FAQ

A. What's the project global objective?
B. On what basic principles is the project based?
C. What are the ingredients which are necessary to the precipitation of carbonates?
D.Where are the microorganisms to be found?
E. How fast is this natural process?
F. What is the potential of this approach for carbon sequestration?
G. Will you use Genetically Modified Organisms (GMOs)?
H. Where will the experiments be carried out?
I. What would be the advantages of this project?
J. What are the challenges of this project?
K. Is it geo-engineering? What’s your position on it?
L. Do you think that developing carbon sequestration schemes could diminish the incentive for greenhouse gas emission reductions?
M. What are the respective roles and activities of each team in this project?

A. What's the project global objective?

The objective of the project is to achieve the feasibility of sequestering CO2 in the form of carbonates precipitated by micro-organisms, with the aim of developing the selected process at an industrial scale. Various ways of forming carbonates by microbiological means will be investigated, tested and pushed as far as possible towards a pre-industrial stage.

B. On what basic principles is the project based?

It is of course well known that CO2 is utilized in various ways by living organisms.

The first that comes to mind is photosynthesis: the light energy allows green plants (and some micro-organisms) to combine CO2 with water in order to produce sugars and other components. In this case, CO2 is trapped in the form of organic matter.

A less known pathway is when CO2 is mineralized in the form of carbonates. For example, it constitutes the basic principle of shell formation for mollusks as well as other marine groups. Similarly, this process of lime precipitation can also be triggered as a consequence of bacteria’s metabolism. This microbial carbonatation process is responsible for the formation of about 40% of the world chalks (calcite) cliffs, in addition to the remains of calcareous plankton.

It is this microbially-induced carbonatation process, to be found in various habitats, which CO2SolStock is studying as a potential tool for carbon sequestration.

C. What are the ingredients which are necessary to the precipitation of carbonates?

Carbon, either originating from CO2 or organic matter;
Divalent cations: calcium (Ca2+), magnesium (Mg2+);
Alkaline conditions (high pH values).

D. Where are the microorganisms to be found?

Microbes precipitating carbonates occur in many different habitats. Such bacteria exist in marine sediments, in hot springs, some hydrothermal vents, various types of soils and also hypersaline environments. Some bacteria also produce limestone derived from chemical compounds excreted by mushrooms and tropical trees. Finally, bacteria also precipitate carbonates in man-made pipe and tubing transporting water, a phenomenon known as ‘scaling’ and usually a problem for the industry.

E. How fast is this natural process?

It varies depending on the bacteria involved and the habitat conditions. For example, some African trees and their surrounding bacterial community produce up to 5 kg CO2 equivalent every year. On the other hand, using some other soil bacterial enzymes has allowed other researchers to precipitate in 5 hours 40 kg CO2 equivalent into a cubic meter of sand.

F. What is the potential of this approach for carbon sequestration?

It is probably considerable. Fine tuning and extending naturally occurring processes could store huge volumes of CO2. On the other hand, many industrial processes produce vast amounts of CO2, organic matter and/or calcium as waste. In both cases, it would be a rather logical way to put carbon back in the soil, or in the lithosphere, where it used to be as a fossil fuel. There are large emitters, such as power plants that produce tens of thousand tons CO2 a day, which, converted into carbonate, would also amount to tens of thousand tons a day. The production and use of such amounts of carbonate are within the scope of our project, whether the emitters sequester the actual CO2 they emit, or reach for atmospheric CO2 elsewhere to compensate. Yet, it remains difficult to put accurate figures at this stage, but it is also amongst the objectives of the project to better answer this question.

G. Will you use Genetically Modified Organisms (GMOs)?

There is no need for GMO's. The micro-biological processes available in nature are already tuned to environmentally satisfying conditions. Furthermore, the number of metabolisms available in this realm is known to be considerable. It is much more attractive to test what already works without risking adverse environmental problems. Hence, CO2SolStock will not develop or try any GMOs. Similarly, any introduction of non native bacterial strains will be considered with extreme care.

H. Where will the experiments be carried out?

They will be carried out in the four labs, depending on the expertise of each university. Experiments in the field are considered only for species which already exist in the potentially favorable habitats. For example, measuring the ability of trees to naturally precipitate carbonates together with micro-organisms, in order to exploit this ability, e.g. via reforestation.

I. What would be the advantages of this project?

In terms of stability: CO2SolStock (as other non-biological proposed CCS schemes), proposes to sequester CO2 as a solid instead of a gas. Even if this solid (e.g. limestone) can be dissolved in the long-run, it is of course much more stable than its storage as a supercritical gas, the most common scheme proposed so far.
In terms of energy demand: As the fixation would be done by micro-organisms, it would use low-energy and would be done under ambient temperature. By relying on either atmospheric CO2 or organic carbon (itself of atmospheric origin through photosynthesis), CO2SolStock would in most cases avoid the energy-intensive step of CO2 concentration conventional in other Carbon Capture & Storage techniques.
In terms of carbon source and climate change mitigation: Being able to use atmospheric CO2, opens the avenue for eventually decreasing the CO2 atmospheric concentration itself, as requested by some of the most recent IPCC scenarios.

J. What are the challenges of this project?

The source of calcium or other cations: the potential volumes of CO2 to sequester are huge, and thus so are the volumes of calcium. The challenge will be to find sources of cheap and abundant calcium (or other cations) not originating from carbonates dissolution in the first place.
Mass balance and flow: the difficulty will be to keep the biological systems functioning at all times, i.e., without slowing down to a dormant equilibrium.
Heterogeneity and up-scaling: bringing processes from the Petri dish to the industrial level is a real challenge, given the dynamism and the complexity of microbial communities.
Early involvement of industries: so as to develop applicable and cost effective processes. One way will be to couple sequestration with side-benefits, such as energy savings or materials cycling.

K. Is it geo-engineering? What’s your position on it?

The US National Academy of Sciences has defined geo-engineering as "options that would involve large-scale engineering of our environment in order to combat or counteract the effects of changes in atmospheric chemistry." In that sense, some of the avenues under scrutiny in CO2SolStock can be considered as geo-engineering. For example, fine tuning microbial processes naturally occurring in soils and producing carbonate rocks could be investigated, as long as it only accelerates natural occurring phenomenon, and after an environmental assessment.

However, we agree with John Shepherd’s comments, from the University of Southampton, and Chair of the UK Royal Society report on geo-engineering: “…we are not advocates of geo-engineering - our opinions range from cautious consent to very serious skepticism about these ideas. It is not an alternative to emissions reductions and cannot provide an easy quick-fix to the problem…”

L. Do you think that developing carbon sequestration schemes could diminish the incentive for greenhouse gas emission reductions?

First of all, we think that not emitting CO2 in the first place remains amongst the cheapest and most effective answer to the climate crisis. However, we also think that the climate situation is serious enough to justify the need of techniques that are able to transfer CO2 from the atmosphere back to the soil. They will be needed even once we’ll have reduced our collective CO2 emissions.

M. What are the respective roles and activities of each team in this project?

Four universities and one SME are involved in this project according to their field of specialization and investigation.

University of Edinburgh (UEDIN): this team has a long experience in deep subterranean habitats like depleted oil or gas reservoirs, saline aquifers and hydrothermal/geothermal environments, and is well equipped to work with these deep habitat conditions. They are also the coordinators of the project.
University of Granada (UGR): This team accumulated in-depth knowledge in bacterial living in lagoon and other hypersaline environments. They have identified 20 different carbonate precipitating bacteria and are analyzing their metabolism.
University of Lausanne (UNIL): this team is specialized in bacteria living in terrestrial environments such as tropical soil, and especially the carbonating groups feeding on oxalates. They use spectral analysis and numerical models simulating organo-mineral growth to demonstrate the significance of carbonatation in tropical soils.
Delft University of Technology (TUDelft): the team is specialized in process engineering applications of microbial ecosystems and in computational models combining microbial and chemical conversion with mass transportation in complex geometrical systems like soil. They are familiar with environmental assessments and public perception analyses.
Biomim-Greenloop (BG): is a young SME whose mission is to provide services in environmental, climate and sustainability problems, taking inspiration from living organisms and ecosystems for finding appropriate solutions. BG has identified bacterial carbonatation as a mean to sequester CO2, set up the team and built up the whole project in partnership with the universities. BG is also responsible for the first linking with potential industrial partners and for the results dissemination.

As the project management structure is transversal, each partner is involved in the 6 work packages (WP). The dissemination activities (WP8) will take place during the whole course of the project. Each partner leads one of more WP’s according to their specialization:

BG leads the 1st WP – literature scrutiny;
Granada leads the 2nd WP – bench testing habitat/bacteria systems & modeling;
Edinburgh leads the 3d – Testing toolkit- and 6th WP – Meso-scaling up proof of concept parameters. Besides, Edinburgh is also the project coordinator;
Lausanne leads the 4th WP – bacterial system optimization;
Delft leads the 5th WP – overcoming key roadblocks.