http://en.people.cn/n3/2025/0110/c90000-20264443.html

A compressed air energy storage (CAES) power station utilizing two underground salt caverns in Yingcheng City, central China’s Hubei Province, was connected to the grid at full capacity. The project utilizes the caverns of an abandoned salt mine, about 500 meters deep, as its gas storage facility. This approach creates a super “power bank” with a single unit power output of up to 300 MW and a storage capacity of 1,500 MWh. The system conversion efficiency is about 70 percent, according to China Energy Digital Technology Group Co., Ltd., one of the project’s major investors.

This power station can store energy for eight hours and release energy for five hours every day. It generates an annual average of approximately 500 million kilowatt-hours of electricity, which can meet the annual power demand of 750,000 residents, according to the company. The Institute of Rock and Soil Mechanics (IRSM) of the Chinese Academy of Sciences (CAS) provided technical support for the underground energy storage system of the project.

The principle of CAES in salt caverns is similar to that of conventional pumped storage power plants. During periods of low electricity demand, electrical energy is used to compress air and store it in underground salt caverns. The compressed air can then be released during periods of peak demand to generate electricity.

Deep underground gas storage is the key to CAES projects. The concept will be applied to other CAES power plants currently under construction or planned in provinces including Hunan, Henan, Jiangsu, Jiangxi, Yunnan, Shaanxi and Shandong, with a cumulative power output of 1,950 MW, according to IRSM.