Molecular insights into hydrogen intercalation with carbon dioxide and methane in hydrated clay: Implications for hydrogen geo-storage seal integrity

T Muther and AK Dahaghi, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, 110, 386-400 (2024).

DOI: 10.1016/j.ijhydene.2025.02.217

Hydrogen is a promising clean energy solution, but its storage in geological formations presents challenges, including potential interactions with clay minerals that can lead to swelling and affect caprock integrity. This study investigates H2 intercalation in hydrated clays using Molecular Dynamics (MD) and Grand Canonical Monte Carlo (GCMC) simulations across realistic geological conditions, with pressures from 1 MPa to 50 MPa and temperatures from 298 K to 403 K. The research also explores the H2 intercalation in mixed systems including H2-CO2 and H2-CH4 mixture. The results indicated that the intercalation of H2 under various thermodynamic conditions and different basal/interlayer spacings was relatively low, making it unfavorable for intercalation into the hydrated region. In addition, the pressure generally increased H2 intercalation, but temperature had a complex effect, enhancing intercalation at low pressures due to H2 mobility, and reducing it at high pressures due to desorption. Furthermore, hydration states in clay influenced H2 intercalation, with low levels at 1W, increasing through the transition zone, and slightly decreasing at the stable 2W state, though still higher than 1W. Furthermore, the inclusion of CO2 and CH4 as the mixed components in H2 reduced H2 intercalation by 32% and 52% respectively. These findings will help identify potential leakage risks, ensure caprock integrity, and improve hydrogen storage efficiency, contributing to the safe and effective use of hydrogen as a sustainable energy solution.

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