Coal fires deep under ground are fuelling world's air pollution

Extensive fires burning underground in many coal-producing countries are stoking a little-known "global catastrophe", scientists warned as reported by Financial Times on Saturday.

These largely hidden blazes are a key ingredient of air pollution, particularly in Asia, and contribute significantly to global warming.

The world's coal-fire experts, who met at the American Association for the Advancement of Science conference, said new data from heat-sensing satellites and ground-based geological surveys showed the problem was much more serious than environmental scientists had realised. Thousands of fires are burning in the world's coalfields - and there is no easy way to put them out.

In China, the leading coal-producing nation, underground fires are believed to consume up to 200m tons of coal yearly, said Glenn Stracher of East Georgia College. That would release as much carbon dioxide as all the road vehicles in the US - equivalent to 2-3 per cent of carbon dioxide emissions from global combustion of fossil fuels.

Coal seams near the surface occasionally catch fire naturally - the right combination of sunlight and oxygen can cause spontaneous combustion, or the coal may be ignited by heat from forest fires started by lightning.

But most burning results from human activity, particularly mining. Once started fires may smoulder for decades or even centuries.

The most notorious US coal fire started in a mine close to Centralia, Pennsylvania, in 1962. The town was abandoned in the 1970s when pollution became intolerable - and the coal is still burning today. Last year a long-term coal mine fire near Glenwood Springs, Colorado, sparked a fire that destroyed 12,000 acres of forest.

Indonesia suffers a particularly destructive interaction between forest fires and coal burning, said Alfred Whitehouse, a US government expert seconded to the Indonesian government. Fires started deliberately to clear forest for farming have ignited coal seams close to the surface, which can in turn start more forest fires.

As a result, some of Indonesia's national parks - including a nature reserve used as a reintroduction site for orang-utans - are threatened. Of the 20,000 orang-utans estimated to remain in the wild, 15,000 are in the Kalimantan region now threatened by coal and forest fires. "Hundreds of orang-utans are sure to have been killed already," said Whitehouse.

"What went up in smoke in Indonesia makes it one of the worst polluters in the world," he added.

Most Indonesian coal fires have been relatively easy to extinguish, given sufficient resources, because they are close to the surface. A hundred had been put out by excavating the earth around the burning coal and pouring in water, Whitehouse said, but he estimated that 3,000 coal fires were still burning in Indonesia.

Gary Colaizzi, a US mining engineer, has invented a high-tech means of putting out coal fires. His company, Goodson and Associates, uses a heat-resistant grout - a mixture of sand, cement, ash, water and foam - that can be pumped around the burning coal and shut off its oxygen supply. Thus far the technique had extinguished 25 fires in the western US, he said. (*)