A comprehensive review of H2 physical behavior and H2-rock-microbial interactions in underground hydrogen storage

The global imperative to achieve carbon neutrality has significantly intensified research efforts toward large-scale underground hydrogen storage. Nevertheless, the efficient implementation of underground hydrogen storage systems faces substantial challenges due to physical and chemical losses of H2, as well as complex H2-rock-microbial interactions. A comprehensive understanding of these interactions, coupled with the development of robust H2 consumption assessment models, is therefore critically needed. This review systematically addresses the key physical and biochemical challenges in underground hydrogen storage, including H2 dissolution, adsorption, diffusion, capillary trapping, and H2-mineral-microbial interactions. From both experimental and simulation perspectives, the review critically analyzes the influence of critical factors such as temperature, pressure, saline electrolyte composition, rock mineralogy, and heterogeneous pore structures on the physical behavior of H2. Furthermore, the chemical characteristics of H2 are examined, with a focus on alterations to porous structures induced by H2-mineral reactions and pore blockage caused by hydrogenotrophic microorganisms. Existing models for characterizing the physical behavior of H2 and H2-rock-microbial interactions are evaluated, with an emphasis on their strengths and limitations. Additionally, the biological, mechanical, and seepage behaviors associated with the transport of multi-state hydrogenotrophic microorganisms, microfracture, and cyclic H2 storage are discussed. This review provides critical insights for refining characterization models of hydrogenotrophic microorganisms and improving H2 recovery rates in underground hydrogen storage. By advancing the understanding and optimization of underground hydrogen storage, this work contributes to the development of sustainable, carbon-neutral energy systems.