China has connected the world’s first commercial...

Editor's note: ...supercritical carbon dioxide (sCO₂) power generator to the grid at a steel plant, using high-pressure CO₂ instead of steam to convert waste heat into electricity with dramatically higher efficiency, simpler equipment, smaller size and potentially transformative impact on industrial and clean power generation worldwide. The significance of this engineering should not be overlooked because this sCO₂ system can generate about 50 percent more electricity from the same heat output from China's steel factories while achieving over 85 percent efficiency. This represents a "step-change improvement over conventional steam power" rather than an incremental upgrade. This means Chinese steel production can operate with around 85 percent greater efficiency, as waste heat is now converted into electricity that can be sold back to the grid. The US also has supercritical CO₂ (sCO₂) power technology, with active research, testing, and pilot systems developed by US national labs, the Department of Energy, and firms like Southwest Research Institute, but the difference is that China has now deployed it first as a commercial, grid-connected scale, while US projects remain largely at demonstration or pilot stages.

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World's first commercial supercritical carbon dioxide power generator begins operation

The generator will convert waste heat from the steel plant into usable electricity.

By Ameya Paleja | December 22, 2025

Chaotan One, the world's first commercial power generator that uses supercritical carbon dioxide (sCO2) instead of steam, has begun operations in China. This achievement breaks a century-old tradition of using steam for power generation, marking a major improvement in efficiency.

The invention of the steam engine was a first step towards the Industrial Revolution that changed the world. For the first time, humans could burn a fuel and use it to do work, not just produce heat.

Over the years, the engine's efficiency was further improved through different designs and fuels; however, the medium for doing work remained the same – steam.

Scientists seeking further improvements in power efficiency noticed that a significant portion of energy is wasted generating steam to drive turbines.

Water needs to be boiled first and needs to undergo a phase change to generate steam. Both steps are energy-intensive, and scientists have been looking for a better medium to replace them. They found this in sCO2.

What is sCO2?

Supercritical is a fluid state of CO2 gas where it is held above its critical temperature and pressure. We know that CO2 exists as a gas at room temperature and can be cooled to form dry ice by reducing pressure and lowering temperature.

However, when its temperature is raised to 87 °F (31 °C), and its pressure is increased to 1,070 psi (7.37 MPa), it enters its supercritical state.

In this state, CO2 exhibits properties of both a liquid and a gas. Release it into a container, and it will fill the space, but it will have the density of a liquid. In applications such as moving a turbine, this is extremely useful, since the gas-like state offers less resistance while the liquid-like state provides greater thrust.

Equally importantly, turning CO2 into its supercritical state is less energy-consuming than turning water into steam.

China and the US have been working to develop power generators that operate efficiently with sCO2. However, China has demonstrated its technical capabilities in this domain by deploying it in a commercial setting.

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