Thermal performance of high-temperature isobaric compressed air energy storage

Compressed air energy storage is considered one of the most promising large scale energy storage technologies due to its advantages of large scale, high efficiency and long service life. Isobaric system, compared to isochoric system, can effectively improve the energy density of the system. Therefore, this paper proposes an isobaric system with water compensation. The thermodynamic model of the system is established, and it is used to analyze the effects of molten salt low temperature, compressor polytropic efficiency, turbine polytropic efficiency, gas storage pressure and depth on the system performance. The analysis results show that within a certain range, increasing the molten salt low temperature, compressor polytropic efficiency, and turbine polytropic efficiency can effectively improve the round-trip efficiency of the system. Moreover, the deeper the underground depth, the higher the round-trip efficiency and energy density of the system. The increase in gas storage pressure can enable the system to achieve a higher energy density.