Thermodynamic analysis of a high temperature hybrid compressed air energy storage (HTH-CAES) system

The integration of energy storage with renewable sources is imperative as it mitigates the intermittency of the available energy. A novel high temperature hybrid compressed air energy storage (HTH-CAES) system design is presented as a viable solution, which has the benefit of eliminating the necessary combustion and emissions in conventional CAES plants. The hybrid configuration incorporates two stages of heating through separate low-temperature and high temperature thermal energy storage units. A thermodynamic analysis of the HTH-CAES system is presented along with parametric studies, which illustrate the importance of the operating pressure and thermal storage temperature on the performance of the storage system. Realistic isentropic component efficiencies and throttling losses were considered. Additionally, two extreme cavern conditions were analyzed and the cyclic behavior of an adiabatic cavern was investigated. An optimum operating pressure resulting in maximum roundtrip storage efficiency of the hybrid storage system is reported. The hybrid system was found to be more efficient and energy dense as compared with an advanced adiabatic design of the same power output.