Thermodynamic analysis of the Chemical Looping Electricity Storage system incorporating an electric heater

Chemical Looping Electricity Storage system is a new energy storage approach with satisfactory thermal effi-ciency and high capacity density, especially when the material with high decomposition temperature is selected as the storage medium. In this study, two CLES systems, one using an electric heater directly, the other using a compressor and an electric heater, were investigated. A comprehensively analysis were performed from the perspectives of first and second laws of thermodynamics. The feasibility of the system configuration, as well as the round-trip efficiency and exergy destruction of each part under different operation temperatures were determined. Finally, the approaches to further improving the round-trip efficiency were discussed. Results show that for the CLES system using an electric heater and a compressor for heating, the increase in the charge temperature will increase the exergy destruction rate of the electric heater and reduce the round-trip efficiency. The operating temperature range and the round-trip efficiency can be improved by placing two reactor vessels in series for charge and parallel for discharge. For the CLES system direct heating with an electric heater, the ef-ficiency in the low temperature section is extremely low, and the exergy loss caused by heat removal during discharge can be up to 8.9 %. Multi-stage compression intercooling or isothermal compression can be used during discharge to reduce this loss and increase the round-trip efficiency by 8.2 %-16.3 %.

Automated summary

Chemical Looping Electricity Storage (CLES) system is a new energy storage approach that offers satisfactory thermal efficiency and high capacity density, particularly with a storage medium that has a high decomposition temperature. This study investigates two CLES systems using an electric heater directly or with a compressor and an electric heater. A comprehensive analysis based on the first and second laws of thermodynamics evaluates the feasibility, round-trip efficiency, and exergy destruction of each part under different operation temperatures. The approaches to enhance the round-trip efficiency are also discussed, focusing on the configuration and compression techniques.