Gas hydrates and semiclathrate hydrates for H₂ and CH₄ storage: Kinetics, capacity and stability

Gas hydrates (or clathrates) have potential advantages as materials for hydrogen or methane storage with respect to other gas storage technologies. For example, hydrates can trap gases such as hydrogen close to ambient temperature, quite unlike porous materials where cryogenic temperatures are required. We show that substantial quantities of methane (around 45 v/v) can be stored reversibly in certain semi-clathrate hydrate structures at atmospheric pressure and ambient temperature, again in contrast to physisorption approaches. Several challenges exist: for example, the quantity of hydrogen stored in gas hydrates is well below the Department of Energy (DoE) target of 6 wt. %. By contrast, pure methane hydrate in "dry water" form stores 175 v/v gas: that is, very close to the corresponding DoE target. This presentation will discuss approaches to storing gases (H2 and CH4) in hydrated form, in particular strategies for accelerating hydrate formation kinetics, minimizing storage pressure (ideally to 1 atm), and maximising gas storage capacity.