China supercritical CO2 plant construction has begun in Shandong, combining a 50MW generating unit with 400MWh of molten-salt energy storage.
YANTAI: China supercritical CO2 plant construction is under way in Shandong province, where China Huaneng is building what is described as the world’s first utility-scale project combining supercritical carbon dioxide power generation with molten-salt energy storage. Construction began on September 16 at Huaneng’s Bajiao power station in Yantai.
Known as the Ruitan demonstration project, the development will initially feature a 50MW supercritical CO₂ generating unit alongside a 100MW/400MWh molten-salt thermal energy storage system. The storage system is designed to provide four hours of thermal storage capacity.
The project is expected to become operational in 2027 and forms part of a Chinese national science and technology programme focused on developing CO₂-based thermal battery technology.
How does the technology work?
The system is designed to store surplus electricity as heat when power demand is low. Electricity from the Bajiao site’s existing generating units can be used to heat molten salt, which retains that thermal energy until it is needed.
During periods of higher demand, the stored heat can then be used in the power-generation process.
Instead of relying on steam as the working fluid, the China supercritical CO2 plant will use carbon dioxide maintained in a supercritical state to drive its generating cycle. Supercritical CO₂ combines properties associated with gases and liquids and can circulate through compact power-generation equipment.
The project’s 50MW unit is planned to operate with a working-fluid temperature of around 550°C. Developers say the technology offers advantages including compact equipment, operational flexibility and potentially higher efficiency compared with conventional steam-based thermal cycles.
Why molten salt matters
Molten salt is already used for thermal energy storage because heat can be retained and released later when electricity is required. Combining that storage method with a supercritical CO₂ cycle could provide another way of shifting electricity generation from low-demand periods to peak hours.
That flexibility is increasingly important as power grids integrate larger quantities of variable renewable energy.
The project should not, however, be confused with the world’s first supercritical CO₂ generating system. China has previously demonstrated the technology. The Ruitan project’s distinction is the scale and integration of supercritical CO₂ generation with molten-salt storage.
If the demonstration performs as designed, the China supercritical CO2 plant could provide useful engineering data on whether this combination can be deployed more widely for large-scale thermal energy storage and flexible electricity generation.
Impact to expect
Innovation. The project could help demonstrate whether molten-salt storage and compact supercritical CO₂ generation can work together effectively at utility scale, potentially offering grids another option for storing surplus energy and supplying electricity during peak demand.
