China Just Switched On the World's First Giant Carbon Dioxide Battery

On October 2, China connected the world's first 100-megawatt-class compressed carbon dioxide energy storage plant to the grid. The facility, developed by China Huadian in Mori Kazakh Autonomous County in Xinjiang, is the commercial debut of a technology that could change how power grids store electricity for hours at a time.

The 100 MW / 1,000 MWh installation sits in the Gobi Desert on a site of more than 840 mu, about 138 acres. Chinese state broadcaster CCTV described it as a giant "power bank" standing on the desert, charging during off-peak hours and discharging when demand peaks.

How a carbon dioxide battery works

The idea is simple, even if the engineering is not. When electricity is cheap and plentiful, usually overnight, surplus power runs compressors that squeeze carbon dioxide gas. The heat produced by compression is captured and stored, and the compressed gas is converted into liquid form for storage.

When demand rises, the process runs in reverse. The liquid CO2 is vaporized and expanded, and the expanding gas drives turbines that generate electricity for the grid. The system is closed loop: the same carbon dioxide cycles between gas and liquid states, and the operator reports zero carbon emissions throughout the process.

The hardware list shows the scale. The plant is configured with five gas storage chambers, 141 liquid storage units, and 97 thermal storage units, plus compression, heat exchange, and expansion power generation units.

The engineering, procurement, and construction contract went to Dongfang Electric, which developed the core equipment domestically: CO2 compressors, motors, turbine expanders, generators, pressure storage tanks, large heat exchangers, and high-power frequency converters. The plant uses what the company calls non-supplementary combustion gas-liquid phase change storage, meaning no extra fuel is burned to make the cycle work. The system is designed for rapid response to grid dispatch, flexible start-stop operation, and a wide load regulation range.

The numbers behind it

According to project details reported by CCTV News, the facility can store around 290 million kilowatt-hours of electricity per year during off-peak periods and discharge about 180 million kilowatt-hours during peak demand. It can generate continuously for more than six hours, with a response time measured in minutes.

Once fully operational, the project is expected to generate roughly 200 million kWh per year, save about 50,000 tonnes of standard coal, and cut carbon dioxide emissions by around 170,000 tonnes annually.

It charges on cheap nighttime electricity and pays it back when the grid is straining, using nothing but carbon dioxide, steel, and desert.

The engineering specs are striking. The turbine efficiency exceeds 90 percent, with an inlet flow rate of 1,472.4 tonnes per hour. Project leader Ma Guojiang said the unit's designed efficiency makes it the most efficient carbon dioxide power generation unit in China today.

Why it matters: storage without special geology

The biggest selling point may be where this plant can be built, which is to say, almost anywhere. Pumped hydro storage needs mountains and elevation differences. Compressed air storage typically needs underground caverns. The CO2 system operates above ground and does not depend on specific geological conditions, which makes site selection far more flexible.

Ma put the case plainly: "Compressed carbon dioxide has a higher energy density and offers numerous advantages, including high efficiency, low cost, high safety and zero pollution."

Beijing is treating the project as nationally significant. It was selected for the fourth batch of the National Energy Administration's first-of-its-kind major technical equipment list, and it is a green low-carbon demonstration project of the National Development and Reform Commission. Dongfang Electric built the project under that contract.

Built for a wind and solar heavy grid

The plant is paired with 600 MW of wind power and 400 MW of solar power, which will help smooth output fluctuations and reduce curtailment, the wasteful practice of switching off renewables when the grid cannot absorb them. Its stated grid roles include peak shaving, valley filling, and frequency and voltage regulation.

That pairing points to the real story. As wind and solar take a larger share of China's electricity mix, the grid needs long-duration storage that can soak up midday solar and overnight wind, then release it across the evening peak. Lithium batteries handle short bursts well, but multi-hour storage at grid scale is still an open contest between technologies.

Compressed CO2 has now entered that contest with a working 100 MW plant. If the Gobi project performs as designed, expect more of these "power banks" rising on flat, empty land wherever grids need hours of backup.

There is reason to watch this space closely. Long-duration storage is the bottleneck for grids running heavily on wind and solar. Lithium-ion batteries are excellent for bursts of minutes to a couple of hours, but storing energy across many hours remains expensive, and the technologies competing for that role include pumped hydro, compressed air, and flow batteries. The Gobi plant's real test begins now, in daily operation, where efficiency, reliability, and cost per stored kilowatt-hour will decide whether compressed CO2 earns a permanent place in the mix.