Progress in CO2 hydrate formation and feasibility analysis for cold thermal energy harvesting application

CO2 hydrate-based cooling applications are a novel scenario associated with rapid energy supply transitions, undoubtedly affecting carbon neutrality in energy conversion/storage and providing opportunities for cold thermal energy-harvesting applications. The inherent properties of CO2 hydrates allow for flexible changes in the phase-change conditions depending on the desired temperature or pressure range. In addition, its higher latent heat than that of ice can improve the industrial fields of phase-change utilization and comply to reduce CO2 in the atmosphere. CO2 hydrates can be successfully utilized in cold storage, cold thermal energy transportation, and cooling applications. Nevertheless, careful analysis must be conducted for this vast range of possible applications. Therefore, this study reviews the thermodynamics of CO2 hydrate, its kinetics, and the hydrate formation apparatus for cold thermal energy-harvesting applications. Various additives were compared and reviewed, and their effects on independent and mixed promoters are summarized. Three main methods for forming CO2 hydrates are analyzed, and the utilization of CO2 hydrates is thoroughly discussed. Furthermore, the feasibility and limitations of the different applications were evaluated. Consequently, the CO2 hydrate slurry cooling system has a high system efficiency with a coefficient of performance of 7.0, a 50% reduction in initial installation and maintenance costs, and a 70% reduction in CO2 emissions, enabling a clean and sustainable energy solution.