https://j.people.com.cn/n3/2026/0520/c95952-20458345.html

China’s first geothermal project utilizing supercritical carbon dioxide (CO2)—developed and constructed by China Huaneng Group—officially commenced operations on May 19 in Zhengzhou, Henan Province. This project employs supercritical CO2 as a heat transfer medium instead of water. The system works by injecting supercritical CO2 down to the bottom of a geothermal well—reaching a depth of 2,500 meters—where it absorbs heat from the earth before being returned to the surface to transfer that thermal energy into water used for heating.

Compared to the water-based medium systems typically used in conventional geothermal applications, supercritical CO2 offers higher heat extraction efficiency due to its greater density and lower flow resistance. This results in an approximately 20% increase in heat extraction capacity and a 10% reduction in heating energy consumption per unit area. Furthermore, because the entire process involves no extraction of groundwater—thereby preventing aquifer contamination and minimizing disturbance to the geological environment—it enables a clean and safe method of heat extraction.

The system is capable of meeting the centralized heating demand for residential areas covering over 18,000 square meters during the winter season.