Characteristic Analysis of the Thermal Energy Storage Subsystem in Large-Scale TS-CAES System

Compressed Air Energy Storage (CAES) is one of the most promising technologies for addressing the intermittency and volatility of renewable energy power generation. Among them, Thermal Storage Compressed Air Energy Storage (TS-CAES) is equipped with a thermal energy storage (TES) subsystem, enabling the efficient recovery and utilization of compression heat. The performance of the TES subsystem has a significant impact on the overall performance of the large-scale TS-CAES system. Consequently, this paper analyses the characteristics of the TES subsystem, with a focus on its configuration and TES temperature. A comprehensive thermal-economic analysis indicates that a cascaded TES system combining molten salt and water represents the preferred configuration, exhibiting enhancements in round-trip efficiency (RTE) of 15.17% and 7.38% relative to water-based and oil-based TES systems, respectively, while also securing respective improvements of 55.82% and 22.90% in annual profit margin. It is also shown that a 5% increase in TES temperature leads to a maximum 3.14% improvement in RTE for the preferred system. This work provides theoretical guidance for developing large-scale, high-efficiency TS-CAES systems.