Review and prospects of hydrate cold storage technology

Hydrate cold storage technology has been intensively researched in recent years and plays an important role in the macro-control of energy. This paper reviews the diversity and variability of hydrate cold storage media and the new hydrate cold storage system. The diversity is embodied by the types of hydrate cold storage media, which include alkane hydrates, freon hydrates, CO2 hydrates, water-soluble organic hydrates, and mixed hydrates. In mixed hydrates, the different components in the mix media play different roles in the process of hydrate formation. The variability is reflected in the differences in the external environments (environmental compatibility: ozone depletion potential and global warming potential) and the multiple reinforcement methods of hydrate nucleation. The reinforcement methods including mechanical methods, external field functions, and additives (mainly surfactants, nanoparticles, porous materials, and thermodynamic accelerators) are compared and discussed for optimisation of the hydrate formation conditions. The operational characteristics and application advantages of the new cold storage systems with different hydrate media are summarised. The environmental impact, energy efficiency, life cycle assessment, and commercial and industrial possibilities of the hydrate cold storage system are discussed. Finally, this review provides a comprehensive outlook of hydrate cold storage from an application perspective.