China has commenced construction on the world’s first utility-scale power plant combining supercritical carbon dioxide (sCO2) power generation with molten salt energy storage. The Ruitan demonstration project is located at China Huaneng’s Bajiao power station in Yantai, Shandong province, and is anticipated to begin operations in 2027.
The project aims to reduce energy waste and enhance grid stability by utilizing surplus electricity generated during periods of low demand. This excess electricity, primarily from the plant’s existing coal-fired units, will be used to heat molten salt stored on site. When electricity demand peaks, the stored heat will drive a supercritical unit that uses carbon dioxide instead of steam to generate electricity.
The initial phase of the development will include a 50-megawatt sCO2 power generation unit paired with a molten salt energy storage system rated at 100 MW and capable of storing 400 megawatt-hours of thermal energy. Unlike conventional thermal power plants that use steam to spin turbines, the sCO2 system operates the carbon dioxide at critical temperature and pressure levels, creating a dense fluid with properties of both gas and liquid. This fluid directly powers turbines and recirculates in a closed loop, which enables smaller plant sizes, eliminates water requirements, increases efficiency, and reduces carbon emissions. Additionally, these turbines can adjust output rapidly, with a ramp rate up to four times faster than traditional coal-fired units.
The heat source for sCO2 systems can vary and includes solar, geothermal, and industrial waste heat. Notably, China’s first commercial-scale sCO2 power generation unit, Chaotian One, began operations late last year in Guizhou province, utilizing waste heat from steel manufacturing.
Molten salt storage differs from battery energy storage in that it stores surplus energy as thermal energy rather than chemical energy. While batteries provide greater flexibility and mobility, molten salt systems offer cost-effective thermal storage solutions for large-scale energy projects, which can be reconverted to electricity or used for other heating applications.
The integration of molten salt storage with supercritical carbon dioxide power generation is gaining traction, with China National Nuclear Corporation targeting a project with this combined technology by 2028. Similar initiatives include the European Union’s SOLARSCO2OL project, which is developing a molten salt-driven sCO2 unit within a concentrated solar power plant.
Molten salt storage has also been incorporated into renewable energy projects such as the Dangsikong concentrated solar power plant under construction in Tibet. Scheduled for completion next year, this high-altitude facility will convert excess daytime solar energy into heat for use during peak periods, leveraging molten salt’s thermal storage capabilities.
The Ruitan demonstration represents a significant step in advancing flexible, efficient, and cleaner power generation technologies, with potential applications spanning from conventional thermal plants to future nuclear and renewable energy systems.