China’s Huaneng Jiangsu Branch has completed full start-up of the two main units at the second phase of the Huaneng Jintan salt cavern compressed air energy storage project, taking the facility’s total Phase II capacity to 700 MW.
The Phase II project has a designed storage duration of eight hours and uses naturally formed salt caverns around 1 km underground to store compressed air. Huaneng said the two units have now achieved stable operation, marking a major commissioning milestone for the large-scale storage facility.
During start-up, the project used the salt cavern developed during Phase I as a test facility. Engineers assessed the coordinated operation of the compressors, expanders, thermal energy storage and heat-exchange equipment, together with the plant’s control systems.
Huaneng said key operating parameters, including vibration, temperature and pressure, remained within design requirements during the tests. The next stage will involve pre-grid-connection checks followed by system integration testing.
The project is designed to absorb surplus electricity, including renewable generation, during periods of lower demand and return power to the grid during peak periods. Its eight-hour storage duration gives it a longer discharge capability than many lithium-ion battery projects, making it suited to shifting electricity across larger portions of the daily demand cycle.
The Jintan project is located in Jiangsu province in the Yangtze River Delta, a region with significant electricity demand and growing renewable generation. Huaneng said the facility will provide peak-shaving and rapid-response services while helping accommodate additional renewable power.
Salt cavern compressed-air storage uses underground cavities to contain compressed air. During charging, electricity drives compressors to inject air into the cavern. When electricity is required, the stored air is released through expansion equipment to generate power.
The completion of Phase II testing follows the development of the first phase at Jintan and provides further operating experience with large-capacity salt cavern storage. Once fully commissioned, the project is expected to contribute to grid balancing and renewable energy integration in eastern China.
