China's largest oil refiner, China Petrochemical Corporation (Sinopec), said on Wednesday that it has started drilling a geothermal well with about 5,000 meters in Haikou City, south China's Hainan Province.                  

The well will be the country's deepest geothermal well, said the Sinopec.

Geothermal energy is a thermal energy that exists in rock masses, fluids and magma bodies. It can be classified into three categories: shallow geothermal resources, hydrothermal and dry hot rock.

China has abundant geothermal resources, but the utilization of hot dry rock resources, with over 180 degrees Celsius in temperature and buried 3 to 10 kilometers underground, is still in the exploratory stage.

It is estimated that the amount of hot dry rock resources in China is equivalent to 856 trillion tonnes of standard coal, said Sinopec, citing data from the China Geological Survey, adding that it is equivalent to 3,200 times of the country's annual energy consumption in 2022, if only 2 percent of the resources can be recovered.