China endeavors to turn coal mine gas into clean energy source
Troubled by frequent coal mine accidents, China is learning from foreign experience to harness the fatal methane gas and turn the "No. 1 underground killer" into a new energy source.
The Pansan Coal Mine, located on the Huaihe River, has built dozens of bunker-shape structures under the high ventilating shaft. They are connected, through several bulky pipes, with two large gas tanks, which are linked to a small power plant.
Though the power plant's installed capacity is only 2,400 kilowatts in the first phase, it is one of the few plants using coal mine gas as energy source in China.
Wang Yuan, board chairman of Huainan Mining Group in Anhui Province, the owner of the mine, said they have solved the difficulty in extracting and gathering gas under complicated geological conditions by adopting various technologies of ground well drilling, level hole drilling, oblique cross hole drilling and multi-piping extraction.
Wang said that gas is now the main fuel for some 20,000 households in the mining area and has been used to generate electricity.
What is more important, he said, using gas has brought about safety and profits to the coal mine, with death toll rate per million tons of coal output decreasing by ten times in the past three years, while coal output increasing by three times.
Statistics from the State Administration of Coal Mine Safety show that more than 80 percent of the deaths from coal mine accidents are related to gas.
The direct economic losses brought by gas accidents amount to 750 million yuan (about 92.5 million US dollars) a year.
In order to ensure work safety for coal mines, China used to pump the gas out and discharge it.
As a result, hundreds of million cubic meters of coal mine gas is discharged to pollute the air. Once the ventilation system breaks down, the life security of the miners are greatly threatened, said Zhu Xun, president of China Mining Industry Federation.
"Some leading mining groups in China have well realized the problem and are seeking ways to handle it," Zhu said.
They learn from the foreign experience to collect the gas and use it as a fuel.
The calorific value of the coal mine gas is two to five times as much as that of the coal gas for home use and produces little pollution.
Zhu said it has the potentials to replace the natural gas as a kind of high-quality and clean energy source .
Statistics from China Mining Industry Federation say that the methane gas resource in China amounts to 31,460 billion cubic meters, nearly the same as that of its natural gas reserve.
Major mining enterprises including Pingdingshan of Henan Province in central China, Kailuan of Hebei Province in north China and Tiefa of Liaoning Province in northeast China are all making comprehensive use of mine gas under complicated conditions.
Yuan Liang, Head of the national group in charge of compiling "The Overall Plan for Coal Mine Gas Treatment and Utilization", said the central government is launching a national action of harnessing coal mine gas.
However, experts also say that compared with developed countries, China still has a long way to go in the utilization of coal mine gas.
The United States has a far less reserve of coal mine gas than China, but has utilized as much as 40 billion cubic meters of coalmine gas, which is widely used in fields of power generation, the chemical industry and automobile fuel.
Yuan said China should consider the coal mine gas as a substitute for natural gas, because the latter will be only enough for 30 to 50 years of exploitation.