Molecular simulation of hydrogen adsorption in subsurface systems with implications for underground storage

H Lee and TC Germann and MR Gross and M Mehana, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, 114, 71-80 (2025).

DOI: 10.1016/j.ijhydene.2025.02.451

This study explores hydrogen adsorption on mineral surfaces (pyrite, calcite, and quartz varieties) for potential storage in subsurface sites with these rock types. Grand Canonical Monte Carlo (GCMC) and Molecular Dynamics (MD) simulations are used to investigate the system across a range of temperatures, pressures, and pore sizes. The findings show that pore size significantly impacts hydrogen density, with nanopores facilitating higher adsorption due to stronger interactions with mineral surfaces. Temperature and surface chemistry also influence storage performance, with adsorption decreasing by 12-19% as temperatures rise. Pyrite, exhibiting weaker hydrogen-sulfur interactions, has the lowest adsorption capacity, while calcite and quartz, with stronger hydrogen- oxygen bonds, show higher capacities. Notably, non-hydroxylated Q4 quartz outperforms hydroxylated Q2 and Q3 in hydrogen storage. Additionally, isosteric heat of adsorption (Qst) analysis reveals that pyrite has significantly lower Qst values compared to calcite and quartz, indicating weaker hydrogen interactions. These findings provide insights into the role of mineral surface characteristics and temperature in optimizing hydrogen storage in geological formations.

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