Investigation of a working fluid for cryogenic energy storage systems

Cryogenic energy storage (CES) systems are promising alternatives to existing electrical energy storage technologies such as a pumped hydroelectric storage (PHS) or compressed air energy storage (CAES). In CES systems, excess electrical energy is used to liquefy a cryogenic fluid. The liquid can be stored in large cryogenic tanks for a long time. When a demand for the electricity is high, the liquid cryogen is pumped to high pressure and then warmed in a heat exchanger using ambient temperature or an available waste heat source. The vaporized cryogen is then used to drive a turbine and generate the electricity. Most research on cryogenic energy storage focuses on liquid air energy storage, as atmospheric air is widely available and therefore it does not limit a location of the energy storage plant. Nevertheless, CES with other gases as the working fluids can exhibit a higher efficiency. In this research a performance analysis of simple CES systems with several working fluids was performed.