Efficient utilization of abandoned mines for isobaric compressed air energy storage

There are massive abandoned coalmines and corresponding underground space, which provides a viable solution to energy storage of renewable energy generation. Here a novel scheme of isobaric compressed air energy storage (CAES) is proposed to improve the performance of energy storage in underground space. Energy recovery efficiency and energy storage density of isobaric CAES are respectively 70.60 % and 5.74 kWh/m3, while they are 70.56 %, 1.14 kWh/m3 and 60.19 %, 2.46 kWh/m3 respectively for pumped hydro storage and isochoric CAES. Abandoned mining fields can install photovoltaic and wind power, while underground tunnels can storage energy, transforming abandoned mines into a renewable energy support base with electricity generation and storage integrated into a site. Electrical energy with low frequency and high frequency in the base can all be used by driving compressors and heaters respectively. Besides, isobaric CAES can provide space heating and cooling simultaneously through using interstage compression heat and expanding refrigeration technique.