BIOGEOCHEMICAL MODELING OF UNDERGROUND HYDROGEN STORAGE IN ILLINOIS BASIN SANDSTONES

Hydrogen (H₂) is an energy carrier that provides an opportunity for the energy sector to accelerate large-scale decarbonization. When coupled with other renewable energy, H₂ serves as a battery analog through power-to-gas technology, where surplus electricity is used to produce H₂ gas via electrolysis. Then, the gas can be stored in the subsurface and recovered during high energy demand. H₂ has been successfully stored in salt caverns in the U.S. since the 1980s, however, the feasibility of H₂ underground storage in siliciclastic formations requires assessment. Recent findings indicate that injecting H₂ into a sandstone reservoir might trigger biogeochemical reactions that could consume H₂, leading to commodity and energy loss. Laboratory experimental studies show that the risk of H₂ loss due to abiotic geochemical reactions is negligible in sandstone reservoirs under 100℃; however, biotic geochemical reactions involving microbes (e.g., methanogens, acetogens, etc.) are likely to consume H₂ and generate byproducts under conditions amenable to microbial growth.

Here, we investigate the potential for reservoir biogeochemical reactions to consume H₂ through thermodynamic and kinetic modeling of two reservoirs in the Illinois Basin using the software, Geochemist’s Workbench (GWB). The studied reservoirs are depleted hydrocarbon reservoirs in the Aux Vases and Cypress Sandstones, which have been converted to underground natural gas storage facilities. Water chemistry, mineralogy, and reservoir parameters (e.g., temperature, pressure) used in this modeling were sourced from literature and available databases for the Illinois Basin. By using biogeochemical modeling, we initially assess (i.e., ahead of laboratory experiments) the extent to which H₂ may be consumed by microbial activity under reservoir conditions. Furthermore, we are evaluating the kinetics of H₂-consuming reactions to better determine the importance and rate of these reactions. Simulating H₂ reactivity in the subsurface provides insights into the viability and potential issues associated with utilizing candidate reservoirs for subsurface H₂ storage.