C-accounting and the role of LCA in waste management
Thomas H Christensen
Technical University of Denmark
ICWMT
Beijing, PR China
October 2016
Introduction
Waste management can be described by three main challenges
Controlling esthetic, hygienic and contamination risks
Recovering resources: materials, energy and elements/nutrients
Socio-economical acceptance
Our managing approaches have over time been named by a range
of concepts and slogans
Waste hierarchy
Cradle-to-grave, cradle-to-cradle
Zero waste
Green technology
Sustainable technology
Circular economy
Today’s presentation: Environmental quantification
3 take-home-messages:
Quantification of climate change impacts: C-accounting
System approach
Move from single value quantification to distributions
Use life-cycle-assessment
modelling (LCA)
Quantification of impacts
C-accounting/climate change
Environmental impacts are many:
Climate Change
Eutrophication (freshwater, marine, terrestrial)
Acidification
Human Toxicity (carcinogenic, non-carcinogenic)
Ecotoxicity
Particulate Matter (air)
Resource Depletion (fossil, abiotic)
Quantification of impacts
C-accounting/climate change
Environmental impacts are many:
Climate Change
Eutrophication (freshwater, marine, terrestrial)
Acidification
Human Toxicity (carcinogenic, non-carcinogenic)
Ecotoxicity
Particulate Matter (air)
Resource Depletion (fossil, abiotic)
In general:
For bulk waste: MSW, demolition waste, agricultural waste etc:
Climate change is important
For specific/hazardous waste: WEEE, shredder waste etc: Toxicity is
important
Quantification of impacts
C-accounting/climate change
For waste
management we
Environmental impacts are many:
cannot directly
Climate Change
use the
Eutrophication (freshwater, marine, terrestrial)
approach of
Acidification
IPCC
Human Toxicity (carcinogenic, non-carcinogenic)
Ecotoxicity
Particulate Matter (air)
Resource Depletion (fossil, abiotic)
In general:
For bulk waste: MSW, demolition waste, agricultural waste etc:
Climate change is important
For specific/hazardous waste. WEEE, shredder waste etc: Toxicity is
important
The waste management system
emissions
emissions
•Mass balances
emissions
Load to the
environment
•Energy budget
•Emission account
materiale
waste
materiale
waste
materiale
waste
energy
materiale
energy
Materiales and
energy can
substitute for
other production
of materials and
energy
Saving to the
environment
emissions
emissions
emissions
The system approach has go beyond the
waste management system
materiale
waste
materiale
waste
materiale
waste
energy
materiale
energy
Materiales and
energy can
substitute for
other production
of materials and
energy
Characterization Factors
C counting as GHG:
Consider changes caused by waste management: Biogenic CO2 is neutral
C-fossil emitted as CO2: GWP = 1 Kg CO2-eqivalents/ kg CO2
C-fossil bound: GWP = 0
C-biogenic emitted as CO2: GWP = 0
C-biogenic bound: - 3.67 Kg CO2-eqivalents/ kg C bound (after 100 years)
avoided C-fossil emitted as CO2: GWP = -1 Kg CO2-eqivalents/kg CO2
avoided C-biogenic emitted as CO2: GWP = 0
release of bound C-biogenic: 3.67 Kg CO2-eqivalents/ kg C released
C emitted as methane: 28 kg CO2-equivalents/ kg CH4 (100 years)
Characterization Factors
C counting as GHG:
Consider changes caused by waste management: Biogenic CO2 is neutral
C-fossil emitted as CO2: GWP = 1 Kg CO2-eqivalents/ kg CO2
C-fossil bound: GWP = 0
C-biogenic emitted as CO2: GWP = 0
C-biogenic bound: - 3.67 Kg CO2-eqivalents/ kg C bound
avoided C-fossil emitted as CO2: GWP = -1 Kg CO2-eqivalents/kg CO2
avoided C-biogenic emitted as CO2: GWP = 0
release of bound C-biogenic: 3.67 Kg CO2-eqivalents/ kg C released
C emitted as methane: 28 kg CO2-equivalents/ kg CH4 (100 years)
Biogenic
C
Mass balance of landfill: 100 years
Depends on
the
degradation
k
Manfredi,S. & Christensen,T.H. (2009):
Environmental assessment of solid waste landfilling
technologies by means of LCA-modeling. Waste
Management, 29, 32-43.
System approach
We need to include the upstream (energy and materials used)
and the downstream (savings by recycling and use of recovered
energy) activities in our quantitative model for GHG accounting
Usually a range of technologies are needed to achieve recovery
of materials, energy and elements/nutrients
Waste is a heterogeneous material and most single technologies
have rejects/residues that need other treatment
A simple system may look like
Plastic recycling: mechanical treatment of
source separated mixed plastic
Mass balance of plastic sorting and recyling
360
Hard plastic
110
Non-re-plastic
260
Total plastic (kg)
Paper
1000
2400
Wood
300
Textile
300
Iron, cans
225
Aluminium
75
Inert (Glass)
Total (kg)
900
5200
-
70%
151 kg
-
20%
43 kg
-
-
51%
28 kg
-
80%
144 kg
31%
17 kg
-
151
-
71
-
161
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
151
71
161
10%
22 kg
20%
36 kg
18%
10 kg
100%
130 kg
198
100%
35 kg
100%
10 kg
100%
10 kg
53%
17 kg
70%
7 kg
100%
70 kg
347
Downcycling
Reject/
fuel
Aluminium
Soft plastic
80%
216 kg
50%
180 kg
50%
55 kg
50%
130 kg
581
1.5%
35 kg
3.3%
10 kg
3.3%
10 kg
14%
32 kg
13%
10 kg
8%
70 kg
748
Iron
270
Plasmix
Bottles, plastic
MRF transfer-coefficients
POF mix
Source
separation
efficiency
PET
kg associated
with 1000 kg
MSW plastic
waste
HDPE
19% Plastic and
others in MSW
plastic
in the
MSW
-
-
-
-
-
-
-
-
-
-
-
-
-
-
47%
15 kg
-
-
-
30%
3 kg
-
15
3
Plastic recycling
Metal
recycling
LCA- modelling is the systematic approach
Example of output in terms of CO2-equi. /ton MSW
Collection and
transport
Global Warming
Paper
recycling
WB
Glass
recycling
20.00
10.00
Metal
recycling
0.00
-10.00
RDF in cement
kiln
Plastic in
cement kiln
mPE/fu
Anaerobic
digestion
-20.00
Incineration
WI-2
WI-3
WI-4
WI-5
WI-6
Incineration
MBT
Plastic recycling
Transport and collection
RDF in cement kiln
Plastic in cement kiln
Anaerobic and/or Aerobic digestion
-30.00
MRF
-40.00
Landfill
-50.00
-60.00
Plastic
recycling
WI-1
Ash utilization (Germany, Norway)
Metal recycling
Glass recycling
-70.00
Paper recycling
-80.00
Total
Alternative uses
Land-use-change
Fodder production
6
Electricity: 1 kWh
kg CO2-eq. per kWh electricity
Food waste and
other bioresidues
for green energy
Coal
Natural gas
4
2
0
0.6
Biomethane: 1 MJ
Gasoline
kg CO2-eq. per MJ input to vehicle
Not single values but intervals/
average plus 95% confidence
Use of a consequential approach
0.4
0.2
0.0
Whey
Beet molasses
Beet pulp
Brewer's grain
Wild grass
Straw
Food waste
Sewage sludge
Chicken manure
Cow manure
Tonini, D. et. 2016
Technical Univ. of Denmark
Pig manure
-0.2
Moving to distributed results
Variation in results can be of different nature
Modeling approach
Scenario setting
Parameter values
One approach:
Parameterize all values and choices in the model
Estimate the distribution of each parameter
Run Monte Carlo simulations
A shortcut for determining uncertainty
Simple
The variation around the average result can be calculated
analytically with Global
calculation
Sensitivity Analysis
For each model parameter:
of
sensitivity
ratio
Uncertainty
= f( Sensitivity
(output)
Depends on the
model
Uncertainty
(input)
*
Uncertainty
(input)
·
*
Depends on the
nature of the
parameter
)
Same as
input to
Important parameters Monte
Carlo!
*
* Uncertainty (output)
Sensitivity
The total scenario uncertainty can be obtained
summing the contribution to uncertainty of each parameter
Few parameters describe the uncertainty
Percentage of represented analytical variance
Identification of
IMPORTANT parameters
Uncertainty output= Σ (Uncertainty priority) + Σ (Uncertainty remaining)
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
0
1
GWP
TA
2
3
4
5
6
7
8
Number of parameters included in the uncertainty propagation
ODP
TE
HTc
FE
HTnc
ME
PM
totET
IR
RDfos
9
10
POFP
RD
Bisinella, V., Conradsen, K., Christensen, T.H., Astrup, T.F. (2016). A global approach for sparse representation of uncertainty in Life Cycle Assessments
of waste management systems. Int. J. Life Cycle Assess. 21, 378–394.
Conclusion
Use LCA to understand your waste management system
It provides a stringent understanding of your system
It provides transparency as to what matters
Use a system approach
Include those parts outside the waste management system
The savings usually take place outside our system, but are still
important
The context defines the system
No single value results in the future –hopefully
Accept that results are uncertain
Provide quantification of uncertainty
Simplified methods are available targeting your data collection
In C-accounting
Use consistent characterization factors also those you do not like
Thank you
fro your
attention