recycling Institute, 2007. The Inherent Recycled Content of Today’s Steel. Report by the Steel Recycling
Institute. Online at www.recycle-steel.org (accessed on 2009-07-02).
Städje, J., 2009. Sunet först med 40 Gbps under Atlanten. Report for web magazine Teknik360. Online at
http://t360.idg.se/2.8229/1.216279/sunet-forst-med-40-gbps-under-atlanten (accessed on 2009-03-06).
Suyama, M., M. Nagayama, H. Watanebe, H. Fujiwara and C. Anderson, 1999. WDM Optical Submarine Network
Systems. Fujitsu Science Technology Journal, Vol.35, No.1, pp.34-45 (1999).
Telegeography, 2009. Global bandwidth forecast Service: Methodology. Telegeography Research, PriMetrica Inc:
Washington, D.C., USA.
Todd, K., 2009. Personal communication on 2009-04-08 with Mr Todd of Global Marine Systems Ltd, Chelmsford,
England. www.globalmarinesystems.co.uk
Trischitta, P.R., A.J.C. Medina and R.C. Remedi, 1997. The Pan American Cable System. IEEE Communications
Magazine, December 1997.
UN, 2009. World Population Prospects: The 2008 Revision, Population Database. Population Division of the
Department of Economic and Social Affairs of the United Nations. Online at
http://esa.un.org/unpp/p2k0data.asp (accessed on 2009-08-19).
USEPA, 2006. Life Cycle Assessment: Principles and Practice. Report prepared by Scientific Applications
International Corporation (SAIC), for National Risk Management Research Laboratory, US Environmental
Protection Agency, EPA/600/R-06/060, May 2006.
Veverka, D., 2009. Personal communication between 2009-03 and 2009-09 with Mr Veverka of Southern Cross
Cables Ltd, New Zealand. www.southerncrosscables.com.
Viking and Österberg, 2004. Thesis work in Regional Planning. Department of Urban Studies, The Royal Institute of
Technology (KTH), Stockholm, Sweden.
Willey C., P.J. Footman Williams, P. Rego, J. de la Cruz, 2007. Re-installation of recovered submarine cables; case
histories of success. Tyco Telecommunications (US) Inc. Paper presented at the submarine cable conference
“SubOptic 2007”, Baltimore, Maryland, USA.
Williams, E. and Y. Sasaki, 2003. Energy Analysis of End-of-life Options for Personal Computers: Resell, Upgrade,
Recycle.
World Steel, 2008. Fact Sheet: Energy, Steel and Energy. World Steel Association. Online at www.worldsteel.org
(accessed on 2009-07-06).
14.2.
Internal Ericsson References
3GLCA, 2002. Life cycle assessment of a 3G system (Final report). Document No: 9/0363-FCP1032560.
Berggren, 2009. Personal communication on 2009-04-21&22 with Mr Berggren of Ericsson Network Technologies,
Hudiksvall, Sweden.
Characteristics Specs, 2009. System Characteristics; EDA 1200 4.2. Document No: 155 02-FGC 101 0316/3 Uen.
Malmodin, 2009. Personal communication with Mr Malmodin of Ericsson Research, Kista, Sweden.
MECH, 2001. Mechanics manufacturing processes. Document No: 5/1551-FDP 103 2560 Uen.
Jonsson, 2009a. M. Sc. Thesis: LCA on Submarine Opto-Cable. Document No: EAB-09:002628.
Jonsson, 2009b. Telepresence - Comparing Bit and Air Travel. Document No: EAB-08:082380.
Norlund, 2009. Personal communication on 2009-04-23 with Mr Norlund of Ericsson Network Technologies,
Hudiksvall, Sweden.
PBA, 2001. RBS PBA Assembly and RBS Final Assembly. Document No: 7/1551-FCP 103 2560 Uen.
Pb-Battery, 2001. Lead acid battery, manufacturing process. Document No: 8/1551-FCP 103 2560 Uen
Jonsson, 2009. Telepresence - Comparing Bit and Air Travel. Document No: EAB-08:082380.
104
15. Appendices
A life cycle assessment of fibre optic submarine cable systems
15.Appendices
15.1.
Appendix A – Calculation of the Generic Cable System
Adapted from Ruddy, 2006
Cable capacity - Year end 2006
Cable Name
Transatlantic
Columbus-2
CANTAT-3
TAT-12/TAT-13
Atlantic Crossing-1 (AC-1)
Columbus-3
Yellow (Level-3) / Atlantic
Crossing-2 (AC-2)
Hibernia Atlantic
FLAG Atlantic-1 (FA-1)
TAT-14
VSNL Transatlantic (Tyco)
Apollo
Total: 11 Systems, 22% lit
Transpacific
TPC-5
Pacific Crossing-1 (PC-1)
China-US Cable Network
Japan-US Cable Network
VSNL Transpacific (Tyco)
Total: 5 systems, 14,6% lit
South Asia
Sea-Me-We-2
FLAG (Fiberoptic Link Around
the Globe)
Sea-Me-We-3
i2i (ISCN)
SAT-3/WASC/SAFE (South
Atlantic-3/West Africa
Tata Indicom ChennaiSingapore (TICSCS)
Sea-Me-We-4
Falcon
Total: 8 systems, 5,3% lit
Total
Ready
for
Service
Date
Route
Length km
Lit
Capacity
(Gbps)
Design
Capacity,
Est. (Gbps)
Lit Capacity
as % of
design
Landings
1994
1994
1995
1998
1999
12188
7500
12553
14000
10000
2
5
30
140
20
2
5
30
140
40
100%
100%
100%
100%
50%
6
6
5
4
5
2000
2001
2001
2001
2001
2003
6960
11700
12800
15000
12500
13000
128201
320
220
530
640
480
320
2707
1280
1920
2400
640
2560
3200
12217
25%
11%
22%
100%
19%
10%
22.16%
2
4
4
7
2
4
49
1995
1999
2000
2001
2002
22560
13076
30800
21000
24100
111536
20
180
80
400
640
1320
20
640
80
640
7680
9060
100%
28%
100%
62%
8%
14.57%
6
4
9
6
5
30
1994
18000
1
1
100%
15
1997
1999
2002
27763
39000
3200
10
58
160
20
80
8400
50%
72%
2%
17
39
2
2002
27850
30
120
25%
17
2004
2006
2006
3100
20000
10300
149213
320
160
90
829
3175
1280
2560
15636
10%
13%
4%
5.30%
2
17
16
125
Systems
24
Length
388950
Lit
4856
Design
36913
Lit vs Design
13.16%
Landings
204
Average System
Normalised to 10000km of cable
Route
Length km
16206
10000
Lit
Capacity
(Gbps)
202
Notes:
Lit capacity: current installed capacity
Design capacity: Limits to upgrading process
Bandwidth usage: Actual usage of cable
105
Design
Capacity.
Est. (Gbps)
1538
Lit Capacity
as % of
design
13.16%
Landings
8.5
5.2
Lit
Capacity
used for
Study
(Gbps)
320
220
530
640
480
320
400
640
160
320
160
Lit
Capacity
used for
Study
(Gbps)
381
381
15. Appendices
15.2.
No.
A life cycle assessment of fibre optic submarine cable systems
Appendix B – Data Sources
Process
Nation
Data Source
Data Provider
Year
1
Acrylonitrile-butadiene-styrene (ABS) in municipal waste incinerator
RER
ELCD/PE-GaBi
PE-GaBi 2006
2005
2
Acrylonitrile-butadiene-styrene granulate (ABS)
RER
ELCD/PlasticsEurope
PE-GaBi 2006
2005
3
Aluminium die-cast part
DE
PE
PE-GaBi 2006
2005
4
Aluminum ingot
RER
BUWAL
PE-GaBi 2006
1996
5
Argon (gaseous)
DE
PE
PE-GaBi 2006
2005
6
Bitumen at refinery
EU-15
PE
PE-GaBi 2006
2003
7
Brass
DE
PE
PE-GaBi 2006
2002
8
Cable waste in municipal waste incinerator
RER
PE
9
Cast iron part (sand casting)
DE
PE
PE-GaBi 2006
2005
10
Commercial waste in municipal waste incinerator
RER
PE
PE-GaBi 2006
2005
11
Copper mix (99,999% from electrolysis)
DE
PE
PE-GaBi 2006
2002
12
Corrugated cardboard
CH
BUWAL
PE-GaBi 2006
1996
13
Diesel at refinery
EU-15
ELCD/PE-GaBi
2003
14
Enamel paint and thinner for steel
15
Epoxy resin
RER
PlasticsEurope
PE-GaBi 2006
Chalmers
University
PE-GaBi 2006
16
Fuel oil heavy at refinery
EU-15
ELCD/PE-GaBi
2003
17
Fuel oil heavy at refinery
US
PE
2003
18
Fuel oil light at refinery
EU-15
ELCD/PE-GaBi
19
Glass (white; packaging)
CH
BUWAL
PE-GaBi 2006
1996
20
Glass fibres
DE
PE
PE-GaBi 2006
2005
21
DE
PE
PE-GaBi 2006
2005
RER
PE
PE-GaBi 2006
2005
23
Hexamethylenediamine (HMDA; via Adipic acid)
Landfill (Commercial waste for municipal disposal; AT, DE, IT, LU, NL, SE,
CH)
Lead (99,995%)
DE
PE
PE-GaBi 2006
2000
24
Limestone hydrate (Ca(OH)2)
DE
PE
PE-GaBi 2006
2000
25
Natural gas mix
26
Nitrogen (gaseous)
PE-GaBi 2006
2005
27
Oxygen (gaseous)
DE
PE
PE-GaBi 2006
2005
28
Paper / Cardboard in municipal waste incinerator
RER
ELCD/PE-GaBi
PE-GaBi 2006
2005
29
Paper woody uncoated
CH
BUWAL
PE-GaBi 2006
1996
30
Polycarbonate granulate (PC)
RER
ELCD/PlasticsEurope
PE-GaBi 2006
2005
31
Polyester resin (UP; unsaturated)
32
Polyethylene (PE) in municipal waste incinerator
RER
ELCD/PE-GaBi
PE-GaBi 2006
2005
33
Polyethylene high density granulate (PE-HD)
RER
ELCD/PlasticsEurope
PE-GaBi 2006
2005
34
RER
PlasticsEurope
PE-GaBi 2006
2005
RER
PE
PE-GaBi 2006
2005
36
Polypropylene film (extended) (PP)
Populated printed wiring board (before RoHS), in municipal waste
incinerator
Propene (propylene)
RER
PlasticsEurope
PE-GaBi 2006
2005
37
Silica sand (flour)
DE
PE
PE-GaBi 2006
2005
38
Silicon mix (99%)
DE
PE
PE-GaBi 2006
2000
39
Sodium hydroxide (100%; caustic soda)
RER
ELCD/PlasticsEurope
PE-GaBi 2006
2005
22
35
2005
PE
2002
PE
106
2005
2003
ELCD/PE-GaBi
DE
1997
2005
15. Appendices
No.
Process
40
A life cycle assessment of fibre optic submarine cable systems
Nation
Data Source
Data Provider
Year
Stainless steel cold roll
DE
PE
PE-GaBi 2006
2004
41
Steel billet
DE
PE
PE-GaBi 2006
2004
42
Steel cast part alloyed
DE
PE
PE-GaBi 2006
2005
43
Steel cold rolled
DE
PE
PE-GaBi 2006
2004
44
Steel sheet 1.5mm el. zinc plated (0.01mm; 1s)
DE
PE
PE-GaBi 2006
2004
45
Styrene
RER
PlasticsEurope
PE-GaBi 2006
2005
46
Styrene-butadiene rubber mix (SBR)
DE
PE
2005
47
subsea.Average CABLE ship MANOEUVRING (24hrs)
48
subsea.Average CABLE ship PORT (24hr)
49
subsea.Average CABLE ship TRANSIT (24hrs)
50
subsea.Average RESEARCH ship MANOEUVRING (24hrs)
51
subsea.Average RESEARCH ship PORT (24hrs)
52
Sulphuric acid (96%)
PE
PE-GaBi 2006
Cooper and
Gustafsson
Cooper and
Gustafsson
Cooper and
Gustafsson
Cooper and
Gustafsson
Cooper and
Gustafsson
PE-GaBi 2006
53
Thermal energy from gas
BUWAL
PE-GaBi 2006
1996
54
Thermal energy from heavy fuel oil
EU-25
ELCD/PE-GaBi
PE-GaBi 2006
2002
55
Thermal energy from natural gas
EU-25
ELCD/PE-GaBi
PE-GaBi 2006
2002
56
DE
BUWAL
PE-GaBi 2006
1996
GLO
PE
PE-GaBi 2006
2005
58
Tin plate
Truck-trailer > 34 - 40 t total cap./ 27 t payload / Euro 3 (Truck fleet, longdist.)
Truck-trailer up to 28 t total cap. / 12,4 t payload / Euro 4
GLO
PE
PE-GaBi 2006
2005
59
x Air travel
Bergelin
2008
60
x Dismantling electronic scrap (for processes)
Bergelin
2008
61
x Electricity (China av.)
Bergelin
2008
62
x Gold production
Bergelin
2008
63
x Hazardous waste treatment
Bergelin
2008
64
x Kaldo furnace for processes
Bergelin
2008
65
x Nickel production
Bergelin
2008
66
x Schredding electronic scrap (for processes)
Bergelin
2008
67
xH450: Standard components model[2]
Ericsson
2002
68
xM240: RBS PBA process
Ericsson
2002
69
xM330: PCB manufacturing
Ericsson
2002
70
xM332: PCB materials[2]
Ericsson
2002
71
xM401: Connectors
Ericsson
2002
72
xM531: IC chip class-A manufact. part II (Copy)
Ericsson
2002
73
xM532: IC chip class-B manufact. part II
Ericsson
2002
74
xP012: Electricity (EU av.) v
EU
Ericsson
2002
75
xP014: Electricity (US av.) v
US
Ericsson
2002
76
xP015: Electricity (Japan av.) v
JA
Ericsson
2002
77
xX007: Silver[2]
Bergelin
2008
78
Zinc redistilled mix
PE-GaBi 2006
2002
57
RER
CN
GLO
AG
DE
107
PE
2004
2004
2004
2004
2004
2005
15. Appendices
15.3.
A life cycle assessment of fibre optic submarine cable systems
Appendix C – Stakeholder Analysis
Company
Link to submarine cables
Location
Alcatel
System manufacture, installation and maintenance
England, France
British Telecom
Cable Owner
United Kingdom
Corning Incorporated
Optical fibre manufacture
USA
EGS
Cable route survey
Hong Kong
Ericsson Cables
Cable manufacture
Sweden
Fujitsu
Repeater manufacture
Japan
Global Crossing
Cable owner
Global offices
Global Marine Systems Ltd
Cable installation and maintenance
England
ICPC
International Cable Protection Committee
Global
Mertech Marine
Cable recovery
South Africa
NEC
Cable and repeater manufacture
Japan
Southern Cross Cable Network
Cable owner
Global offices
Sumi Electric
Corning Incorporated
Japan
Sumitomo
Cable manufacture
Japan
Telecom New Zealand
Cable operator
New Zealand
Telegeography
Research and monitoring of submarine systems
USA
Telia
Cable owner
Sweden
Tyco
System manufacture, installation and maintenance
USA
108
15. Appendices
15.4.
A life cycle assessment of fibre optic submarine cable systems
Appendix D – Detailed System Flowchart of GaBi software sub-model
109
15. Appendices
15.5.
A life cycle assessment of fibre optic submarine cable systems
Appendix E – Questionnaire to Suppliers
Craig Donovan
Master’s Thesis
Stockholm
Sweden
Dear Sir/Madam,
Re: Data collection - Life Cycle Assessment (LCA) of submarine cables
I am a student undertaking my Master of Science at the Royal Institute of Technology (KTH) in Stockholm,
Sweden. The field of study is Environmental Engineering and Sustainable Infrastructure. Background to the
course
can
be
found
at
(http://www.kth.se/studies/master/programmes/be/2.1572?l=en).
I have recently commenced my thesis project in conjunction with KTH and Ericsson Research in Stockholm, in
the area of Life Cycle Assessment (LCA) of submarine fibre optic cables. The research
encompasses assessment of the environmental impact (for example CO2 emissions) of submarine cables from
cradle to grave, or, from raw material extraction to decommissioning.
These cables support our voice and data communications in an extremely efficient manner, yet little is known
about the impact of these cables from an LCA perspective. We have undertaken some preliminary investigation
and a study of this kind does not appear to have been completed. Therefore, I hope that this study can be of
benefit to the submarine cable industry as a whole.
The process of building an LCA model requires accounting for the inputs - raw material and energy, and the
outputs - emissions and waste, of the studied system. In this case information relating to the production of optical
fibre, plastics, steel and other materials used in the production of submarine cables systems.
As a supplier of raw materials to Ericsson Cables, the data you could provide would greatly help my research
and facilitate the building of a complete life cycle model.
110
15. Appendices
A life cycle assessment of fibre optic submarine cable systems
Questions to suppliers:
a.
Do you have any personnel working with LCA and has an LCA study been undertaken for the
product?
b.
What are the raw materials that go into making the product?
c.
How far are the raw materials transported to your processing factory?
d.
By what method are they transported? The approximate gross tonnage of the ship/train/truck?
e.
How much energy does it take to produce X amount of final product, ready for supply to
Ericsson Cables?
f.
What is the source of that energy (For example: electricity from coal)?
g.
How much waste is produced in this process and that can be attributed to the product?
h.
What percentage of that waste is recycled and how much is sent to landfill?
Much of this data would be contained in annual reports, product specification sheets and process specifications.
Confidentiality would be strictly maintained if these resources were made available.
Due to time limitations, it is important that any data be supplied in good time in order to progress the research.
I can be contacted at: [email protected]
Thank you in advance for your support.
Yours faithfully
Craig Donovan
111
15. Appendices
15.6.
A life cycle assessment of fibre optic submarine cable systems
Appendix F – Sensitivity Analysis Results
Terminal Raw
Repeater
Repeater Raw
Materials,
internal
Materials,
Manufacturing
Terminal
electronics at Manufacturing and E-o-L at electricity use
400%
& E-o-L at 0%
0%
at 70%
Cable
maintenance Ship emissions
by ship at
to Marine
150%
Distillate fuel
Lifetime 25
years at
10000Gb.km
relative
No
recovery at
E-o-L
Impact category
Raw transport
at 500%
Recycling
transport at
1000%
Primary Energy
1,6%
3,8%
1,0%
-0,6%
-1,5%
-17,3%
-13,0%
7,5%
0,0%
-12,4%
2,6%
Electricity
0,0%
0,0%
1,1%
-0,5%
-1,4%
-26,8%
0,0%
0,0%
0,0%
-4,1%
-4,1%
Heavy Fuel Oil
0,0%
0,0%
0,0%
-0,1%
0,0%
0,0%
0,0%
26,3%
0,0%
-22,8%
-22,8%
Abiotic Resource
Depletion
2,1%
5,0%
0,9%
-0,6%
-1,4%
-15,0%
-18,8%
9,9%
0,0%
-13,9%
6,5%
Acidification Potential
0,3%
0,8%
0,0%
0,0%
-0,1%
-1,9%
0,9%
24,8%
-46,7%
-21,1%
-18,9%
Freshwater Aquatic
Ecotoxicity Potential
0,1%
0,1%
0,9%
-0,5%
-1,2%
-21,3%
-76,4%
5,2%
-16,9%
-8,1%
-1,2%
Terrestrial Ecotoxicity
Potential
0,2%
0,5%
0,4%
-0,2%
-0,7%
-8,7%
-21,5%
17,8%
-59,5%
-16,7%
-13,2%
Marine Aquatic
Ecotoxicity Potential
0,2%
0,5%
0,6%
-0,4%
-1,0%
-13,9%
65,1%
12,3%
-27,1%
-13,5%
-2,0%
Global Warming
Potential
1,1%
2,6%
0,6%
-0,3%
-0,9%
-9,0%
-7,6%
17,0%
2,1%
-16,9%
-7,7%
Photochemical Ozone
Creation Potential
0,5%
1,3%
0,1%
-0,1%
-0,2%
-1,9%
1,3%
24,5%
-42,7%
-21,4%
-17,1%
Ozone Depletion
Potential
1,7%
4,1%
-1,1%
-15,6%
-19,2%
0,0%
5024,6%
8,9%
0,0%
-39,4%
126,0%
Eutrophication
Potential
0,5%
1,3%
0,1%
-0,1%
-0,3%
-1,8%
-3,5%
24,9%
-21,9%
-21,2%
-19,0%
Human Toxicity
Potential
0,1%
0,2%
0,2%
-0,1%
-0,3%
-5,0%
-13,4%
21,7%
-69,3%
-19,0%
-14,6%
112
EU-25
electricity
production