Review of Ionic Semiclathrate Hydrates as Thermal Energy Storage Materials: Properties and Applications

Thermal energy storage is an emerging technology that has addressed the energy crisis in various industries worldwide. Phase change materials (PCMs) are widely used in thermal energy storage. Ionic semiclathrate hydrates are outstanding PCMs in terms of their safety and energy storage capacity. This review highlights recent advancements in the fundamental and practical studies of hydrate-based thermal energy storage. We focused on air conditioning, battery cooling, and cold chains as typical applications of hydrates and classified the thermophysical properties of hydrates such as their equilibrium temperatures and dissociation enthalpies with respect to the applicable technologies. The correlation between the manifested thermophysical properties and the characteristics of the guest compounds is discussed based on reported data. The dynamical characteristics of hydrate slurries, including their rheological and crystal growth characteristics, were investigated to determine the flow conditions for the transportation of the slurries. Furthermore, this review summarizes the findings of heat transfer studies that explored the design and fabrication of energy storage devices using hydrates and provides future prospects for hydrate-based thermal energy storage.