Field-Scale Reactive Transport Modeling of Bio-Methanation During Underground Hydrogen Storage in Saline Aquifers

Abstract In the context of underground hydrogen storage in saline aquifers, hydrogen is in direct contact with the formation brine, which rises various concerns about the dissolution of hydrogen in water, and the microbial/abiotic geochemical reactions that may occur consequently. In this study, we expand on the knowledge of the microbial reactivity during underground hydrogen storage in saline aquifers, in particular, the methanogenesis reaction that consume the hydrogen and carbon dioxide to generate methane. This study delves into the impurity-induced geochemical reactions on a field scale level. Through utilization of kinetic parameters from the experimental data, and advance computational modeling, we elucidate the mechanisms governing this reaction and their consequences for storage efficiency, safety, and environmental impact. On the other hand, the potential of methane formation in the presence of microorganisms and CO2 poses a critical challenge to hydrogen storage. The presence of microbes under appropriate conditions can lead to a considerable loss of hydrogen, with 10-50% of hydrogen being consumed in the methanation reaction. This phenomenon is considered a significant hurdle in the practical implementation of hydrogen storage technologies, and a carful microbial analysis of the existing brine is a crucial step to be considered during the initial stage of screening process. Here, we present a reactive transport model on a field-scale level to enhance the comprehensive characterization of hydrogen behavior and its ultimate fate within reservoir systems. Our investigation addresses the extent of hydrogen loss attributable to biochemical reactions.