A 660 MW/3.96 GWh advanced CAES project in China’s Henan province has entered the EPC tendering stage, marking another large-scale deployment of long-duration energy storage technology in the country.
The Jiyuan 660 MW advanced compressed air energy storage demonstration project published its EPC tender notice on August 18, according to the project document. The facility will be built in Sili town, Jiyuan, some 750 kilometers southwest of Beijing, with a planned static investment of approximately CNY 4.79 billion ($670 million). The project is expected to have a construction period of 36 months.
The project is being developed by Jiyuan Hengdong Energy Storage Technology and will include engineering, procurement, and construction works under a single EPC contract. The bidding deadline is Sept. 22, 2026.
Unlike conventional compressed air energy storage systems, which require external heat sources such as natural gas combustion during electricity generation, the Jiyuan project will adopt an advanced adiabatic compressed air energy storage (AA-CAES) configuration.
In an AA-CAES system, electricity is used to compress air and store it underground. The heat generated during compression is captured and stored in a thermal storage system, then reused when the compressed air expands through turbines to generate electricity. This approach eliminates fossil fuel consumption and improves system efficiency compared with traditional CAES technologies.
The project will use pressurized water as the thermal storage medium and construct a new underground cavern for compressed air storage. This differs from projects such as the 300 MW/1.8 GWh CAES facility in Feicheng, Shandong province, which used existing salt cavern resources.
Underground storage is a key factor in CAES economics. Salt caverns provide naturally sealed and cost-effective storage space but are geographically limited. Artificial rock caverns, such as the system planned in Jiyuan, can expand deployment possibilities in regions without suitable salt formations, although they require additional excavation and sealing work.
China has accelerated the development of advanced CAES in recent years as it seeks alternatives to conventional batteries for multi-hour energy storage. Representative projects include the 100 MW Zhangjiakou CAES demonstration facility in Hebei, the 300 MW/1.8 GWh Feicheng project in Shandong, and several 300 MW to 660 MW projects currently under construction or development in Henan.
With a six-hour storage duration, the Jiyuan project reflects China’s effort to scale compressed air storage from pilot demonstrations toward utility-scale applications. However, challenges remain, including the complexity of underground engineering, lower round-trip efficiency than lithium-ion batteries, and the need for appropriate market mechanisms to support long-duration storage assets.
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