Hydrates for cold energy storage and transport: A review

Abstract

The energy demand for space cooling has more than tripled for the past thirty years and was responsible for emissions of about 1 Gt CO2 annually. The ever-increasing energy demand for cooling has posed a demanding question on improving the energy efficiency of cooling processes. On the other hand, with the growing global demand on LNG, cold energy released from LNG terminals has been growing to a historical high at 6.6 × 1014 kJ in 2017. Thus, there is a strong need to search for a suitable phase change material (PCM) best utilizing the cold energy released from the production sectors for storage and transport to the needed sectors. Among all the PCMs, semiclathrate hydrates (SCHs) with a suitable phase change temperature (5–27 °C) and high latent heat (190–220 kJ/kg) stand out as one promising candidate (a) to store and transport the cold energy and (b) to improve the energy efficiency of the cooling processes synergistically. In this review, we focus on reviewing SCHs as a cold energy storage and transport PCM covering both its fundamental properties (thermophysical properties, kinetics of formation and dissociation, rheological and transport properties, and safety and economic aspects) and its novel applications in several cooling processes. Prospects and challenges are also delineated on commercializing SCHs as a key technology enabler for the cold energy industry. There is strong confidence that possible disruptive SCH-based cooling technologies could be developed in the near future for energy efficiency improvement and environmental sustainability. © 2021