A new energy storage system was designed for use in closing coal mines, combining pumped-hydro and compressed-air methods. The system maintains constant air pressure and temperature, using flexible bags to store compressed air and reduce leakage. With a depth of 500m and volume of 10,000 cubic meters, the system can generate approximately 18 MW of power for 1.76 hours. This innovative system offers a practical way to utilize underground spaces in coal mines for renewable energy storage.