EML Seminar: Geological storage of dihydrogen in deep aquifers

The development of green hydrogen, produced from renewable or low-carbon energy sources, requires the development of large-scale, safe, and economically viable storage solutions. H2 storage in salt caverns has been known for about fifty years, and depleted hydrocarbon reservoirs have been the subject of several studies in recent years, but we still have very little information on deep aquifers, which would represent the largest geological storage volumes. These oligotrophic microbial ecosystems host hydrogenotrophic populations capable of interacting with stored gases (sulfate reducers, (homo-)acetogens and methanogens) and becoming artificial SLiMEs (Sub-Lithoautotrophic Ecosystems). Our studies suggest that microbial communities responding to gas storage can durably alter the physicochemical conditions of the aquifer. Using high-pressure reactors, we simulate the three phases of these systems (gas, water, solid) in the presence of indigenous microorganisms. We study the evolution of the taxonomic diversity of these communities, as well as that of the three phases, in order to understand their dynamics.