Adsorption and diffusion behavior of pure H<sub>2</sub>, and H<sub>2</sub>/CO<sub>2</sub>, H<sub>2</sub>/CH<sub>4</sub> mixtures in sandstone-rich clay shale reservoirs: Insights from molecular dynamics simulations
<p dir="ltr">Underground porous formations offer promising potential for hydrogen (H<sub>2</sub>) and carbon dioxide (CO<sub>2</sub>) storage, aiding the energy transition and decarbonization goals. Effective underground hydrogen storage (UHS) depends on selec...
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2025
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| Summary: | <p dir="ltr">Underground porous formations offer promising potential for hydrogen (H<sub>2</sub>) and carbon dioxide (CO<sub>2</sub>) storage, aiding the energy transition and decarbonization goals. Effective underground hydrogen storage (UHS) depends on selecting an appropriate cushion gas, typically CO<sub>2</sub> or methane (CH<sub>4</sub>), to control pressure, minimize H<sub>2</sub> loss, and enhance injectivity and productivity. This study uses molecular dynamics simulations to analyze the adsorption and diffusion behaviors of pure H<sub>2</sub> and H<sub>2</sub>/CH<sub>4</sub> and H<sub>2</sub>/CO<sub>2</sub> mixtures in slit nanopores of kaolinite and silica with different surface morphologies under subsurface conditions. Kaolinite exhibited the lowest H<sub>2</sub> diffusivity due to higher surface adsorption and interfacial gas density on its hydrophobic surface. In contrast, the Q<sup>2</sup> silica morphology (ionized with Na and OH) showed reduced interfacial density and adsorption, enabling higher H<sub>2</sub> diffusivity. CO<sub>2</sub> had the strongest surface affinity and served as a more effective diffusion barrier than CH<sub>4</sub> with 25 % cushion gas significantly reduced H<sub>2</sub> mobility. Overall, kaolinite-rich caprocks offer better sealing efficiency, while silica-rich formations (resembling Q<sup>4</sup> topology) may favor hydrogen accessibility and recovery during injection and production phases. These results underscore the influence of mineral type and cushion gas on hydrogen transport and confinement. Integrating these molecular-level insights with pore- and reservoir-scale models is essential for optimizing hydrogen recovery and ensuring long-term sealing in UHS operations.</p><h2>Other Information</h2><p dir="ltr">Published in: International Journal of Hydrogen Energy<br>License: <a href="http://creativecommons.org/licenses/by/4.0/" target="_blank">http://creativecommons.org/licenses/by/4.0/</a><br>See article on publisher's website: <a href="https://dx.doi.org/10.1016/j.ijhydene.2025.151214" target="_blank">https://dx.doi.org/10.1016/j.ijhydene.2025.151214</a></p> |
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