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

Abstract

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.

Crystal Growth of Clathrate Hydrate Formed with Carbon Dioxide and Deuterium Oxide: Implications for Hydrate-based Tritium Separation

“…Clathrate hydrates (henceforth called hydrates) are crystalline inclusion solids comprising a hydrogen-bonded lattice of host water molecules that encapsulates guest molecules . Hydrates can be employed in various technologies by using their unique characteristics. − For instance, utilizing the guest selectivity of hydrates, hydrate-based desalination has been actively investigated as low-energy, zero-emission water production technology to replace conventional reverse osmosis systems. − Another example is the hydrate-based molecular storage of ozone, which is the only technology that enables long-term high-concentration ozone preservation for sanitization purposes. − …”

Forum: Pathways toward Critical Advances in the Chemistry of Materials for Thermal Energy Storage

“…In contrast, inorganic salt hydrates and ionic semiclathrate hydrates represent promising nonflammable classes of PCMs with melting points in a critical temperature range for building and cold chain climate control (0 to 40 °C). Matsuura et al review ionic semiclathrate hydrates which are crystalline materials composed of water molecules and complex anions in cages around atomic or polyatomic cations . They break these compounds into temperature ranges appropriate for cold chain (−2 to 8 °C), building energy management (8 to 32 °C), and battery thermal management (25 to 45 °C) and correlate the phase equilibrium temperature, dissociation enthalpy, and guest–water and water–water molecular interactions with the type and mass fraction of the guest ions.…”