Research progress of isothermal compressed air energy storage system and technology

Decarbonizing the electricity sector is crucial for achieving the carbon peaking and carbon neutrality goals. Renewable energy sources, such as wind and solar power, can progressively replace fossil fuels (coal, natural gas, etc). While, long-duration energy storage technologies are required to reconcile renewable energy output with electricity demand. Compressed air energy storage (CAES) is an effective solution for this mismatch, thereby enabling a high penetration of renewable energy. As a vital part of CAES, isothermal compressed air energy storage (ICAES) features a high round-trip efficiency (RTE), demonstrating tremendous application prospects in future power systems. This study reviews recent advances in ICAES technology, which primarily includes spray injection technology and liquid piston (LP) technology. The operating principles and system configurations of the ICAES technologies are briefly introduced. Furthermore, a comprehensive review is presented from the perspectives of theoretical research, experimental studies and demonstrations. These isothermal technologies are compared and discussed in terms of technology maturity, power capacity, and round-trip efficiency. Additionally, these studies on key components are reviewed, including isothermal compressors, expanders, and air storage devices. Finally, the research methods for heat transfer characteristics and the heat transfer enhancement mechanisms are discussed. This study provides a comprehensive reference for the optimization of ICAES systems and key components, and proposes suggestions for future research and development to promote commercial application.