China Breaks Ground on a Molten-Salt, Supercritical CO2 Plant
China has started building a hybrid plant that stores surplus power as molten salt and turns it back into electricity with a supercritical CO2 cycle instead of steam — a design with nuclear and even lunar…
China has begun construction on the Ruitan hybridized power and storage facility, which will bank surplus electricity as heat in molten salt and discharge it during peak demand through a supercritical carbon dioxide power cycle rather than a conventional steam turbine.
China has broken ground on a power station that does two unusual things at once: it stores surplus electricity as heat in molten salt, and it converts that heat back into power using supercritical carbon dioxide rather than steam. The Ruitan project, reported by OilPrice, is being built with two stated aims — cutting the energy that a grid throws away when generation exceeds demand, and steadying the local network when demand spikes.
That combination is worth pausing on. Thermal storage and CO2 turbomachinery have each been demonstrated separately. Marrying them in a single commercial-scale plant is the part that makes this a test case rather than a routine build.
Why Engineers Want to Retire the Steam Turbine
Almost every thermal power plant on Earth — coal, gas, nuclear, most concentrated solar — works the same way. Heat boils water, steam spins a turbine, the turbine spins a generator, and the steam is condensed back to water. The Rankine steam cycle has been refined for well over a century, and it is very good. It is also bulky, water-hungry and bumping against its efficiency ceiling.
A supercritical CO2 cycle replaces water with carbon dioxide held above its critical point, where it behaves neither quite as a liquid nor quite as a gas. In that state it is dense like a liquid but flows like a gas. The practical consequence is that the working fluid carries far more energy per unit of volume, so the turbine that extracts that energy can be dramatically smaller for the same output. Smaller turbomachinery means less steel, less concrete, a smaller building and — in principle — less capital per installed kilowatt.
The second consequence matters more for a grid balancer like Ruitan. Compact machines have less thermal mass, which means they can be brought up and down faster. A plant whose economic purpose is to sit idle and then deliver power into a demand peak lives or dies on how quickly and how often it can cycle without shredding its own components. Steam plants are poor at that; they were designed to run flat out.
Molten Salt Is the Cheap Half of the Equation
The storage side of the design is deliberately low-tech by comparison. Molten salt holds heat at high temperature in an insulated tank. It has been used commercially for years in concentrated solar plants, which need to keep generating after sunset. The salt itself is inexpensive, the tanks are inexpensive, and the technology does not degrade in the way electrochemical storage does with each charge and discharge.
That is the strategic point. Lithium-ion batteries are excellent at short-duration, fast-response grid services and expensive at long-duration bulk storage, because cost scales with the amount of energy stored. Thermal storage inverts that: adding hours of duration largely means adding tank volume. For a grid with growing volumes of wind and solar output that arrives when nobody needs it, cheap bulk hours are the missing piece.
Pairing salt tanks with a CO2 cycle addresses the traditional weakness of thermal storage — the round-trip losses on the way back to electricity. The higher the conversion efficiency of the discharge engine, the less of the stored energy is wasted on the return journey.
The Nuclear and Lunar Ambitions Behind the Design
The project is also framed as a technology demonstrator with reach well beyond one regional grid. Supercritical CO2 cycles are of direct interest to the nuclear industry, particularly for advanced reactor designs that operate at temperatures where steam becomes awkward. A reactor paired with a compact CO2 turbine could shrink the footprint of the power island — the non-nuclear half of a plant that often drives a surprising share of the total cost.
The project is also framed as a technology demonstrator with reach well beyond one regional grid.
The lunar angle is less whimsical than it sounds. Any off-world power system faces the same hard constraints: no water to spare, severe mass budgets on anything launched, and long dark periods that demand stored energy. A dense working fluid in a small turbine, charged by stored heat, is close to the only architecture that fits those limits. Terrestrial demonstrators are where that engineering has to be proven first.
The Commercial Question Nobody Has Answered Yet
Supercritical CO2 has been on the verge of commercialization for the better part of two decades. The obstacles are materials and seals. CO2 at high pressure and high temperature is corrosive and brutal on bearings and heat exchangers, and the components are not commodity items with deep supply chains behind them. Efficiency gains on paper evaporate quickly if a plant spends its life in maintenance.
What China is buying with Ruitan is operating data — the thing no simulation supplies. If the plant cycles reliably through thousands of charge-discharge events, the design becomes exportable and the supply chain for CO2 turbomachinery starts to thicken. If it does not, the learning still accrues domestically.
Investors looking for a pure-play exposure will not find one easily. The equipment sits inside large industrial conglomerates, state-owned power groups and turbine manufacturers, where a demonstration plant is a rounding error on revenue. The more useful read is directional: the engineering race in grid-scale storage is broadening beyond batteries, and thermal routes are getting serious capital.
The Market Backdrop
The news landed on a soft session for U.S. equities. At the last close on Wednesday, 23 September 2026, the S&P 500 tracker SPY finished at $767.81, down 0.72% from the prior close of $773.38, having traded between $766.50 and $773.05. The Nasdaq 100 proxy QQQ closed at $741.21, off 0.84%, and the Dow tracker DIA ended at $514.30, down 0.71% — a broad, orderly step back rather than a sector-specific move.
What to Watch From Here
Three things will tell you whether Ruitan is a template or a one-off. First, the disclosed round-trip efficiency once the plant is commissioned — the share of stored energy that actually comes back out as electricity. Second, the cycling record: how many deep charge-discharge events the turbomachinery absorbs before major maintenance. Third, whether Chinese reactor developers commit to a CO2 power island on a licensed design, which would be the clearest signal that the technology has cleared its reliability hurdle.
For grid operators everywhere facing the same problem — too much renewable output at the wrong hours, too little dispatchable capacity at the right ones — the answer to those three questions matters a good deal more than the groundbreaking ceremony did.
Key facts
- Project: Ruitan hybridized power and storage facility, China — construction under way
- Storage medium: Molten salt, charged with surplus electricity as heat
- Generation cycle: Supercritical CO2 rather than a conventional steam turbine
- Market at last close: SPY $767.81 (-0.72%), QQQ $741.21 (-0.84%), DIA $514.30 (-0.71%), as of 23 Sep 2026 20:00 GMT
Frequently asked questions
What is a supercritical CO2 power cycle?
It is a way of generating electricity that uses carbon dioxide held above its critical point as the working fluid instead of steam. In that state the CO2 is dense like a liquid but flows like a gas, so it carries more energy per unit of volume. That allows a much smaller turbine to produce the same power output as a far larger steam machine.
How does molten salt store electricity?
Surplus electricity is used to heat salt until it melts, and the hot salt is kept in an insulated tank. The energy is stored as heat rather than as charge. When power is needed, the heat is drawn back out and run through a generating cycle. The salt is cheap and does not degrade with repeated charging the way batteries do.
What is the Ruitan project trying to achieve?
According to the project's stated goals, it aims to limit energy waste by capturing electricity that would otherwise be curtailed, and to stabilize the local power grid by discharging that stored energy during peak demand periods. It combines molten-salt thermal storage with a supercritical carbon dioxide generating system in one facility.
Why is this technology relevant to nuclear power?
Advanced reactor designs often operate at temperatures where steam systems become cumbersome. A supercritical CO2 turbine is far more compact, which could shrink the size and cost of the conventional power-generating half of a nuclear plant. Proving the turbomachinery at commercial scale on a non-nuclear project reduces the engineering risk for reactor developers.
Why does anyone mention the moon in connection with this?
Off-world power systems face constraints that suit this architecture: no water to spare for a steam cycle, strict limits on launch mass, and long periods of darkness that require stored energy. A compact turbine running on a dense working fluid, charged from stored heat, fits those constraints better than conventional alternatives.
How does thermal storage compare with lithium-ion batteries?
Batteries excel at short-duration, fast-response grid services but get expensive as duration increases, since cost scales with stored energy. Thermal storage works the other way: adding hours mostly means adding tank volume, which is comparatively cheap. The trade-off is conversion losses when heat is turned back into electricity, which is why the efficiency of the discharge engine matters so much.
