Getting insights into subsurface methanogenesis processes at lab scale within a CO2 Geological Storage and bioconversion context

Abstract:

Among the various Carbon Capture Utilization and Storage (CCUS) strategies, CO₂ geological storage in deep saline aquifers represents a viable mediation solution for reducing the anthropogenic CO₂ emissions. So far, little is known about both the CO₂ storage impact on the underground geochemistry and on the microbial diversity inhabiting deep aquifers. Consequently, this kind of storage requires adequate scientific knowledge and tools at the pore scale to evaluate injection scenarios, to estimate reservoir capacity and to evaluate the reverse impact of the deep biosphere on such human activities.

In this context, research projects gathering interdisciplinary partners (chemists, physicists, experimentalists, materials scientist, microbiologists and geologists) are highly desired to be able to address part of these lacks of knowledge.

This presentation will highlight in particular a large French research project dealing with new experimental tools allowing for investigating the coupled mechanisms (i.e. thermodynamics, hydrodynamics, chemistry and biology) involved in such storage processes at the pore scale in lab environment. These new experimental devices are porous media designed inside high pressure / high temperature microfluidic reactors (micromodel or geological labs on chip – GloCs [1]). They turn out to be excellent tools to complement the classical core-scale experimental approaches to investigate the different mechanisms associated with CO₂ geological storage and bioconversion in deep saline aquifers [2]. The specific interaction between the deep underground life and CO₂ geological storage is of particular interest given that such microbial life could be shaped by human activities, while bringing outstanding feedbacks on CO₂ pricing through biovalorization.

We will introduce the use of on-chip biocompatible high-pressure geological laboratories (BioGloCs) for the culture and the study of methanogens living in deep geological environments. As part of the "BIG MAC" ERC project [3], which aims at mimicking deep geological environments, we study the bioconversion reactions of CO₂ into methane by methanogenesis. BioGloCs are significant tools to mimic the in situ biogeological reservoirs conditions to study CO₂ bioconversion within deep aquifers. These tools could provide new insights into bioremediation process to restore CO₂ as a valuable energy resource (i.e. CH₄ via methanogenesis process) and could also find wider applications in geological-related and deep-sea field studies (e.g. Enhanced Oil Recovery, shale gas recovery or geothermal energy).