Low hydrogen solubility in clay interlayers limits gas loss in hydrogen geological storage

Gas intercalation into clay interlayers may result in hydrogen loss in the geological storage of hydrogen; a phenomenon that has not been fully understood and quantified. Here we use metadynamics molecular simulations to calculate the free energy landscape of H-2 intercalation into montmorillonite interlayers and the H-2 solubility in the confined water; in comparison with results obtained for CO2. The results indicate that H-2 intercalation into hydrated interlayers is thermodynamically unfavorable while CO2 intercalation can be favorable. H-2 solubility in hydrated clay interlayers is in the same order of magnitude as that in bulk water and therefore no over-solubility effect due to nanoconfinement is observed - in striking contrast with CO2. These results indicate that H-2 loss and leakage through hydrated interlayers due to intercalation in a subsurface storage system, if any, is limited.

Automated summary

The intercalation of hydrogen into clay interlayers is thermodynamically unfavorable, unlike CO2 intercalation. The solubility of hydrogen in hydrated clay interlayers is similar to that in bulk water, indicating limited loss and leakage through intercalation in a subsurface storage system.