Pore-scale modeling of microbially enhanced carbon mineralization

Large-scale implementation of geological carbon sequestration is considered as a key strategy to limit anthropogenic warming to 1.5–2°C, as set out in the Paris Agreement. We are interested in a viable alternative represented by injecting CO2 into reactive rock formations, e.g. basalts, to facilitate rapid carbon mineralization, and therefore increase storage security. Our particular interest lies in microbially enhanced carbon mineralization: biological catalysts are utilized to alter reaction rates and further enhance carbon mineralization.
In this talk, we propose a micro-continuum formulation of coupled flow and bio-geochemical reactive transport at the pore-scale, in which the reactive transport model is fully coupled with a biomass-nutrient growth model. In order to assess the role of biological catalysts in enhancing carbon mineralization, we present simulations results of an application case of carbon mineralization in an idealized porous geometry with and without biomass growth at realistic conditions relevant to CO2 storage in ultramafic rocks. Results clearly highlight the role of the biomass in enhancing the pH of the aqueous solution, a process called "bioalkalinization", thereby leading in a highly non-linear way to enhanced calcite precipitation, resulting in an interesting potential methodology for CO2 immobilization.

Contatti:
alessio.fumagalli@polimi.it
anna.scotti@polimi.it