Major CO2 power generator starts operations

The world's first commercial supercritical carbon dioxide power generator started operations in Southwest China's Guizhou province recently, a significant milestone in the global transition toward high-efficiency waste heat recovery, said its operator China National Nuclear Corp (CNNC).

Known as Chaotan One, the new generator, located at a plant in Guizhou's Liupanshui city, uses carbon dioxide instead of steam to transfer heat. Each unit of the project boasts a power generation capacity of 15 megawatts, it said.

It has been connected to the grid from a steel production plant in Guizhou to produce electricity from waste heat, addressing a long-standing technical bottleneck in the efficient utilization of small-to-medium scale thermal energy sources.

Huang Yanping, CNNC chief scientist and chief designer of Chaotan One, said the commercial operation of this project represents the first transition of this innovative technology from laboratory to commercial implementation worldwide.

The system, with simplified structural design and fewer components, makes it possible to operate and maintain more easily compared to conventional steam-cycle plants. It can generate over 70 million kilowatt-hours of electricity annually, adding about 30 million yuan ($4.26 million) in revenue.

By utilizing supercritical CO2 power generation, the project implements an innovative power cycle that is more efficient, takes up less space, requires fewer auxiliary components and reacts faster than traditional systems, he said.

According to Huang, when the working pressure of CO2 exceeds 73 atmospheres and the temperature exceeds 31 C, it enters a supercritical state, leading to increased density that approaches a liquid state, which enables it to store more energy.

Meanwhile, its viscosity remains very low, close to that of a gas, resulting in smaller flow resistance.

According to CNNC, the system offers a drastic performance leap over traditional sintering waste heat steam power technologies currently in use, with overall power generation efficiency up by more than 85 percent, net electricity generation improved by over 50 percent and required floor space reduced by 50 percent.

Beyond being an innovative technology, supercritical CO2 power generation is poised to significantly contribute to the country's dual-carbon goals by efficiently converting industrial waste heat into power, it said.

Industry experts believe the innovative thermoelectric conversion technology comes at a critical juncture for China's energy landscape, as the country's electricity consumption is expected to reach a record high in 2025, with total power use projected to surpass 10 trillion kWh nationwide.

Rising demand is driven in large part by high-tech and advanced manufacturing industries, according to the national energy work conference held recently in Beijing.

Power use in sectors such as new energy vehicle manufacturing and wind power equipment manufacturing has jumped more than 20 percent and 30 percent year-on-year, respectively, from January to November. Electricity consumption in the internet and related services sector surged more than 30 percent, it said.

Wang Hongzhi, head of the National Energy Administration, said at the conference that China is set to overfulfill its target of having nonfossil energy account for 20 percent of its total energy consumption in 2025.

Thanks to robust green investment, the leapfrog development of the new energy sector, and the accelerated construction of major hydropower and nuclear power projects, the country's green and low-carbon energy transition has accelerated this year, Wang said.

The Nuclear Power Institute of China started research into the world's cutting-edge supercritical CO2 power conversion technology as early as 2009. In 2023, construction commenced on its demonstration project in Liupanshui.

In 2024, CNNC launched a demonstration project integrating molten-salt energy storage and supercritical CO2 power generation technologies, with scheduled demonstration operations set for 2028.

Looking ahead, the supercritical CO2 power generation technology will be integrated with multiple heat sources to form power generation systems, said Huang.

This will help expand its applications to solar thermal power, waste heat recovery, energy storage and other fields, he said.

zhengxin@chinadaily.com.cn