The world’s largest facility to turn excess methane gas from coal mines into electricity has been completed in north China’s Shanxi Province, reports official Chinese news agency Xinhua. The facility was completed by the Lu’an Group, which owns the Gaohe coal mine in the coal-rich province. The company has announced that it will soon start operating the generator with a capacity of 30 MW, capable of utilising 99% of methane gas discharged from the coal mine.

The poisonous gas is a common emission during underground mining. Normally, mines will liquefy the gas into methyl alcohol if it has a concentration higher than 30%, and for concentrations between 10% and 20% it is captured and used to fuel internal combustion engines. However, methane concentrations lower than 10%, which qualifies 81% of the gas released during coal mining, 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 told Xinhua that the project can decompose the gas into carbon dioxide and water under temperatures more than 950°C, and use the heat and steam for power generation. He said by recovering and utilising the gas, the project can help reduce 1.4 Mt of greenhouse gases and produce 200 million kW/h of electricity a year.

China’s coal mines produce more than 10 billion m3 of low-concentration methane gas each year, which causes greenhouse gas emissions equivalent to 200 Mt of carbon dioxide. Jian 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 Mt 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% from the level in 2005.

By 2013, carbon emissions per unit of GDP dropped by 28.56% from 2005. In the first three quarters of 2014, energy consumption per unit of GDP dropped by 4.6% from a year earlier and carbon emissions were down by 5%, data showed.