China's first geothermal supercritical carbon dioxide heat extraction project officially begins operation in Zhengzhou, Central China's Henan Province, May 19, 2026. (Photo/CCTV)

(ECNS) -- China's first geothermal supercritical carbon dioxide heat extraction project has officially begun operation in Zhengzhou, Central China's Henan Province, marking a new breakthrough in the efficient development and utilization of geothermal energy, according to China Huaneng Group Co. on Tuesday.

Unlike traditional geothermal heat extraction, the project uses supercritical carbon dioxide, or CO₂, as the heat transfer medium instead of water. The supercritical CO₂ is injected into the bottom of a geothermal well, where it absorbs underground heat before returning to the surface and transferring that heat to water used for heating.

Compared with traditional water-based geothermal heat transfer, supercritical CO₂ has higher density and lower flow resistance, enabling greater heat extraction efficiency. The technology can increase heat extraction capacity by about 20% while reducing energy consumption per unit of heating by 10%.

The process also avoids groundwater extraction, formation contamination and disturbance to the geological environment, ensuring cleaner and safer heat extraction.

Once fully operational, the project will be able to meet the centralized winter heating demand of more than 18,000 square meters of residential space, replacing about 288 tons of standard coal and reducing carbon dioxide emissions by around 750 tons each year, the company said.

(By Zhang Dongfang)