The world's largest facility to turn excess methane gas from coal mines into electricity has been completed in North China's Shanxi Province, the Xinhua News Agency reported Friday.

The facility was completed by the Lu'an Group, which owns the Gaohe Coal Mine in the coal-rich province. The company said it would soon start operating the generator with a capacity of 30 megawatts, capable of utilizing 99 percent of methane gas discharged from the coal mine.

The poisonous gas is a common emission during underground mining.

Normally, mines will liquify the gas into methyl alcohol if it has a concentration higher than 30 percent, for concentrations between 10 percent and 20 percent it is captured and used to fuel internal combustion engines.

However, methane concentrations lower than 10 percent cannot be consumed through direct combustion.

Jia Jian, deputy head of the Methane Gas Research Institute of the company, said the new technology has helped tackle the problem of how to dispose of the waste.

He said by recovering and utilizing the gas, the project can help reduce 1.4 million tons of greenhouse gases and produce 200 million kilowatt-hours of electricity a year.

China's coal mines produce more than 10 billion cubic meters of low-­concentration methane gas each year, which causes greenhouse gas emissions equivalent to 200 million tons of carbon dioxide.

Jia said the project of making waste profitable has a good market potential.

The demonstration facility installed at Gaohe Coal Mine has drawn interest from a number of coal mining firms, which have signed agreements predicted to reduce 15.8 million tons of carbon emissions.

Coal mining firms in China are under greater pressure than ever to control carbon emissions as the government continues to step up efforts to cut emissions.

China has set an ambitious goal of reducing carbon emissions per unit of GDP by 40 to 45 percent from the level in 2005.