Optimized Salt Selection for Solar Thermal Latent Heat Energy Storage

Abstract For solar thermal power to be cost effective as a baseload generation paradigm, the cost and efficiency of every subsystem must be improved. To reduce the cost of thermal storage and increase the working temperature of the subsystems for greater efficiency, appropriate storage materials must be identified for study. Unfortunately, there is an enormous search space of salt mixtures that are suitable candidates for thermal storage and must be analyzed for cost effectiveness to determine which candidates are the best. To lessen the experimental burden, this article combines previously validated theories for estimating the properties of salt mixtures with an analytic design optimization method to better estimate the true cost of each candidate. Five hundred and sixty three binary, ternary, and quaternary mixtures are analyzed. Five mixtures are identified as the prime candidates for a cascaded latent heat thermal energy storage system for a supercritical CO₂ Brayton cycle generator. This system is cheaper than the Sunshot Initiative cost targets, bringing the solar thermal paradigm into cost competition with fossil fuels.