Huaneng engineers in Zhengzhou have commissioned China's first commercial closed-loop geothermal demonstration project that circulates supercritical carbon dioxide rather than water. The well reaches a depth of 2,500 meters.
In the closed-loop design, CO2 is injected at approximately 8 degrees Celsius and returns to the surface at about 22 degrees Celsius after absorbing heat from the surrounding rock.
Using supercritical CO2 as the working fluid reduces the energy required for pumping by roughly 10% compared with water-based systems.
The same design change increases the heat-extraction capacity of the well by approximately 20%.
The project operates as a sealed circuit, meaning no fluid is withdrawn from or injected into the natural reservoir.
Huaneng has not disclosed the total thermal output of the demonstration well or a timeline for commercial scaling.
Independent verification of the reported efficiency gains has not been published.
The company describes the project as a step toward using the Earth as a rechargeable thermal battery for clean heating and power.
China's First Commercial Supercritical CO2 Closed-Loop Geothermal Project Turns the Earth into a Rechargeable Battery
This is an independent summary. The complete reporting, supporting context and any primary documents remain with Pandaily.