China links first commercial supercritical CO2 power generator to the grid

A grid milestone for a new kind of power cycle

China has connected the world’s first commercial power generator that runs on supercritical carbon dioxide to the electric grid, marking a new stage for high efficiency thermal power. The installation sits inside the Shougang Shuicheng Steel plant in Liupanshui, Guizhou, and converts high temperature waste heat from steel production into electricity. Built by the Nuclear Power Institute of China under the China National Nuclear Corporation with engineering support from Jigang International Engineering and Technology, the project comprises two units rated at 15 megawatts each. The working fluid is carbon dioxide, not steam, and the manufacturer says the units can capture and use waste heat at least 50 percent better than conventional steam based systems used in steel mills.

This matters because supercritical carbon dioxide, often shortened to sCO2, can enable smaller turbines, quicker startup, and higher thermal efficiency at high temperatures. Those traits match the needs of heavy industry, where heat that currently escapes through stacks and cooling systems can be turned into a stable source of power. The same traits also align with next generation nuclear reactors and concentrated solar power plants, where every percentage point of efficiency can lower costs and reduce the size of core components.

The Guizhou project is also a test of how this technology performs outside a lab. Steelmaking is one of the most energy intensive industries, and sintering lines and furnaces release large flows of heat at temperatures well above 700 Celsius (1292 Fahrenheit). Harvesting that heat improves the energy balance of the plant and can cut the local grid draw. It can also reduce water use compared to steam cycles, a benefit in regions where water supplies are tight.

What is supercritical CO2 power and why it matters

Supercritical carbon dioxide is carbon dioxide kept at a temperature and pressure above its critical point, roughly 31 Celsius and 74 bar. In this state it is a dense fluid with properties of both a gas and a liquid. That density lets engineers build compact turbines and heat exchangers. In an sCO2 power block, the fluid moves in a closed loop, absorbing heat from a source, expanding through a turbine to spin a generator, then rejecting heat to a cooler before being compressed and sent back to the heat source. The loop is known as a Brayton cycle, a cousin to the gas turbine cycles used in jet engines, but with CO2 as the working fluid and with recuperators that recycle heat within the loop.

How the cycle works

At the steel plant, hot gases from sintering and related processes pass through a heat exchanger that transfers energy into the sCO2 loop. The heated carbon dioxide expands across a turbine, turning a generator to produce electricity. After expansion, the CO2 still carries substantial heat, so it passes through a recuperator to preheat the incoming stream, improving efficiency. The fluid then sheds remaining heat to a cooler, is compressed, and returns to the heat exchanger to repeat the process. Because CO2 close to its critical point is easy to compress compared to a normal gas, the cycle spends less energy on compression, which helps raise net efficiency.

Efficiency and size advantages

Traditional steam Rankine cycles are mature and reliable, yet their efficiency plateaus without very high temperatures and pressures, and their components are large. Reports from the Chinese project and from international pilots indicate that sCO2 cycles operating at high temperatures can surpass 50 percent thermal efficiency, while modern steam cycles are nearer 40 percent in similar regimes. In waste heat applications the exact efficiency depends on the source temperature and equipment design, but the sCO2 approach offers a large step up in how much of that heat can be turned into power. The hardware is also compact because CO2 is much denser than steam, so turbines and piping can be much smaller at a given power level.

Why a steel mill provides the perfect heat source

Steel plants expend vast energy in sintering, coking, and hot rolling. Sintering agglomerates fine ores at temperatures that often exceed 700 Celsius. Furnaces and off gas channels then carry that heat out of the process. A supercritical CO2 loop can intercept this flow through a robust heat exchanger, reclaiming a large fraction of the energy that would otherwise be wasted.

There are added benefits in an industrial setting. An sCO2 power block uses very little water compared to steam systems, since there is no need for large volumes of boiler feedwater or wet cooling towers. CO2 as a working fluid is relatively inert and less corrosive to many alloys than high temperature steam, which can ease some materials challenges. The closed nature of the loop means the CO2 is not vented in normal operation. Small CO2 inventory losses can occur and must be managed, but the system does not rely on a steady supply of fresh CO2.

For a plant operator, these traits translate to a smaller footprint for the power block, reduced auxiliary equipment, and more flexible operation. Startup and shutdown can be quicker than with steam, which is useful for processes that change temperature through the day.

Could this scale to nuclear and solar power

Many advanced reactor designs produce outlet temperatures suited to sCO2 turbines. High temperature gas reactors, molten salt reactors, and sodium fast reactors all target hotter core temperatures than pressurized water reactors, and sCO2 can harvest that heat efficiently. A compact turbine also pairs well with small modular reactors where space and simplicity are priorities.

The same holds for concentrated solar power, which stores heat in molten salts and then runs it through a power block. A demonstration plan in China aims to retrofit a display scale solar tower plant at Dunhuang from steam to an sCO2 power block to assess supplier readiness and operating behavior. This effort highlights two essential components, a reliable molten salt to CO2 heat exchanger and a compressor train that can manage CO2 near the critical point. Both are demanding tasks, but progress in materials, seals, and control systems is bringing them within reach.

If heat exchangers and turbomachinery prove durable in real plants, the route to larger sCO2 power blocks becomes clearer. The gains are attractive, higher cycle efficiency means smaller solar fields or smaller reactor cores for the same grid output, and lower water use eases siting constraints.

How China built it and who is behind the project

The Guizhou installation is the product of a long running program at the Nuclear Power Institute of China, part of CNNC. The institute has worked on sCO2 loops, turbines, bearings, seals, and controls for over a decade, publishing component tests and building pilot rigs. Jigang International Engineering and Technology partnered on the engineering side for heavy industry integration. The host, Shougang Shuicheng Steel, provided the site and access to high grade waste heat streams.

Each unit is rated at 15 megawatts. Using two units creates redundancy and gives operators a chance to test control strategies under real production conditions. CNNC describes the project as a foundation for future units in heavy industry and power generation, with the goal of standardizing modules that can be replicated across sites. Replication is important, since the economic case for waste heat power grows when equipment can be produced at scale and installed with minimal customization.

What experts say

Outside China, research groups and industry teams have been steadily proving sCO2 components and subsystems. In Texas, the Supercritical Transformational Electric Power pilot plant, a 10 megawatt electrical facility backed by the U.S. Department of Energy and led by a consortium, completed its first phase in 2024 and demonstrated full speed operation with integrated turbomachinery and controls. Researchers at the Southwest Research Institute, which supports that program, stress the importance of integrated testing where compressors, turbines, heaters, coolers, and control software run together as a single plant.

Mark Hibbs, a senior fellow at the Carnegie Endowment for International Peace who studies the Chinese nuclear sector, said China is pressing ahead quickly to show technical leadership.

“The Chinese are moving very, very fast. They are very keen to show the world that their program is unstoppable.”

Tim Allison, who directs the Department of Machinery at the Southwest Research Institute and works on the Texas pilot, described the milestone of running an integrated sCO2 power block at speed.

“Operating the integrated system is a noteworthy accomplishment. It follows the team’s successful component based commissioning activities and demonstrates combined operation of all equipment, including plant controls, compressor, heat exchangers, heater, turbine and CO2 inventory in addition to the facility’s electrical and gas supply and cooling water systems.”

The engineering hurdles that still need solving

Building compact, high efficiency turbines that endure high temperatures and speeds is the central challenge. Academic and industrial studies describe turbine rotors spinning near 30,000 to 40,000 revolutions per minute, with blades and casings facing temperatures above 600 Celsius. Nickel based alloys and advanced steels are common materials for inner cylinders and rotors, while outer casings use ferritic steels to manage stress and cost. The right mix balances strength, corrosion resistance, and thermal expansion so that clearances remain tight without rubbing.

Seals and bearings are equally important. Dry gas seals limit leakage of CO2 at the shaft, and some designs explore gas bearings instead of oil bearings to simplify lubrication systems and avoid thermal issues. Research on a 25 megawatt class turbine found that arranging the balance piston within the cooling gas section cut rotor length, reduced leakage paths, and lowered mechanical losses. A more compact rotor improves stability and simplifies the housing. Another scheme that replaced oil bearings with gas bearings reduced shaft length further and removed the need for a separate cooling and lubricating system. These refinements help raise efficiency and reliability.

Control of the cycle during transients is another area of active work. Small scale demonstrations have shown that changes in pump speed, heat input, and load can produce overshoots in pressure and flow before the system stabilizes. Engineers map out combinations of mass flow, pressure ratio, and rotational speed to identify stable zones where maximum power and efficiency occur. A small sCO2 turbo generator test reached electric output in the tens of kilowatts with measured total efficiency near 59 percent under optimal conditions, illustrating both the promise and the fine control required.

Heat exchangers that move energy between dirty industrial gases and a clean CO2 loop must resist fouling and thermal stress. Recuperators inside the CO2 loop need compact, high surface area designs to recycle heat without large pressure drops. Compressors must operate efficiently near the CO2 critical point, where small temperature changes can swing density and impair performance if controls do not respond quickly.

Environmental and policy stakes

China has pledged to peak carbon emissions before 2030 and to reach carbon neutrality before 2060. Cleaning up the power that drives heavy industry is central to that plan. Waste heat recovery with sCO2 helps in two ways, it cuts the plant’s net electricity draw from fossil fired grids and it reduces water use in places where conventional steam cycles would need large cooling flows. For nuclear and solar thermal projects, higher efficiency directly lowers the cost of clean electricity.

Some analysts also point to a potential synergy with carbon capture. In principle, captured CO2 could supply the closed loop as a working fluid, offering a productive use for a portion of the gas. That said, a power cycle needs clean, dry CO2 to protect turbomachinery and minimize corrosion, and the loop is closed, so it does not steadily consume new CO2. Any integration with capture would focus on shared handling, storage, and purification steps rather than using CO2 as a feedstock that is burned or converted.

The new generator also speaks to resource constraints. Water savings can be large in arid regions where cooling water is scarce. A compact power block could fit on ships or in remote industrial sites, strengthening energy security by turning on site heat into on site power.

The global race and what comes next

Teams in the United States, Europe, and Asia are all advancing sCO2 component reliability and plant integration. The Texas STEP project moved from component commissioning to an integrated run and produced power during its first phase, building confidence that the technology can be scaled and repeated. China’s grid connected unit in Guizhou is the first commercial installation on an industrial process, and it will provide data on round the clock operation, maintenance cycles, and the economics of waste heat power in steelmaking.

From here, more units in steel and cement plants are likely if the performance claims hold up in monthly and yearly operation. Concentrated solar projects are evaluating sCO2 power blocks to shrink turbine halls and lift output. Advanced reactor designers plan for sCO2 as the default power conversion system, trading the bulk of steam plants for compact turbines and recuperators. Mobile nuclear sources for remote sites also benefit from compact equipment, and the density of CO2 helps keep turbine size small for a given power level.

The equipment supply chain will matter. High performance heat exchangers, dry gas seals, and high speed generators must be available from multiple vendors. Codes and standards for pressure vessels, piping, and seals in CO2 service will need to mature. Training operators to run and troubleshoot the cycle safely will be part of commercial rollout. A steady cadence of demonstration and replication can bring costs down and convince plant owners to adopt the technology at scale.

The Bottom Line

• China connected two 15 megawatt supercritical CO2 units to the grid at a steel plant in Liupanshui, Guizhou.
• The system uses waste heat from steel sintering to generate electricity and is described as at least 50 percent better at waste heat conversion than steam based setups.
• sCO2 cycles operate in a closed loop with CO2 above its critical point, enabling compact turbines and higher efficiency at high temperatures.
• The power block uses little water and can fit in tight spaces, which suits heavy industry, ships, and remote energy systems.
• Advanced reactors and concentrated solar plants are prime candidates for sCO2 power blocks because they deliver the high temperatures the cycle needs.
• Key engineering tasks include durable heat exchangers, efficient compressors near the critical point, and high speed turbines with robust seals and bearings.
• A U.S. pilot in Texas ran an integrated 10 megawatt electrical sCO2 plant and produced power during its first phase, showing progress outside China.
• China’s project provides the first commercial scale data on industrial waste heat to power using sCO2.
• Water savings and efficiency gains support China’s carbon peaking and carbon neutrality goals, while improving energy use in heavy industry.
• Scaling will depend on supplier readiness, operating reliability, and the economics of replication across multiple plants.