Compressed air energy storage (CAES) is one of the many energy storage options that can store electric energy in the form of potential energy (compressed air) and can be deployed near central power plants or distribution centers. In response to demand, the stored energy can be discharged by expanding the stored air with a turboexpander generator.
Analysis of compressed air energy storage systems is usually conducted by taking both compression and expansion stages into consideration using ideal gas laws. Expanders’ mechanical work is first transformed.
The number of sites available for compressed air energy storage is higher compared to those of pumped hydro [, ]. Porous rocks and cavern reservoirs are also ideal storage sites for CAES. Gas storage locations are capable of being used as sites for storage of compressed air .
Research has shown that isentropic efficiency for compressors as well as expanders are key determinants of the overall characteristics and efficiency of compressed air energy storage systems . Compressed air energy storage systems are sub divided into three categories: diabatic CAES systems, adiabatic CAES systems and isothermal CAES systems.
Appendix B presents an overview of the theoretical background on compressed air energy storage. Most compressed air energy storage systems addressed in literature are large-scale systems of above 100 MW which most of the time use depleted mines as the cavity to store the high pressure fluid.
However, due to the characteristics of compressed air storage system, the heating and cooling energy can not be constantly produced. So the system needs to be improved to meet the continuous heating / cooling requirements of users.