Interplay between microbial activity and geochemical reactions during underground hydrogen storage in a seawater-rich formation

Subsurface hydrogen storage would be one of the main possible solutions for a successful energy transition in the future of world energy. However, hydrogen gas is an electron donor which may lead to microbial activity when storing hydrogen in the subsurface. Methanogenesis, acetogenesis, and sulfate reduction are the primary biological reactions that can lead to hydrogen loss through biochemical processes. This paper presents a novel bio-geochemical modelling approach which considers the kinetics of microbial reactions as well as the equilibrated geochemical reactions in the context of underground hydrogen storage. The findings demonstrate that the type of mineralogy and formation water composition may greatly influence biochemical reactions and thus potentially the storage/recovery performance of hydrogen. This study provides a detailed comparison and analysis of the behaviour occurring in calcite, dolomite, and quartz systems assuming the North Sea seawater composition as the in-situ brine. It is found that dolomite is the least favourable mineralogy in terms of hydrogen loss and hydrogen sulfide production, while calcite and quartz are better suited in a seawater-rich environment.