Development and Application of HUST: A Hydrogen Underground Storage Screening and Ranking Tool Incorporating Operational Considerations, Geochemical and Microbial Reactions

Abstract Several attempts have been made to develop site selection criteria for underground hydrogen storage (UHS) in porous media (UHS-PM). Existing site selection criteria do not consider geochemical reactions and microbial interactions, which are critical processes in UHS-PM. The objective of this work is to share the development of a comprehensive UHS-PM site selection tool and its application in the Sacramento Basin. This work involved building an innovative open-source tool to optimize UHS site selection operations of the saline aquifers for subsurface hydrogen storage. This tool works on the principle of multi-stage screening based on UHS's hydrodynamics, operational, geochemical, and microbial perspectives. The multi-stage screening takes place in three stages. Stage 1 considers the productivity index as the main output and identifies the most important variables affecting hydrogen recovery. Stage 2 is built upon the screening criterion developed from the literature by identifying the conditions that lead to the losses of the injected hydrogen through geochemical reactions. Stage 3 is based on processes that could lead to losses based on the possible presence of microbes. The workflow also has the option to consider the weightage of each physical process, which leads to a more rigorous approach to UHS site selection. The site selection was applied to saline aquifers in Sacramento Basin. Results showed that applying only hydrodynamic considerations could lead to the wrong choice of a storage site because such a site, even with high permeability and porosity, could lead to losses due to geochemical reactions and microbial interactions. By including the weighting factors and reactions, the site that ranked highest was one that could allow sufficient storage of hydrogen, have a reasonable productivity index, while minimizing loss due to geochemical and microbial reactions. The novelty of this work lies in developing a site selection approach that considers the geochemical and microbial interactions when ranking sites for UHS. Such a workflow will close a significant gap in site selection because geochemical and microbial reactions are essential aspects of UHS-PM.