With the exploitation of resources such as coal, ore, and natural gases, numerous Abandoned Mine Underground Spaces (AMUS) have been left behind. To optimize the utilization of AMUS and promote environmentally friendly mining practices, this study investigates the feasibility of utilizing compressed air storage within these spaces. A mathematical model is formulated for this purpose, evaluating two compressed air storage technologies: conventional compressed air energy storage (CAES) and combined pumped hydro and compressed air storage (PHCAS). The study compares and assesses these technologies based on temperature patterns, energy storage levels, and potential safety concerns within the AMUS under various operational conditions. The findings reveal significant temperature fluctuations within the AMUS, with CAES showing temperatures exceeding 200°C during the charging process, while PHCAS demonstrates temperatures dropping below 0°C during discharge. These temperature differentials highlight potential risks during the recycling process, necessitating thorough evaluation tailored to specific AMUS conditions. Furthermore, CAES exhibits a higher energy storage capacity ranging from 11 to 86 MJ·m-3, surpassing PHCAS with an energy storage capacity of less than 5 MJ·m-3. However, PHCAS boasts a reduced contact area between the stored air and the surrounding environment, minimizing the risk of leakage compared to CAES. Consequently, assessing the potential risks of utilizing AMUS as storage caverns for CAES and PHCAS systems requires comprehensive analysis, considering factors such as storage capacity, permeability, gas leakage, and surrounding rock stability.

Compressed air energy storage,Abandoned mines,Pumped Hydro,Rock stability,Risk assessment,Economics