Direct use of simulated seawater achieving superior H2 gas uptake in H2-DIOX hydrates for offshore hydrate-based H2 storage

Hydrate-based H 2 storage has emerged as a promising solution for offshore wind-to-hydrogen applications. Seawater is widely accessible on offshore platforms and can be directly used as a hydrate former. However, effects of salt in seawater on the kinetics of hydrogen hydrate are less understood and warrants investigation. This study systematically examines the influence of NaCl on the H 2 hydrates formation in the presence of a thermodynamic promoter, 1,3-dioxolane (DIOX). Effects of NaCl on the thermodynamics, kinetics, and morphology of H 2 -DIOX hydrates were investigated. The thermodynamic inhibition on DIOX hydrates is more pronounced than that on H 2 -DIOX hydrates in simulated seawater, resulting in a slurry-like hydrate morphology that improves gas-liquid contact. H 2 final gas uptake achieved in simulated seawater is seven-fold that of pure water with H 2 only occupying 5 12 cages of sII hydrate. Our study provides insights into the direct use of seawater for offshore hydrate-based H 2 storage.