China completes 700 MW salt-cavern CAES project

China Huaneng finished full-system startup of its 700 MW Jintan salt-cavern compressed air energy storage project in September 2026, the largest such facility globally by installed capacity.

China Huaneng completed full-system startup of two 350 MW units at the Jintan salt-cavern CAES project in Changzhou, Jiangsu province on September 12, 2026. The 700 MW Phase II facility—developed jointly with China Salt Group and supported by Tsinghua University—uses four underground salt caverns (1,000 meters deep) with 1.2 million cubic meters of gas storage capacity. It achieves 2.8 GWh of electricity per charging cycle and 924 GWh annual generation, operating at 70% round-trip efficiency. The system includes 16 thermal storage tanks (56,000 cubic meters total) that reach 180°C, enabling peak shifting and grid-balancing for renewable energy. This project scales up from a 60 MW pilot commissioned in 2022.

The facility’s thermal storage design—using pressurized water at high temperatures—supports long-duration grid services without direct cost data. Its capacity makes it the largest salt-cavern CAES facility globally as of October 2026, though it does not claim to be the first 700 MW project. The system completes 330 charge-discharge cycles annually, providing critical stability for renewable integration.

This advancement moves energy security by enabling more reliable renewable grid support in China’s power system. While it doesn’t reduce energy costs yet, the project demonstrates scalable long-duration storage that addresses grid friction from intermittent renewables. Key watch points include whether the 2026 completion date reflects actual operational readiness (per source’s noted potential typo) and how thermal storage efficiency impacts real-world grid resilience beyond the current 70% benchmark.

*Note: All figures and specifications derive directly from the pv magazine report dated October 5, 2026. The source does not confirm cost-effectiveness or quantify storage duration beyond operational cycles.*

Source: pv magazine