Electrochemical energy storage systems for solar thermal applications

Existing and advanced electrochemical storage and inversion/conversion systems that may be used with terrestrial solar-thermal power systems are evaluated. The status, cost and performance of existing storage systems are assessed, and the cost, performance, and availability of advanced systems are projected. A prime consideration is the cost of delivered energy from plants utilizing electrochemical storage. Three broad areas are addressed: (1) the electrochemical, or battery, component of the storage system; (2) the balance of system, or all components other than the battery; and (3) the overall solar-thermal plant with electrochemical storage. Included in the latter area is a tabulation of the levelized costs of delivered energy from complete plants with sixteen different, advanced electrochemical systems. This tabulation ranks the systems in order of economic attractiveness. The results of the study indicate that the five most attractive electrochemical storage systems are the: iron-chromium redox (NASA LeRC), zinc-bromine (Exxon), sodium-sulfur (Ford), sodium-sulfur (Dow), and zinc-chlorine (EDA).