China’s innovative 1.2 GWh compressed air energy storage project

A state-led consortium is developing a 300 MW/1200 MWh compressed air energy storage (CAES) project in Xinyang, Henan province, featuring an entirely artificial underground cavern—China’s first of its kind.

The CNY 2.15 billion ($300 million) project, backed by local state-owned enterprise Xinyang Construction Investment Group, CAES technology specialist China Energy Storage National Engineering Research Center (China Energy Storage), and two other state investment firms, is set for completion by the end of 2026.

Unlike traditional CAES facilities that utilize natural underground formations or salt caverns, this project will excavate a dedicated storage chamber beneath a mountain over two years. The cavern, measuring 15 meters in diameter and 1,800 meters in length, will have a total air storage capacity of 318,000 cubic meters. Construction involves precision blasting, structural reinforcement, concrete lining, and a sealed steel layer to withstand an operating pressure of 14MPa.

The project is led by China Energy Storage’s Henan subsidiary, which has previously developed multiple CAES facilities, including 100 MW, 150 MW, and 300 MW installations. As of December 2024, approximately 400 meters of the transport tunnel had been completed, nearing 80% of target progress, with excavation of the storage cavern already underway.

Once operational, the facility is expected to achieve a conversion efficiency of 72.1% and generate 420 million kWh annually—enough to power 350,000 households. The system incorporates China Energy Storage’s latest 300 MW CAES technology, featuring multi-stage compressors, high-load turbines, and advanced supercritical heat exchangers.

This design improves efficiency by 2% over its 100MW predecessor while reducing unit costs by 30%. By replacing conventional CAES combustion chambers with high-efficiency heat exchangers, the system eliminates reliance on fossil fuels, ensuring zero emissions and environmental sustainability.

Designated as a pilot project under China’s National Energy Administration’s new energy storage initiative, the Xinyang facility pioneers an innovative air-sealing approach for artificial underground storage, offering a significant boost to the commercialization of CAES technology in China.