Thermal Energy Storage Performance Metrics and Use in Thermal Energy Storage Design

This paper presents thermal energy storage (TES) modeling approach and performance evaluation. We are developing modeling tools that will allow evaluation of the performance of a TES system that integrates 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. We attempt to develop a general method based on efficiency metrics and a CSP integration scheme to facilitate various TES designs, and to be able to evaluate their performance in CSP plants. The paper will discuss TES performance metrics in terms of three efficiencies: first-law efficiency, second-law efficiency, and storage effectiveness. The paper uses the design metrics to size TES as an example to illustrate derivation of the efficiency values and application of the three efficiencies.