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

Massive storage of dihydrogen (H 2) in underground geological storage (UGSs) will be necessary to meet future H 2 production ambitions. Such storage in deep aquifers was simulated in a high-pressure reactor, and the evolution of the 3 phases (natural gas/H 2 , formation water and rock) with autochthonous microorganisms was monitored over several weeks. These results show that methanogens do not necessarily dominate the community, but that sulfate-reducing activity and formate bioproduction are systematically present. The experimental data were fed into a biochemical model in PHREEQC to better understand the interplay between the phenomena observed. In particular, it was shown that the microbial activities associated with H 2 consumption led to alkalinisation, which could explain, at least in part, the slower rate at which H 2 disappeared, even if sufficient CO 2 and sulfate remained in the system. Combined with a supposed local nutrient depletion, these results are encouraging for H 2 storage in deep aquifers. • Injection of H 2 in three deep aquifers was studied in a high-pressure reactor. • Multidisciplinary approach including experiment analyses and biochemical modeling. • Low sulfate content sites should be favored for H 2 storage in deep aquifers. • Storage behavior needs to be studied site-specifically. [ABSTRACT FROM AUTHOR]