Coupled Utilization Technology of Thermal Energy and Compressed Air Energy Storage in Underground Space of Abandoned Mines: A Comprehensive Review

Deep underground space energy and resources have emerged as integral constituents of modern energy systems. China has more than 13 000 closed mines, which, thanks to their excellent sealing properties and thermal storage conditions, serve as ideal sites for compressed air energy storage (CAES) and geothermal development. However, CAES faces the issue of wasted compression heat, while geothermal development faces the risk of thermal depletion. Building on a summary of the principles, current status, and technical bottlenecks of CAES and geothermal utilization in closed mines, this paper proposes the synergistic development of CAES and geothermal energy to enhance efficiency. The compression heat generated during the energy storage phase is used to supplement geothermal heat, while geothermal heat is utilized to preheat air during the energy‐release phase, thereby improving overall efficiency. Taking the Pangzhuang Mine as an example, a development plan involving shallow extraction and medium‐to‐deep‐level gas storage was designed, with a CAES capacity of 134.3 MW and an efficiency of 60%; with total annual revenue of $14.25 million and a static payback period of approximately 5.3 years. This synergy improves the utilization efficiency of underground space and helps promote the low‐carbon transition of mining areas.