InterPore2025

Biogeochemical Reactions in Hydrogen Storage Salt Caverns: Sulfate Reduction in the Salado Formation

19 May 2025, 15:05

1h 30m

Poster Presentation (MS23) Advances in Experimental, Computational, and Analytical Approaches for Underground Hydrogen Storage Poster

Speaker

Atefeh Esfandiari (Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin)

Description

Hydrogen storage in salt caverns offers a promising solution for large-scale energy storage; however, biogeochemical reactions involving hydrogen, minerals, and microbial communities can compromise hydrogen quality. The Salado Formation, a salt cavern located in west Texas and southeastern New Mexico, is composed of evaporites such as halite and interbedded potash salts like polyhalite, providing a unique geochemical environment for these interactions. This research focuses on sulfate reduction as the dominant microbial process in the Salado Formation, supported by ion analysis of core samples and Gibbs free energy calculations. Microbial activity in hydrogen storage caverns poses three key risks: i) economic losses due to hydrogen consumption and sulfate-induced corrosion, ii) health and safety hazards from hydrogen sulfide generation, and iii) increased purification requirements upon hydrogen withdrawal. To study these impacts, sulfate-reducing bacteria were isolated from coastal sediment near the Gulf of Mexico to ensure compatibility with the high-salinity brine of the Salado Formation. The bacteria were cultured in a brine solution modeled after Permian seawater in Salado Formation prior to evaporation, with sulfate serving as the electron acceptor and hydrogen as the electron donor during multiple cultivation cycles. Once a high population of sulfate-reducing bacteria was established, DNA extraction and 16S amplicon sequencing were performed to identify the microbial strains. The isolated sulfate-reducing bacteria were subsequently used in experiments to evaluate their effects on hydrogen storage. Experiments were conducted in sealed, anoxic serum bottles containing the modeled brine and isolated bacteria, under conditions representative of hydrogen storage salt caverns. Cores from the Salado Formation, including halite, polyhalite, and anhydrite, were introduced to the experiments to study their impact on brine salinity and sulfate content, simulating realistic cavern environments. Gas composition in headspace was monitored using Gas Chromatography, while sulfate reduction was quantified via Ion Chromatography. Hydrogen sulfide, a key byproduct of sulfate reduction contributing to gas contamination, was measured using Gas Chromatography and colorimetric methods involving reagents and a plate reader. By examining factors such as hydrogen pressure, salinity, and mineral concentrations, and the presence of formation cores, this study aims to quantify the extent of microbial-induced hydrogen loss and gas contamination. These findings provide critical insights into the biogeochemical challenges of hydrogen storage in salt caverns and strategies to mitigate these risks.