Compressed carbon dioxide energy storage system has the advantages of large energy storage density

compact system equipment and long operating life. Expander is the key equipment of the energy storage system and has a direct effect on the efficiency and performance of the entire energy storage system. This article reviews the research status of various types of expanders. The working principle and characteristics of different types of carbon dioxide expanders are introduced. The expander types that can be used in compressed CO2 energy storage systems are provided. The problems and their countermeasures of four kinds of expanders applied to energy storage systems were analyzed. The research direction of CO2 expander is pointed out

including design method optimization

key component structure optimization

leakage

sealing

friction

and lubrication

and so on

which provides reference for the optimal design of the expansion machine of compressed CO2 energy storage systems.