Molten Chloride Salts for Thermal Energy Storage in Concentrated Solar Power Plants

Recently, more and more attention is paid on applications of molten chloride salts in concentrated solar power (CSP) plants as thermal energy storage (TES) and heat transfer fluid (HTF) materials due to their high thermal stability limits (>800°C) and low prices, compared to the commercial TES/HTF materials in CSP - nitrate salts (decomposed at ~550°C). Over the course of the SunShot Initiative, the U.S. Department of Energy (DOE) has supported the molten chloride salt development for the next generation CSP (Gen-3 CSP) [1]. A higher TES/HTF operating temperature in CSP leads to higher efficiency of thermal to electrical energy conversion of the power block. However this causes additional challenges, particularly increased corrosiveness of metallic alloys used as containers and structural materials. This presentation outlines our current development progress of molten chloride salts as TES/HTF materials in the next generation CSP [2-6], including in-depth investigation on corrosion behaviors and mechanisms of metallic alloys in molten chlorides at operating temperatures of 500-800°C, and development of corresponding corrosion mitigation strategies towards realization of commercial applications of molten chlorides in CSP