Biobased geological CO2 storage
CO2SolStock
April 2009 - March 2012
Outreach synthesis report
FP7 funded R&D project
Theme Energy Future Emerging Technologies
March 2012
Report authors
Dr. Caroline Zaoui,
Dr. Gauthier Chapelle
& Dr. Pierre-Jean Valayer
Credits
the FP7 European project CO2SOlStock consortium.
Acknowledgement is given to the
following partners who contributed to
the project:
University of Edinburgh (UK,
Coordinator)
Technische Universiteit Delft
(Netherlands)
Dr Bryne Ngwenya
School of GeoSciences
The University of Edinburgh
Grant Institute - The King’s Buildings
West Mains Road
Edinburgh EH9 3JW, Scotland
[email protected]
http://www.geos.ed.ac.uk/homes/
bryne
Prof Mark Van Loosdrecht
Julianalaan 67
2628 BC Delft,
The Netherlands
[email protected]
tnw.tudelft.nl/en/about-faculty/.../
profdrir-mcm-van-loosdrecht/
Universidad de Granada (Spain)
mrivadeneira.pdf
Dr Gauthier Chapelle, Dr Caroline
Zaoui & Dr. Pierre-Jean Valayer
Biomim-Greenloop nv/sa
Aalststraat 7-11 Rue d’Alost
1000 Brussels, Belgium
[email protected]
[email protected]
[email protected]
http://greenloop.eu/about-us
Université de Lausanne
(Switzerland)
Université de Neuchâtel
(Switzerland)
Prof Eric Verrecchia
Faculté des Géosciences et de
L’environnement
Institut de Géologie et Paléontologie IGP
Quartier UNIL-Dorigny
Bâtiment Anthropole 4161
CH - 1015 Lausanne, Switzerland
[email protected]
www.unil.ch/unisciences/ericverrecchia
Prof Pilar Junier
Laboratory of Microbiology
University of Neuchâtel
Rue Emile-Argand 11, Case postale
158
CH-2000 Neuchâtel, Switzerland
[email protected]
http://www2.unine.ch/lamun
Prof Marian Rivadeneyra
Facultad de Ciencias
Campus de FuentenuevVa
18071-Granada, Spain
[email protected]
http://www.institutodelagua.es/
Biomim-Greenloop SA
(Belgium)
Proofreader
Dr. Bryne Ngwenya
Follow-up contact
Biomim-Greenloop SA (Belgium)
Dr Caroline Zaoui & Dr Gauthier
Chapelle
Biomim-Greenloop nv/sa
Aalststraat 7-11 Rue d’Alost - Door C,
3rd Level - 1000 Brussels, Belgium
Phone: +32 (0)2 213 36 70
Cover and layout
Atelier Graphique Numic
[email protected]
You may re-use this publication (not including any departmental or agency logos) free of charge in any format for research, private
study or internal circulation within an organisation. You must re-use it accurately and not use it in a misleading context. The material must be acknowledged as foregrounds of the CO2SolStock consortium, and you must give the title of the source publication.
I. INTRODUCTION
4
I. 1 The climate change context
3
I. 2 The biomimetic approach of CO2SolStock
6
I.3 A “Future Emerging Technology”?
8
I. 4 Carbon Capture & Storage
8
II. CO2SOLSTOCK OBJECTIVES
10
III. CO2SOLSTOCK EVALUATION: A SYNTHETIC VIEW
12
IV. CO2SOLSTOCK PATHWAYS
16
IV. 1 Subsurface systems: Carbon sequestration in a high pressure/
high salinity environment
17
IV. 2 Industrial ecology using desalination brines:
application to wastewater treatment
18
IV. 3 Dual wastewater treatment & silicate rocks
process for carbon sequestration
21
IV. 4 The oxalate-carbonate pathway: turning sunlight into stone
24
V. WHAT WE LEARNED
30
V. 1 Mitigation impact on atmospheric CO2
31
V. 2 What about the ocean?
33
V.3 CCS & CO2SolStock impact on climate change
34
V. 4 Calling for a paradigm shift
35
V. 5 Stakeholders’ responsibility
35
VI. NEXT STEP
36
VI. 1 Paradigm shift innovation opportunities
37
VI. 2 A call to further cooperation
37
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
3
I. INTRODUCTION
4
I.1
The climate change
Climate change linked to intensive fossil
fuels use is increasingly considered as the
most important challenge facing mankind for
this century. The response will be two-fold:
mitigation, to reduce as much as possible
the man-made greenhouse gas emissions,
and adaptation, since important societal
consequences are already unavoidable. In
any case, climate change is a long inertia
phenomenon
action undertaken to tackle it will decrease
its speed.
The main causal factor of climate change and
global warming is the massive injection
of CO2 and other greenhouse gases in
the atmosphere. Today, 40 Gt CO2 /yr are
emitted, mainly from fossil fuels, cement
industry and forest losses. About half of it
is absorbed by the ocean, at the expense of a
human-induced release has increased CO2
concentration from an initial 280 ppmv to
392 ppmv in 2011, a level never recorded
during the last million year (corresponding
to the limit of the ice archives).
Figure 1. Time range of various consequences of CO2 emissions in the course of the millennium,
corresponding to a still hypothetical scenario of drastic reducing of CO2 emissions after 2050.
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
5
I.2
The biomimetic approach of CO2SolStock
CO2SolStock as a project was designed
as a mitigation response: the idea was
to investigate a biomimetic approach
relying on the capacity of microbes to induce
calcium carbonate precipitation for carbon
sequestration, as an alternative to the
Carbon Capture & Storage (CCS) already in
development. The various processes would
then take CO2 as a gas out of the atmosphere
to transform it into a solid form, namely as a
mineral.
In contrast with the CCS approach,
CO2SolStock initiator’s wish was to be
inspired by the way living organisms do store
CO2 and regulate its concentration in the
atmosphere. Within the possibilities offered
2), it is the microbial carbonatation
pathway that was selected as a model.
BIOMIMETIC POTENTIAL
CARBON SEQUESTRATION
Photosynthesis
Limestone
precipitation
Picture credit: [email protected]
Plankton
Plankton
Bacteria...
Mollusks
...with trees
& fungi
...alone
Picture credit: Paul J. Morris
formation as shells (various planktonic organisms & mollusks) or as deposits that can become rocks.
6
Carbon cycle & reservoirs
Within the global carbon cycle, reservoirs are very
variable in size. For example, the ocean contains 50
times more carbon than the atmosphere. Most notably,
carbonatation, for which microbial activity is an important
actor, has accumulated over the eons a huge carbonate
rock reservoir (more than 99% of the total). By doing so,
it nearly emptied the primitive atmosphere carbon reservoir
(up to 97%), to be compared with the 280 ppmv of the preindustrial era. As burning fossil fuels transfers carbon from
the earth crust to the atmosphere, CO2SolStock (as CCS)
proposes to put it back where it comes from.
Figure 3. Carbon cycle, with reservoirs (Gt of C) and transfers from one to another (Gt of C/yr).
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
7
I.3 A “Future Emerging Technology?”
CO2SolStock was selected in the “Future
Emerging Technologies” (FET) section.
Within the call devoted to Energy, this
section was set to allow the exploration of
radically new “out-of-the-box” pathways.
The investigated topics were to be based on
strong science, with clear objectives in terms
of development, targeting proof-of-concept.
Also, this type of broad freedom of research
is considered by the Commission as “high
risk-high impact”: the energetic transition
needed by industrial countries clearly
demands new ways of tackling some of the
contemporary big issues such as the end of
cheap fossil fuels and climate change.
I.4 Carbon Capture & Storage
In this double context, carbon sequestration
is envisioned as one of the key technologies
to be deployed in order to lower the CO2
emissions levels of humanity. Until now, the
main approach by far has been what is known
8
as Carbon Capture & Storage (CCS). As
such, this industrial approach represents the
“default” process to which CO2SolStock will
explained.
CCS is a 3 phase process, each of
them bearing its cost in energy:
Phase 1 - Capture
Any method to produce the
of CO2
from stack of large emitters (coal or gas electrical plants,
steel or cement factories) .They are energy intensive and
demand an additional 25-40% of fuel, and therefore add-up
non-negligible CO2 load of emissions.
Phase 2 - Transport
The concentrated CO2 is transported by pipe-lines to the
storage sites. CO2 must be as pure as possible to avoid
corrosion.
Phase 3 - Injection and storage
Classical sites already used or envisaged include former oil
or gas reservoirs and deep saline aquifers, and to a
lesser extent unmineable coal seams.
Technical challenges:
Injection of CO2 at very high pressure (80
Injection of supercritical CO2 implies the existence of a
sealing cap rock in top of the storage site to avoid leakage
Social challenge:
The social acceptability of inland sites is low; hence favoring
the use of off-shore areas
In summary, like any emerging
industrial process, CCS will
need several decades to
be put in place, if at all: being
driven solely by climate change
policy,
CCS
development
recently suffered from the
economical crisis as it remains
heavily dependent of the
CO2 ton value.
RequiRemenTs foR a successful ccs pRojecT
Large point sources of co2
a transport system at an industriaL scaLe
Large capacity storage sites
Advantages of CCS
Potentially able to treat large
volumes of emitted CO2
Disadvantages of CCS
Can only sequester future CO2 emissions
only for big CO2 emitters
Huge storage sites are needed to justify the cost
of transport
huge infrastructure for transport that
is comparable to the one needed for oil and gas
combined
Risk of leakage due to storage at high pressure
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
9
II. CO2SOLSTOCK
OBJECTIVES
10
As an alternative way to sequester carbon
to complement the CCS schemes, the
biomimetic approach proposed in the project
had 3 objectives:
2. Establishing a methodology and a
testing toolkit enabling future research teams
1. Mapping the various microbiological
pathways of sequestrating CO2 through
carbonatation
3. Validating this technological strategy
with at least two novel recipes potentially
competitive and ready for a proof of
concept test.
similar pathways
co2solsTock: a biomimeTic appRoach To complemenT ccs
Predicted advantages
stable storage form:
sequestration of CO2 as a solid, even if it
could be dissolved in the long-run
No capture needed: this biomimetic
CO2 or organic carbon, hence saving
energy (see box below)
In line with some of the most recent
IPCC scenarios: it can sequester past
emissions, thus opening the avenue
for decreasing atmospheric CO2
concentration itself
Foreseen disadvantages
Calcium & other cations should not
originate from carbonate dissolution in
Need cheap & huge volumes of calcium
& other cations, as the volumes of CO2 to
sequester are huge
will be to keep the biological systems
functioning at all times, i.e. without
slowing down to a dormant equilibrium
dynamism and the complexity of
microbial communities
How to sequester past emissions?
Past emissions
already in the atmosphere
again in the earth’s crust, there is one easy way: capture the carbon using photosynthesis. As a
reminder, photosynthesis is a chemical process occurring mainly in plants and algae that converts
CO2 into organic compounds, especially sugars, using the energy from sunlight. This organic
material is then available as carbon source for any sequestration process.
Consequently, any organic carbon in wastewater that comes initially from photosynthesis can be
get back to the atmosphere as a result of microbial respiration corresponds to carbon sequestration.
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
11
III. CO2SOLSTOCK
EVALUATION :
A SYNTHETIC VIEW
12
calcium
caRbon
souRce
souRce
paThway
In saline
aquifers
Supercritical
CO2 or organic
soup
b. desalinaTion
& wasTewaTeR
Desalination
brine
c. silicaTe
Rocks &
paThways
a. subTeRRanean
eneRgy
deploymenT
needs
poTenTial
Organic soup to
inject
High: deep
injection
Unlikely
Wastewater
Waste water,
added if
necessary
Reduced:
transport of
ingredients
Early development
Silicate rocks
Wastewater
Waste water,
added if
necessary
Moderate: rock
treatment
Proof of
concept
Present on site
(wind, biomass,
bedrock)
Oxalates as a
by-product of
photosynthesis
Present on site
(wind, biomass,
bedrock)
Sun
READY TO
BE USED
wasTewaTeR
d. oxalaTecaRbonaTe
paThway
nuTRienTs
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
13
A.
Subterranean pathways using bacteria
in deep saline aquifers were shown to
be potentially complex and energy intensive
for low results in terms of carbon
sequestration. They might still prove to be
of interest for sealing of saline aquifers used
to sequester supercritical CO2 in some CCS
schemes.
B.
Using the same groups of salt-loving bacteria,
another approach sought to combine two
sources of industrial by-products:
desalination brines as calcium source &
domestic wastewater as carbon source.
The potential for precipitation of calcium
carbonate in terms of bacterial strains was
demonstrated in the lab, but the correct
recipe has yet to be worked out and
needs further experimentation. Issues
remain around the stability of the chemical
composition of the organic matter in
wastewater and on the affordability of this
carbon source.
C.
Dual wastewater anaerobic treatment
& silicate rocks weathering was the
acid attack on silicate minerals frees the
necessary calcium, while in a second stage,
other bacteria produce the alkalinity needed
to precipitate limestone and generate
high-quality biogas. The energetic cost of
providing and grinding the minerals will
determine the potential implementation
sites with a positive carbon balance for this
method, which is protected by a patent.
D.
Finally, an ecosystem management
approach was developed based on the
discovery of a triple symbiosis between
some special trees, fungi & bacteria,
leading to the precipitation of limestone
in acidic soils around and below the tree
roots. This particularity would allow
reforestation projects using these types
of trees not only to sequester additional
amounts of carbon, but also to correct the
pH of the soils and make them more suitable
for agriculture. Already known in dry areas
of West Africa, the phenomenon was shown
during the project to exist in other distant
tropical countries (Bolivia & India). It
will allow
forestry projects, such as the one recently
to the usual agro-forestry advantages
(sustainable agriculture, biodiversity, soil
maintenance, water balance).
wastewater treatment facility.
14
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
15
IV. CO2SOLSTOCK
PATHWAYS
This chapter describes each of the 4 pathways investigated by the
16
IV.1 Subsurface systems: Carbon sequestration in a
high pressure/high salinity environment
Saline
aquifers
are
subterranean
While exploiting the injection of CO2 via
CCS in subsurface structures, the objectives
of this research avenue were to test two
alternative pathways:
attractive
storage place for CO2 injection, with a
worldwide volumetric potential for storage
that could be as high as 10 000 Gt of CO2 (vs
the 40 Gt emitted per year by mankind)
feasibility of furthering and
stabilizing carbon sequestration as
precipitated carbonate in saline aquifers via
microbial activity
potentially be injected.
attractive
location
for
carbonatation: they contain ample
amounts of calcium and other cations,
necessary for the precipitation of carbonates
feasibility of recycling the
injected CO2, using microbes to convert it
into methane, a recoverable and valuable gas
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
17
Key facts on the subsurface environment
Injection of supercritical CO2 greatly challenges the survival
of subsurface bacteria
Living slowly: subsurface bacteria rely on poorly energetic
food
Results & main conclusions
Injection of nutrients such as cheap organic waste to
accelerate bacterial activity, is costly in terms of additional
energy
Subterranean bacterial activity is extremely slow, raising
weak yields for calcium carbonate and methane production
Remaining opportunity: boosting bacterial
CO2 containing subsurface pockets
Remaining opportunity: opportunities exist to
use the process for stabilization of civil engineering
structures (slopes, soils and bio-grouting). See also the dual
wastewater treatment opportunity p. 17
Contacts at the University of Edinburgh (UEDIN)
Dr. Bryne Ngwenya : [email protected]
Dr. Ian Butler : [email protected]
18
IV.2 Industrial ecology using desalination brines:
application to wastewater treatment
Greenhouse gas emissions of this sector
originate for a great part from the activity
of microorganisms, which treat, remediate
sewage and industrial wastewater by
degrading their organic matter content.
Union Greenhouse Gas Inventory (1990–
2009),
the
European
wastewater
treatment sector was responsible for the
emission of 28 Mt CO2 equivalents in 2009,
which represents nearly 1% of the total
emissions in the 27 European Member
States
caused
by
biofouling
and
mineral
scaling within wastewater treatment
equipment, when varying environmental
conditions (such as wastewater content)
are favorable to mineralization processes
induced
by
microorganisms.
Hence,
wastewater treatment settings already
encompass
environmental
conditions
and microorganisms which make CO2
biomineralization possible.
On the other hand, the desalination
industry is a fast-growing sector, producing
lots of high calcium content brines
as by-products, potentially available for
carbonatation reactions.
worldwide
has more than 700 plants producing
approximately 1,600,000 m³ of water each
day, or enough for about 8 million inhabitants
converted to limestone, this would amount to
0.6 Mt/yr.
The CO2SolStock approach was thus to
turn wastewater scaling problems into an
opportunity to promote carbonatation, and
thus, carbon sequestration.
The research objectives were :
produced from organic matter degradation
in wastewater treatment plants
favorable settings for biomineralization
to develop a high throughput carbon
sequestration industrial ecology system,
which combines the organic carbon
contained in the wastewaters with additional
calcium originating in desalination brines
thanks to salt-loving bacteria
Key facts on wastewater & desalination plants
Wastewater is an important source of organic carbon.
Desalination brines as a by-product is plentiful and rich in calcium
A large diversity of microorganisms already present in domestic wastewater have the potential to
induce the biomineralization of CO2
A similar diversity of microorganisms can precipitate carbonates in hypersaline environments
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
19
Results & main conclusions
Bacterial strains from wastewater & hypersaline
environments could be induced in the lab to precipitate
calcium carbonate separately
The recipe combining the appropriate carbon & calcium
source is yet to be found
Next development step: further optimizing the waste
recipes to obtain carbonate precipitation by bringing
together appropriate mixes of bacterial guilds,
organic and saline waste streams
Contacts at the University of Granada (UGR)
Dr. Marian Rivadeneyra : [email protected]
Dr. Jesús González López : [email protected]
Figure 8. Dual wastewater treatment & silicate rocks
process for carbon sequestration
20
IV.3 Dual wastewater treatment & silicate rocks
process for carbon sequestration
Current wastewater treatment results in
the production of CO2 and CH4 without the
opportunity for carbon sequestration and
energy recovery, with deleterious effects
for global warming. Without implementing
wastewater treatment to all urban areas
worldwide, CO2 and CH4 emissions
associated with wastewater discharges could
reach the equivalent of 1.91 X 105 t of CO2 per
day in 2025, with even more dramatic impact
in the short-term.
wastewater treatment have enormous
potential, as it could add energy conservation
incentives to upgrading existing facilities to
complete wastewater treatment. Biological
processes in water and wastewater treatment,
such as the worldwide used Anammox
process, which combines an acidifying
process followed by an alkaline process, could
have potential for CO2 sequestration. While
and fermentation process, alkalinity could
production and desulphurisation.
Microbial silicate rocks weathering is an
important natural process at the global
carbon geo-cycle scale. This natural
phenomenon inspired a dual process through
dissolves silicate rocks containing calcium,
and alkaline neutralization in separate
reactions. One of the best mineral candidate
was wollastonite, with worldwide reserves
exceeding 90 million tons, and probable
reserves estimated to be 270 million tons.
Hence the research objectives of this
CO2SolStock pathway were to demonstrate
the feasibility of a two-stage wastewater
treatment process leading to carbon
sequestration, where:
dissolution of silicate
rocks or minerals via microbial activity
generating acidity solubilizes calcium ions
formation of calcium
carbonate and biogas via microbial
activity introducing alkalinity in organic
carbon rich industrial wastewater
ANAEROBIC WASTE /
WASTEWATER TREATMENT PLANT
Mine
Improved Biogas
Limestone
Silicate Mineral
Ca/Mg Source
Methane gas
Acidogenic
Methanogenic
Sequestered CO2
Avoided CO2
Carbon containing
Re-use in
Waste/Wastewater
construction
Ca
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
21
Key facts for dual wastewater treatment
Industrial wastewater is an important source of organic
carbon
Silicate rocks & minerals are abundant and provide a rich
source of calcium
Acid producing & methane producing bacteria can thrive in
carbon rich and oxygen deprived environments
Results
Ground wollastonite, amongst calcium silicate minerals,
was the most easily dissolved by acidogenic attack, thus
providing calcium for the next step at an acceptable speed.
The second step will generate high quality methane and
calcium carbonate.
Carbon sequestration impact
A large paper-mill operating such a facility, with 20 000
m³/day water treated and 30 Kg COD/m³, would sequester
around 100 tons of CO2 per day (by producing around 300
tons of calcium carbonate/day).
Compared to a conventional mineral CO2 sequestration, the
avoided chemical, mechanical and thermal pretreatment
reduces the carbon impact and saves 50% of the cost per ton
CO2
Generation of a biogas (methane) with an improved quality
of 20%, as compared to biogas quality currently being
recovered within the wastewater treatment sector
Silica is a side product of stage one
22
Potential developments
This process is covered by a patent application
20.05.2011 by TU Delft (NL2006819):
Joint cooperation with ore/mining partner involving market
Steel, and more generally, alkaline slag by-product producing
industry:
Their high calcium content could be recovered during the
while the heavy metals they contain could be trapped as
precipitated carbonate during the second stage
Road construction and more generally civil engineering
industries which may have suitable calcium source of
silicate, as their regular output:
The ingredients required for C sequestration/
biocementation would be easily mixed in quarries
For sub-base replacing of Portland cement
For embankment steeper, hence permitting the
construction of less invasive slopes
For environmental contractors: valorization of waste
disposal sites
Waste material C6H12O6
Silicate Mineral CaSiO3
Methane CH4
LAND FILL SITE
Ca (C2H3O2)2
+
CO2
Acidification Phase
5 years
Carbonate Mineral CaCO3
Methanogenic Phase
10 - 20 years
Contacts at the Delft University of
Technology (TUDelft)
Shiva Shayegan Salek :
[email protected]
Prof van Loosdrecht (2012 Lee Kuan Yew Water Prize
award): [email protected]
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
23
IV.4 The oxalate-carbonate pathway:
turning sunlight into stone
Compared to the 3 other CO2SolStock
pathways, all envisaged within industrial
settings, the oxalate-carbonate pathway
(OCP) differs by proposing ecosystem
management to sequester calcium carbonate.
The ecosystems from which it originates are
African forests, themselves under pressure
and current source of carbon emissions.
Indeed, beside the various sectors emitting
CO2 from the intensive use of fossil fuels,
deforestation & carbon loss from soils
are still important drivers of greenhouse
gas production. The deforestation and forest
degradation averaged 1.2 Gtons of carbon
per year over the period 1997–2006. Overall,
albeit decreasing, it still accounted for about
12% of CO2 emissions in 2008.
Within the Kyoto Protocol, this importance
of deforestation has led to the adoption of
the “REDD” initiative in December 2010
by the COP-16 (Conference of the Parties to
the UNFCCC), for reduced emissions from
deforestation and forest degradation. The
idea behind this scheme is that by reducing
deforestation rates by 50% by 2050 and then
maintaining them there until 2100 would
avoid emitting the equivalent of 12% of the
emissions needed to keep atmospheric CO2
concentrations below 450 ppmv.
It is in this context that the Swiss team of
Professor Verrecchia made an important
discovery around 2000 in West Africa, which
allowed the oxalate-carbonate pathway to be
explored in details:
24
Milicia excelsa) was shown
to display a surprising phenomenon: it
accumulates mineral carbon as calcium
carbonate (CaCO3) within the roots and in
the soil, even in acidic conditions
with fungi and bacteria making use of the
oxalates produced by the tree
thus constitutes a mineral carbon sink in
the soil, in addition to the two usual forest’s
organic carbon sinks, consisting of the tree
itself and the soil litter
deforestation of Iroko
trees (as a valuable wood) is in Cameroon
alone responsible for the loss of as much
as 2.6 Mt of carbon per year, released to
the atmosphere as CO2
Within CO2SolStock, the research objectives
were :
search of the OCP
interactions between the tree, the fungi and
the bacteria, to allow an optimization of the
limestone producing reaction
quantify the carbon sequestration impact
What is the OCP?
It consists of combined biological activities of the tree,
fungi and bacteria that promote the biomineralization
taken up by the tree via photosynthesis to build up biomass.
This biomass is then partly transformed into oxalate
ions which, as the tree grows, accumulate on the ground
surrounding the tree and the tree litter. These oxalates
then become a food source for soil oxalotrophic fungi and
bacteria, resulting in the formation and accumulation of
carbonates that precipitate with calcium to form calcium
carbonate.
Figure 9. Diagram showing the main
trees ecosystem, adapted from Michel
CO2
Biomass
Oxalate
Calcium Oxalate
Fungi
Oxalate
Oxalate
Ca²
Bacteria
Bacteria
Ca² +
Limestone
Limestone
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
25
Key facts on deforestation
& oxalate-carbonate pathway (OCP)
Deforestation is a major source of CO2 emissions.
Some tree species, including the Iroko tree, present a
particular metabolism in symbiosis with soil fungi & bacteria
leading to calcium carbonate accumulation in the soil.
These species have a high potential for reforestation projects,
including within agro-forestry schemes.
Main results
Investigations during CO2SolStock have contributed to
various progress:
The OCP is a widely distributed phenomenon, as it could
be detected for several plant species from three continents
(Africa, India, South America): it implies a massive increase
of the extent of potential sites for ecosystem-induced
carbon sink formation
Fungal soil species are key enablers of the OCP and
are therefore key for the formation of carbonates. Without
them, the bacteria cannot do the work
Although Iroko trees start very early to accumulate calcium
carbonate, it might take up to 80 years before a major switch
from acid to alkaline conditions in the soil. This shift in pH
was already exploited by local populations for agriculture
OCP trees can precipitate carbonates on soils with calcium
silicate bedrock, far from any calcium carbonate rocks
Carbon sequestration impact
The carbon sequestration potential of the OCP depends
greatly on the tree species, the tree’s age and the
availability of calcium in the tree surroundings.
On average up to 21 kg of CO2 can be stored as CaCO3 per
tree and per year
Hence an agroforestry project (see the following box)
where 200 “OCP trees” per hectares are planted could bring
26
up to 4.2 tons of CO2 stored as CaCO3 per hectare
and per year, in addition to the carbon stored as biomass
(plants, soil organisms, decaying organic matter)
More generally and when compared to “classical”
reforestation schemes, the OCP trees have the big advantage
eventually release CO2 during their decay (known as leakage
in the REDD discussions), limestone is stable in dry soils for
at least thousands of years
Figure 10. Calcium carbonate rocks
formed under the roots of an Iroko tree
in Cameroon. The right picture gives
Cailleau.
ecosystem-induced carbon sink
Improvement of soil fertility, thus positively
impacting on:
bio-availability of soil elements such as potassium,
sodium, and potentially phosphorus
soil biodiversity
water retention
Presents also all the advantages of forest preservation
and reforestation, including their positive impact on
water cycles and climate
Local economy and food security: the OCP-displaying tree
ecosystems could be used in agroforestry schemes to
not only store carbon as mineral rock and biomass, but also
for wood production coupled with sustainable & local
agricultural practices
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
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What is Agroforestry?
According to the World Agroforestry Centre, agroforestry is “a
collective name for land use systems and practices in which woody
perennials are deliberately integrated with crops and/or animals on
the same land management unit.”
Among its advantages, agroforestry:
Maintains the soil’s natural resource and carbon sequestration
capacity
Potentially reduces to zero the use of classical fertilizers and
pesticides via ecosystems regulating mechanisms
crops, etc)
This agroecological practice can be set according to different
degrees of land use intensity, from near natural forest management
to intensively managed agroforestry systems. Altogether, these
agroforestry practices are environmentally-friendly, tend
to provide very good production yields and are labour
intensive, which is of socio-economical importance for local
populations.
They offer a perfect context for reforesting with a mix of species
including the OCP trees.
28
Current output and potential next
development steps
The “Saving Trees” program: an ongoing project, involving the French
Institute of the Yves Rocher Foundation and Jean Hervé company,
coordinated by the NGO Biomimicry Europa, has been launched in
2010 to grow around 80 000 Maya nut trees (OCP displaying trees)
in Haiti. This program involves teaching agro-ecological practices
to local population on how to grow, take care of the tree and harvest
its nuts, which are of great nutritional value, make use of its sap and
leaves to feed the cattle.
Future cooperation-development projects for the South
Similar programs could be used to sustainably grow Iroko trees,
which wood is considered as precious wood.
Collaborations with world-class agroforestry researcher
teams are needed to optimize the plants associations in terms
regimes, etc. Example: World Agroforestry Centre in Nairobi, CIRAD
in Montpellier.
Collaborations with
to extend
the search for other suitable sites, to select the companion crops and
to optimize the economical returns as early as possible. Example: the
IAFN network.
Carbon market and reforestation initiatives
international NGOs specialized in carbon markets and
reforestation to:
form
Sell it to foundations searching for philanthropic innovating projects
and big companies in need for carbon compensation (see UN-REDD
program)
Contacts
Maya Nut tree program, Dr. Daniel Rodary :
[email protected]
To launch new projects, address reforestation & carbon market, Dr.
Caroline Zaoui: [email protected]
Neuchâtel (UNINE) Dr. Eric Verrecchia : ERIC.VERRECCHIA@
UNIL.CH Dr. Pilar Junier : [email protected]
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
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V. WHAT WE LEARNED
30
V.1
Mitigation impact on atmospheric CO2
Criteria considered:
CO2 sequestration potential
Investment & risk of completion
divided in three areas: low or even negligible
investment, with long term payout, medium
investment, requiring a medium payout and
a high investment, high pay-out opportunity.
FOSSIl fuel
power
station
CO2 EMISSIONS SCALE
Incremental
Sequestration Overtime
& Raising Number of
Planted trees
CCS
UEDIN
Biomineralisation
Seal in Saline Aquifers
Smaller scale
emitters
Reforestation &
Agroforestry:
+++ Population
& Ecosystems
Benefits
UNIL / UNINE
Oxalate-Carbonate
Pathway in Soil
+
Methane
& SiO2
TUDelft Dual Process
Acidifcation / Alkanisation in
Wastewater treatment plants
UGR Industrial Ecology process
in Wastewater treatment plants
Investment efforts & Risks of completion
+++
Figure 12. Carbon sequestration potential and investment risk of the investigated pathways.
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
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A. Subterranean biomineralization
sealing in saline aquifers:
It is probably only a potential
slight improvement of a “classical”
CCS technique, hence suffers from
emitted CO2 by all the European power
producers would convert to more than
one billion kilotons carbonate every year.
against the leakage risk associated with
injecting CO2 under pressure, which is
amounting to 300 €/ton CO2 leaked
C.
alkalination process:
life cycle analysis
from the silicate grinding stage to biogas
and limestone recovery, in order to
determine the potential implementation
sites
wastewater carbon of the pulp & paper
industry would produce up to 10 million
ton limestone a year
D. Reforestation projects and the OCP
phenomenon:
Common to pathways B and C:
low-tech/ low
investment type
Sequestration
of
organic
carbon
, usually
ending up as emitted CO2 during wastewater
treatment, constitute a medium sized
option. Existing facilities could be adapted
to technologies developed by the project.
B.
availability of calcium for precipitation is
to use industrial calcium containing
waste streams, such as desalination brine.
Industrial ecology approaches bring great
hopes of solutions, as they might associate
brines from desalination plants (the calcium
being in ample supply in the ocean) with
industrial wastewater and alkaline industrial
32
Long-term results
additional society-ecosystem
account for 5 to 10 % of tropical round
wood production, might reach 1 Mt of
precipitated carbonates per year in Africa
alone. As shown during the project,
other suitable areas include at least Latin
America & India, so the sequestration
V.2
What about the ocean?
Because of the need for a better grasp of
the global calcium cycle, the consortium
also came to a better understanding of the
effect of the actual & future levels of
atmospheric CO2 on the ocean acidity.
In particular, the feedbacks between
terrestrial rock weathering & carbonate
sediment precipitation in the oceans
were looked at from an alkalinity/acidity
perspective and compared to the existing
pre-historical record. A number of remarks
can be deduced from the available science:
ocean water absorbs about 50%
of the excess CO2 dumped annually
by humankind in the atmosphere, at the
brings a correcting alkalinity 100 times
lower as the one needed to keep the ocean
pH stable at the actual pace of CO2 injection,
while this injection pace is accelerating
activity can be brought down to 0, before
switching to a source of CO2 emissions
back to the atmosphere, with catastrophic
effects on marine food chains and
time recovery for the ocean carbonate
balance and marine biodiversity was of
several 10,000 years for such previous
100 times slower than the one induced by our
current fossil fuel economy
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
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V.3
CCS & CO2SolStock impact on climate change
Confronted by the climate change pressure,
what’s the role of carbon sequestration?
Looking at both CCS & CO2SolStock, the
main facts we can put together are that:
to sequester past emissions via
CO2SolStock technologies and other
bio-assisted processes to be developed
CCS mitigation is not yet adopted by
society, for cost and public perception
issues. An effective implementation
could take decades, from the industrial
development -at least 25 years- to its full
impact on emissions, another 25 years
concentration in the atmosphere, using both
approaches is useful, as any kg of CO2 back
to the lithosphere (or earth crust) represents
a gain of time...
CCS can only
sequester 75% of the CO2 produced by
the big emission industries
technologies’ full deployment: the cost of
the CO2 ton is around 10€ in 2012, while
the avoidance cost per ton for CCS is still at
35€ per ton of CO2 for coal, and at 90€ per
sequestration of future emissions
via CCS is not enough: we also need
CO2 Avoidence cost without
transport and storage cost.
100
Pre-combustion
Eur / t CO2
80
Post-combustion
Oxyfuel
Power plant
and CCS
technology
improvement
potential
60
40
20
Hard Coal
34
Lignite
Natural Gas
V.4
Calling for a paradigm shift
The use of both CCS & CO2SolStock
approaches altogether won’t be
enough.
In fact, any carbon sequestration
scheme does not justify further
emissions: mankind simply needs to stop
emitting, and this implies a very serious
and collective work on the compatibility
of our activities & behavior with the
biosphere and the planet.
sustainable businesses which do not need
fossil fuels. Such promising approaches are
already on the shelve, awaiting appropriate
tax incentives to see light:
- Agroforestry
- Ocean food resource husbandry
- Industrial reconversion from petroleum
based chemistry to biomass populationecosystem responsible chemistry
priority on switching from stock energies to
our industrial society: we have to reallocate
its albeit limited funds to developing
V.5
our energy needs
Stakeholders’ responsibility
Should the price of the ton of CO2
alone determine a decision to invest in
carbon sequestration schemes?
Investing in pilot projects and supporting
their development has other advantages for
the sustainability of the companies:
about the will to participate to the necessary
post-carbon paradigm shift
inventing a truly sustainable way of living
collaborators
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
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VI. NEXT STEPS
36
VI.1 Paradigm shift innovation opportunities
Because it can deal with CO2 that could be
out of reach of classical CCS, the CO2SolStock
approach is complementary to CCS.
Compared to CCS, the bio-carbonatation
pathways represent a radically new approach, as:
opportunities rejecting organic carbon as a
be either stored or could potentially be used
as a building material under various forms
carbon is from photosynthetic origin,
hence originally pumped by plants from the
atmosphere
counter-ion necessary to form carbonates:
- calcium either as an industrial byproduct, or weathered from silicate rocks
- other cations that could be turned into
stable carbonates, like Mg & Fe, but
also undesired elements such as heavy
metals, thus leading the way to new bioassisted remediation techniques
Furthermore, once fossil fuels exploitation
will stop (and CCS with it) the CO2SolStock
approach will remain both needed (to
sequester the excess CO2 from the
atmosphere) & applicable.
temperature/high pressure chemistry, if at all
VI.2 A call to further cooperation
Further exploitation to be developed:
desalinization brines and wastewater could
in wastewater treatment could be extended to:
- Quarries, civil engineering industries
which may have suitable calcium source
of silicate, as their regular output
Road
construction
industry
(which could then make good use
of the carbonates obtained such as
biocementation,
avoiding
Portland
cement)
- The acceleration of atmospheric
CO2 intake in the system via the carbonic
anhydrase biocatalyst directly produced
by living microbial populations
- A collaboration with teams working
on micro-algae (like diatoms and
cyanobacteria) that pump atmospheric
CO2 to generate more readily bioavailable carbon source for calcifying
microbial guilds
- Steel, and more generally, alkaline slag
by-product producing industry
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
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to the OCP phenomenon need the joint
forces of:
agroforestry researcher teams for
exciting opportunities to develop joint
research & development projects to
implement agroforestry programs.
Such programs would be set to validate
value of OCP farming systems in the
light of climate change mitigation
and food production & security
- International NGOs specialized in
carbon markets and reforestation
carbonates as a carbon storage & to
sell it to foundations searching for
philanthropic
innovating
projects
and big companies in need for carbon
compensation
38
CO2SolStock innovations:
- Exploitation of live carbonic
anhydrase producing bacteria to
enhance the rate of CO2 transformation
as carbonate in wastewater treatment
settings
- Bio-grouting under roads, railways
or for embankments as carbon storage
sites
: this opportunity proposes to
exploit industrial ecology principles to
valorize industrial by-products and drive
their maturation and stabilization at waste
disposal sites towards carbonatation
(patent application EP20110153851)
air will stay in surface reservoirs and won’t go back into
us is that there’s a limit on how much we can put in the air
without guaranteeing disastrous consequences for future
generations.
James Hansen, director of Nasa’s Goddard Institute for
Space Studies, March 2012
Deliverable 8.8: CO2SolStock outreach synthesis report April 2009 – March 2012
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CO2SolStock
www.co2solstock.eu
@CO2Solstock