Volume 62

Study on the Performance of Hot Dry Rock Wellbore-Based Compressed Air Energy Storage System Xueling Liu, Jiapeng Wu, Bo Feng

Abstract

For CAES (Compressed Air Energy Storage) system, using underground wellbore as storage spaces for compressed air can utilize the heat of underground reservoirs, thus achieving the increase in the production temperature of the air during the energy release stage, thereby improving the efficiency of the system. In this study, a combined underground wellbore CAES and heating (W-CAESH) thermodynamic cycle is put forward, and the performance of this system is investigated. Based on the theory of local thermal equilibrium, the actual gas state equation, and thermodynamic theory, heat transfer in the reservoir and the thermo-dynamic cycle performance are simulated. First, the heat transfer between the compressed air and Hot Dry Rock (HDR) reservoir is investigated. Then the power generating and energy storage performance are analyzed. Finally, the overall performance of energy storage and heating is evaluated in different operating conditions. Results indicate that the Round-Trip Efficiency (RTE) of the wellbore CAES is 55.93–62.25%, which is increased 15~20% compared the conventional CAES systems. When heating load is considered, the overall efficiency of this system is about 96.17%–97.47% as mass flow rate varies between 10–20 kg/s, and the overall efficiency rises with compressed-air mass flow.

Keywords Compressed Air Energy Storage, Hot Dry Rock, Combined CAES and Heating, Round Trip Efficiency