Geologists have found large masses of hot dry rock (HDR), a form of clean energy, in northwest China's Qinghai Province, local authorities said on Monday.

The rocks, at least 150 square kilometers in area, were found 2,230 meters under Qiabuqia Township in Gonghe County, in the northern part of the Gonghe basin. It is the first time such a huge amount of HDR has been found in China.

The HDR is usually buried 3,000 to 10,000 meters under the earth's surface. It can be used to generate clean electricity through its high temperature.

The breakthrough was made by a China Geology Survey geothermal energy project, in partnership with Qinghai's department of land and resources. The project has been two years in the making.

Yan Weide, dean of the provincial institute of hydrological and geological engineering investigation, said HDR is effective in easing environmental problems caused by the greenhouse effect and acid rain.

The discovery will not only contribute to research on HDR, but could help China's regional energy restructuring process, said Wu Tingxiang, director of the Qinghai bureau of geology, mineral exploration and development.

The amount of HDR on the Chinese mainland is estimated to equal about 860 trillion tonnes of standard coal, 260,000 times that of China's current annual energy consumption.

Only a handful of countries have mastered the technology regarding power generation using HDR, including the United States, Japan and Sweden.