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Cleaner energy from coal mine methane

By Yu Tianyu (China Daily)
Updated: 2009-07-20 10:04

Coal mine methane might still be an unfamiliar phrase for the residents of Jincheng, a city in the coal-rich Shanxi province, but it has become a part of their daily lives.

Tian Xianping, 52, no longer struggles with cumbersome bottled gas each month in her home in the Shenyun neighborhood of Jincheng.

The neighborhood was equipped with coal mine methane pipelines in 2007.

"In the past, it would cost me about 80 yuan ($11.71) for bottled gas. The methane is cheap, convenient and clean," Tian said.

"We use about 20 cu m of methane a month and each cu m costs 0.48 yuan."

More than 1,000 households in the Shenyun neighborhood now enjoy the convenience and lower cost of methane gas.

The Jincheng East Glassware Co Ltd glassware plant uses coal mine methane, too.

Li Yuqing, the company's general manager, said the company invested 20 million yuan in 2008 to make the switch from coal-powered furnaces at the glassware plant.

The plant's four furnaces now use 3.9 million cu m of methane every year, saving 4,000 yuan per day with the switch from coal, Li said.

The benefits are more than just a matter of price, Li said.

"The heat utilization rate of burning gas is about 80 percent, compared to 60 percent with burning coal," he said.

"And the temperature is easier to control when using gas to power the furnaces, which is very crucial to improving the quality of glassware products," Li said.

Clean power

The production process is "cleaner", too, he added, which is better for the workers' health.

Over a year, the glassware plant can avoid using 8,350 tons of coal and thereby reduce consumption of 8,350 tons of coal and reduce carbon dioxide emissions by about 132 tons.

Unrecovered coal mine methane is about 21 times more potent than carbon dioxide -- a major contributor to global warming.

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Coal accounts for more than 70 percent of China's energy consumption, and Chinese coal mines release more than 6 billion cu m of methane each year.

Methane is highly explosive and must be drained during underground coal mining operations.

However, methane also is a high-quality, clean energy source when recovered.

Recovery takes place during mining operations or before the start of mining activities.

The recovered methane then is used as a clean fuel source for households and commercial and industrial enterprises, or for power generation.

Shanxi province is one of the richest coal mine methane recovery areas in the country.

Pilot project

The Coal Mine Methane Development Project (CMMDP) at Jincheng in the southern part of Shanxi province was initiated in 2005 as a coal mine methane development and utilization demonstration project.

The project has led to coal bed methane production and also coal mine methane production for a 120-megawatt plant serving Jincheng consumers.

The provincial authority invested about 2.2 billion yuan including $117 million loans by the Asian Development Bank (ADB) and $20 million loans by Japan Bank For International Cooperation (JBIC).

In 2007, the project recovered more than 2 billion cu m of methane in Shanxi province, accounting for 44 percent of the country's total amount of recovered methane.

Wen Shihua, vice general manager of Shanxi Jincheng Anthracite Coal Mining Group Co Ltd, which is one of the project's major partners, said the recovered gas has been converted to liquefied natural gas.

Wen said the gas now is being transported to the country's southern provinces, including Guangdong and Fujian provinces.

The liquified gas, with a methane content of 30 percent to 80 percent, can be used for power generation and industrial and household use, Wen said.

The project will also capture coal mine methane from other mines for distribution to residential, commercial and industrial consumers in the Jincheng area.

In Jincheng, more than 30,000 households already were cooking and heating their homes with coal mine methane by last year.

The project's goal is to ultimately serve 90,000 households and a variety of industries with a minimum of 166 cu m of coal mine methane each year.

Ultimately, the environmental benefit will be a reduction in carbon dioxide-equivalent emissions by at least 4.4 million tons a year.