World's Largest Salt-Cavern Compressed-Air Storage: Huaneng Jintan's Two 350 MW Units Complete Integrated Start
Two 350 MW non-supplementary-fired units at Jintan completed an integrated start on 12 September, using the phase-one caverns a kilometre underground as the commissioning store.
On 12 September 2026, the two units of Huaneng's Jintan 2×350 MW salt-cavern compressed-air energy storage phase-two project completed an integrated start at Jintan, Changzhou, Jiangsu. Total installed capacity is 700 MW, design storage duration is eight hours, and the project states that 100% of its core equipment is domestically supplied (1).
What was actually started
The commissioning was carried out on the real storage condition. According to China Huaneng, the test reused the salt-cavern cavities built for phase one — roughly one kilometre underground — and verified coordinated operation of the compressor, the expander, the thermal storage and heat exchange system, and the control system. Vibration, temperature and pressure parameters during the start were all better than design values. The company states the next step is the full pre-grid-connection test and system commissioning programme (1).
The construction contractor's account gives the sequence in more detail. For unit 2, the team completed installation, stress-free piping, single-machine trial running, system purging, interlock testing and logic review, then brought the A-line and B-line compressor trains up together — described as four machines started in one attempt — followed by eight continuous hours of air injection into the phase-one cavern, a roll to 3,000 rpm and speed holding on the turbine-generator, and the full generator electrical test set (2).
The compression train
Shenyang Blower Works (ShenGu) supplied the compressors for phase two, as it did for phase one. The company states it provided axial and single-shaft centrifugal compressors with the complete system scope, and that the project builds its compression cluster from multiple compressor trains in series and parallel (3). The earlier notice that phase two had started construction records the same scope (4).
Xiangtan Electric supplied eight large brushless-excitation synchronous motors to ShenGu as the drive equipment for the compressor trains, in three frame sizes, TDWKS33-2, TBPDWKS34.5-2 and TDWKS41.5-2. The company describes the duty as frequent start-stop, high efficiency and long life, suited to a storage plant operating on variable load (5).
Dongfang Electric's Dongfang Steam Turbine works supplied the turbine-generator side: a 350 MW air turbine-generator set on a single shaft with triple reheat and multiple cylinders, described as configured for frequent grid peak-shaving duty (6).
The thermal side
The compression heat is not discharged. The project's thermal storage system uses sixteen hot-water tanks of 3,500 m³ each, a total of 56,000 m³. The tanks are pressurised, which raises the boiling point of the stored water from 100 °C to 180 °C (7).
The plant is non-supplementary-fired. The phase-one plant at the same site was the world's first non-supplementary-fired compressed-air energy storage station and entered commercial operation in May 2022; it has since run continuously for more than 1,500 days, has taken part in more than 960 grid peak-shaving events, and has delivered more than 650 GWh of peak-shaving energy (7).
Design figures and the wider build-out
Phase two is designed for eight hours of charging and four hours of discharge, with about 330 charge-discharge cycles a year; one charge stores 2.8 GWh (2). One industry account puts the system's energy conversion efficiency above 70% (8).
By the end of the first quarter of 2026, compressed-air energy storage under construction in China exceeded 5 GW, with more than 36 GW at the planning stage (7). Among the other projects named in the same account: the Huaian salt-cavern plant, with two 300 MW units and 2,400 MWh of storage, entered full operation in January 2026; the Feicheng 300 MW advanced compressed-air energy storage demonstration station first connected to grid in April 2024; and the 300 MW artificial-cavern station at Yumen is under construction (7).
What the source does not state
Huaneng's release does not give the plant's round-trip efficiency, the date of grid connection or of commercial operation, the number of compressors in each train, the compressor discharge pressure, or the motor rating. The salt-cavern storage volume, the discharge pressure at the wellhead and the cavern operating pressure range are not stated in the commissioning releases. The tender or contract value for the compressor scope is not published. The phase-two release does not state whether any equipment item is supplied from outside China.
Where this connects on this site
- Compressed-Air Energy Storage: What the Compressor Train Has to Do
- Diaphragm vs Piston vs Screw Compressors: A Comparison Table
Sources
| # | Basis |
|---|---|
| 1 | Jintan phase-two integrated start on 12 September 2026; two units; total 700 MW; design storage duration 8 hours; core equipment 100% domestically supplied; commissioning on the real storage condition reusing the phase-one salt-cavern cavities at about 1,000 m; coordination of compressor, expander, thermal storage and control system verified; vibration, temperature and pressure better than design values; next steps are pre-grid-connection testing and system commissioning — China Huaneng official release, "世界最大盐穴压缩空气储能项目机组启动", https://www.chng.com.cn/detail_jtyw/-/article/ccgb60va5Gwc/v/1324459.html |
| 2 | A-line and B-line compressor trains started as four machines in one attempt; eight continuous hours of air injection into the phase-one cavern; turbine-generator rolled to 3,000 rpm and held; full generator electrical tests; 8-hour storage and 4-hour discharge; about 330 cycles a year; 2.8 GWh stored per charge — PowerChina (中国电建) account of Shandong Electric Power Construction No. 1 Company's scope, "央视报道：世界最大盐穴压缩空气储能项目完成整组启动", https://www.powerchina.cn/zxzx/mtjj/art/2026/art_f3225538a35245f4acf53ccc50d40681.html |
| 3 | ShenGu as compressor supplier with axial and single-shaft centrifugal compressors plus the integrated system scope, and the compression cluster built from multiple trains in series and parallel — 沈鼓集团官方平台 release carried with the CCTV report, source: 中国华能 / 央视网 |
| 4 | ShenGu's scope for Jintan phase two at project start, and phase one again — Xinhua Liaoning, 24 December 2024, http://www.ln.xinhuanet.com/20241224/288268fc1b0446d9b7d21e9bff566ac0/c.html |
| 5 | Eight large brushless-excitation synchronous motors delivered by Xiangtan Electric to ShenGu as compressor drive equipment, frame sizes TDWKS33-2, TBPDWKS34.5-2, TDWKS41.5-2 — 湘电集团 release, 14 September 2026, carried at https://www.jdzj.com/news/344125.html |
| 6 | Dongfang Steam Turbine 350 MW air turbine-generator set, single shaft, triple reheat, multi-cylinder, for frequent peak-shaving duty — 东方电气 official release, 14 September 2026 |
| 7 | Sixteen hot-water tanks of 3,500 m³, 56,000 m³ total, pressurised to raise the boiling point from 100 °C to 180 °C; phase one as the world's first non-supplementary-fired compressed-air energy storage station, commercial operation May 2022, over 1,500 days continuous running, over 960 peak-shaving events, over 650 GWh of peak-shaving energy; national build-out figures and the Huaian, Feicheng and Yumen projects — 中国能源网, "压缩空气储能：往地下千米'存'电的超级充电宝", https://www.china5e.com/news/news-1209218-1.html |
| 8 | System energy conversion efficiency above 70% — 中国能源产业发展网, "地下充电宝的国产化：江苏盐穴压储从60MW到700MW，二十年磨一剑", 18 September 2026, https://www.ccedia.com/finance_detail/23504.html |