TAIYUAN, Jan. 2 -- 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 facility was completed by the Lu'an Group, which owns the Gaohe Coal Mine in the coal-rich province. The company announced on Tuesday 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, which qualifies 81 percent of the gas released during mining, can not 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 the project can decompose the gas into carbon dioxide and water under temperatures more than 950 Celsius, and use the heat and steam for power generation.

He said by recovering and utilizing the gas, the project can help reduce 1.4 million tonnes of greenhouse gases and produce 200 million kwh 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 tonnes 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 tonnes 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 gross domestic product (GDP) by 40 to 45 percent from the level in 2005.

By 2013, carbon emissions per unit of GDP dropped by 28.56 percent from 2005. In the first three quarters of this year, energy consumption per unit of GDP dropped by 4.6 percent from a year earlier and carbon emissions were down by 5 percent, data showed.