Development of molten chloride salts for thermal energy storage in next generation concentrated solar power (CSP) plants

Abstract

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 salt mixtures (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. A higher TES/HTF operating temperature leads to higher efficiency of thermal to electrical energy conversion of the power block in CSP, however causes additional challenges, particularly increased corrosiveness of metallic alloys used as containers and structural materials. This presentation presents corrosion behaviors and mechanisms of metallic alloys in molten chlorides at operating temperatures (500-800°C), as well as corresponding corrosion mitigation strategies to realize the commercial applications of molten chlorides in CSP, based on our works in these fields.