CHARACTERIZING MICROBIAL COMPOSITION IN GROUNDWATER TO UNDERSTAND THE IMPACT OF HYDROGEN LEAKAGE FROM UNDERGROUND HYDROGEN STORAGE (UHS) SYSTEMS

To diminish anthropogenic warming caused by fossil fuel energy sources, hydrogen has emerged as a promising energy carrier that could significantly reduce greenhouse gas emissions and promote sustainable energy systems. However, efficient and reliable hydrogen gas (H₂) storage in the subsurface remains a critical challenge, especially on a large scale. Specifically, underground hydrogen storage could potentially leak into a groundwater aquifer overlying a storage reservoir. Leakage of H₂ into groundwater can change the geochemistry as well as induce microbial driven processes. Microorganisms, such as sulfate-reducers, are naturally abundant in groundwater and consume H₂ to produce hydrogen sulfide (H₂S), which can contaminate the freshwater drinking groundwater and cause damage to infrastructure. Hydrogen leakage could also trigger microbial responsible for metal mobility, which also will impact the water quality. However, the kinetics of these reactions and true impact of hydrogen leakage in groundwater is still unknown. In this study, a time series hydrogen-groundwater experiments are conducted and the changes in fluid chemistry and headspace gas composition will be analyzed along with DNA sequencing results to understand the extent and kinetics of biogeochemical reactions that occur if hydrogen leaks into groundwater.

Groundwater sample was collected from a freshwater drinking groundwater well at an 80-foot depth in Fairmont, West Virginia. In the experiment, Ultra High Purity (UHP) hydrogen gas will be sampled and injected into six sealed glass vials with groundwater samples, representing six different days within a 16-day period. A sterile groundwater control and sterile DI water blank will also be analyzed. For each glass-sealed vial, 16S rRNA sequencing, IC and ICP-MS, and GC-TDS will be performed. The proposed experiments will provide insights into the rate at which microbial communities present in groundwater consume hydrogen, allowing us to reflect on the impacts of hydrogen leakage from underground hydrogen storage systems.