Comparative study of three H2 geological storages in deep aquifers simulated in high pressure reactors.

In the context of climate change and resource depletion, an adaptation in the energy mix towards decarbonation and renewable energy is crucial. Dihydrogen (H2) is a promising alternative to traditional carbonated energy sources. Besides being storable, it also has the potential to be produced using renewable and low carbon processes. In order to use H2 on a large scale, it will be necessary to store massive quantities by means of, for example, Underground Gas Storage (UGS) in deep aquifers. H2’s behavior in deep aquifer is related to its geochemical reactivity and to the microbial activity. Also, it is an electron donor as well as an energy source for numerous indigenous microorganisms. In this study, H2 injection in three different UGS, with different formation waters, rocks and microbial communities, were simulated in a high-pressure reactor following a previously defined protocol [1]. To better understand the intricate phenomena at work, extent of reaction equations based on microbial diversities were solved to identify the main reactions taking place in the reactor. The broadly used geochemical modeling software PHREEQC was used to calculate gases solubilities, resulting pH and redox potential inside the reactor.