Review on the challenges of salt phase change materials for energy storage in concentrated solar power facilities

Concentrated Solar Thermal Power has an advantage over other renewable technologies because it can provide 24-hour power availability through its integration with a thermal energy storage system. Phase change materials in the form of eutectic salt mixtures show great promise as a potential thermal energy storage medium. These salts are typically low cost, have a large energy storage density, are easily sourced/abundant and their use has a low environmental impact. Implementing molten salts as part of a thermal energy storage system, however, comes with some unique challenges. There are significant engineering design and material compatibility hurdles that need to be overcome and have made prototyping such a storage system difficult. This review summarises new advancements in phase change material research, a comparison analysis of salts and other storage technologies, and recommendations for future work required to address these challenges. Topics of interest include the latest simulation/modeling work for shell-and-tube and encapsulated storage configurations, corrosion degradation studies, and innovative optimization investigations from a larger power plant perspective. From the overall findings presented, if impurity levels can be stringently controlled in conjunction with better salt selection and better fidelity modeling studies, the prototyping of an effective commercial-scale storage system is feasible. Even though this technology is still in its infancy stage, salt phase change materials are a promising solution to the energy storage problem.