Assessment of H2 diffusivity in water and brine for underground storage: A molecular dynamics approach

H Kerkache and H Hoang and TKN Nguyen and A Geoffroy-Neveux and C Nieto- Draghi and P Cézac and S Chabab and G Galliéro, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, 128, 279-290 (2025).

DOI: 10.1016/j.ijhydene.2025.04.157

Hydrogen (H2) is poised to play a key role in the future energy landscape, but its efficient storage remains a challenge due to its small size and high mobility. Underground hydrogen storage in aquifers offers potential, yet risks arise from H2 diffusivity in brine, which can lead to migration or chemical reactions. In this study, H2 diffusivity in water and NaCl brine is studied using Equilibrium and Non-Equilibrium Molecular Dynamics simulations. A detailed benchmarking of force fields for H2, water, and Na+/Cl-ions is performed to ensure accuracy and reliability. These results provide diffusivity data for H2 across a broad range of underground conditions (298 K-473 K, 1-1000 bar, 0-6 mol/kg NaCl), analyzed within an excess entropy framework and modeled using the Stokes-Einstein relationship and an Arrhenius-type equation, offering a framework for predicting H2 diffusion behavior in water and brine in various conditions.

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