Molten Salts and Applications I: Molten Salt History, Types, Thermodynamic and Physical Properties, and Cost

Excess energy from solar, nuclear or coal power stations can be stored in molten salts (MS) in the 565 °C range. At elevated temperature, large containers can be used to store energy for up to a week and generate eight hours or more, depending on the container size, of electricity to be used at night or during peak demand hours. A stable diurnal energy supply is made available by energy storage and the fluctuation experienced at thermal solar power stations caused by weather conditions is reduced. Supported by Office of Naval Research (ONR), this paper presents a survey of molten salt properties used in solar power storage, as well as the history of molten salt usage for energy storage and production. The history of molten salt usage includes past, current, and future developments involving molten salt usage for nuclear and solar energy storage and production. Density, melting temperature, viscosity, electric conductivity, surface tension, and heat capacity of various molten salts are discussed. Since costs are important factor in selecting a molten salt compound, salts costs are presented. Recommendations are made regarding the efficient use of various types of molten salt.