Potential Evaluation of Cross-Seasonal Heat Storage of Coal Mine Underground Reservoir: A Case Study Based on Multiphysics Coupling Numerical Simulation Method

This study explores the innovative use of post-mining subsurface voids by proposing a coal mine goaf-based underground reservoir energy storage system. By fully utilizing the geothermal potential and insulation properties of the mined-out coal seam, we established a finite element model considering the thermal-fluid coupling process to describe the seasonal energy storage process of the underground coal mine reservoir and analyzed the feasibility of achieving seasonal hot water storage through the underground reservoir, based on the model calculation results. By studying the temperature state of the hot water after the end of the heat storage process and the hot water output effect, the thermal energy storage and utilization potential of the underground reservoir were quantitatively analyzed using the factors of heat storage and heat production. The research results have clarified the feasibility of using coal mine underground reservoirs for cross-seasonal heat storage applications. The results of this study can provide new ideas for the utilization of coal mine goaf areas and underground goaf residual spaces and serve as a reference for the development and design of new energy storage facilities.