Three-dimensional thermo-mechanical analysis of abandoned mine drifts for underground compressed air energy storage: A comparative study of two construction and plugging schemes

Abstract

Compressed air energy storage (CAES) is a large-scale energy storage technology that can overcome the intermittency and volatility of renewable energy sources, such as solar and wind energy. Although abandoned mines can be reused for underground CAES of large scale, their feasibility requires further investigations. This study performs a comparative study on the effects of two construction and plugging schemes on the thermo-mechanical responses of an abandoned drift for the 60-MW CAES project in Datong Yunggang Mine, China. The first scheme uses only the drift as the air container, and the shaft is plugged with concrete. The second scheme uses the drift and shaft. A coupled 3D model is established, and the interaction of the temperature field, displacement field, and air state is fully considered. The numerical model is validated via previous analytical and numerical methods. The simulations indicate that air temperature and air pressure evolve “up-down-down-up” in one CAES cycle. The two schemes have roughly consistent air temperature, and relative huge difference exists for the air pressure. During the charging stage, relatively high tensile stress is induced by the air injection into the caverns. The first scheme shows less stress concentration and lower tensile stress, indicating that the concrete plugging at the intersection between Drift 1080 and North-5 Shaft is effective to reduce the stress concentration. This study can serve as reference for CAES design in similar engineering and studies.