Thermodynamic analysis of a novel adiabatic compressed air energy storage system with water cycle

A novel water cycle compressed air energy storage system (WC-CAES) is proposed to improve the energy storage density (ESD) and round trip efficiency (RTE) of A-CAES. The new system decreases electricity consumption by recovering and reusing the hydraulic pressure of water. The thermodynamic characteristics of WC-CAES are evaluated by energy and advanced exergy analysis method. When the air storage pressure of WC-CAES is equal to the minimum storage pressure of A-CAES (4.2 MPa), the ESD and generalized storage density increase by 5.85 % and 32.41 %, respectively. When the air storage pressure increases to the same level as A-CAES (7.2 MPa), ESD and generalized storage density increase by 112 % and 162 %, respectively. In addition, the RTE increases by 1.6 % when the air storage pressure is 4.2 MPa. WC-CAES is therefore verified to be an effective way to improve the performance of conventional A-CAES.