General Performance Metrics and Applications to Evaluate Various Thermal Energy Storage Technologies

The solution proposed in this paper presents a new modeling approach that integrates a generalized thermal storage performance model into a concentrating solar power (CSP) plant. The overall performance, including round trip efficiency, for a thermal energy storage system is highly dependent on the operating parameters and operation strategy of the complete power plant. Previous methods used for analysis of thermal storage have followed one of two approaches: The first requires time-intensive customized detailed performance models of the thermal storage system and the power cycle to account for the effects of charging and discharging storage on conversion efficiency and heat transfer fluid (HTF) return temperature to the solar field. The second method uses a simple energy balance with "derate" factors that do not accurately predict the effects of storage on other plant components. In this paper, we develop a generalized method based on efficiency metrics and discuss the application in TES sizing and performance evaluation for an early concept study. The method is an integral approach and complements the detailed models that simulate yearly operation of a CSP plant.