There is no precise estimate of the number of coal fires burning under the Earth’s surface at any given time, but anywhere that coal is present, fire may be as well. Coal fires may arise spontaneously, or be ignited by lightning strikes, forest fires, or human activity. Once fire takes hold in a coal seam, it may burn for tens or even hundreds of years, slowly chewing its way through the fuel underground.
China, which supplies 75 percent of its rapidly increasing energy needs with coal, has the worst coal seam fires in the world. Spread out in a wide band across the continent, they devour 10 to 200 million metric tons of coal each year, and exhale it into the atmosphere in the form of sulfur dioxide, nitrogen oxide, carbon dioxide, mercury, arsenic, fluorine and selenium. The compounds contribute to air pollution, acid rain and global warming, and cause respiratory and other illnesses, as well as neurological and developmental problems in animals (including humans).
Not only do coal seam fires contribute to air pollution, they also create a risk of sink holes and landslides. As the coal underneath the surface burns away, the upper layers of rock and earth may collapse into the resulting cavities, as seen in the photo above.
In the autonomous region of Inner Mongolia, which produces the majority of China’s coal, one of these fires predates the coal mines by a century. The remaining fires, however, have been burning since the 1960s. The Chinese government calls them “natural coal fires,” but many are the result of dangerous or illegal mining practices. According to Dr. Anupma Prakash of the Department of Geology and Geophysics at the University of Alaska Fairbanks, “mining produces a lot of coal dust and carbonaceous rubble. This is much more prone to spontaneous combustion than a thick coal seam.”
The regional government of Inner Mongolia has recently announced plans to extinguish more than 60 fires in seven coal fields, at an annual cost of 200 million yuan ($29.3 million). Says Jianzhong Zhang of the German Aerospace Centre, which has collaborated with the International Institute for Geo-information, Science and Earth Observation (ITC) on coal fire research in the area: “If Inner Mongolia invests 200 million yuan, another 400 million can be expected from the central government. That will be enough to put out almost all the fires in Inner Mongolia.” The government’s plan calls for coal to be excavated around the fires, and then for sand, slurry and other materials to be pumped into the mines to smother the flames.
Similar measures have been successful at other coal fields in the area. Until recently, though, only coal seam fires that threatened active mines were of any concern. In 2002, Li Xiang, the chief engineer at Baijigou Mine, told the Telegraph: “If a fire does not affect our normal production, it will not be targeted.” Wang Jun, a fire engineer at the Ningxia Coal Industry Management Bureau, explained: “Our first priority is protecting mine production. Our second is preserving natural resources. Our third priority is protecting the environment.”
As China has come under increasing international pressure to control air pollution, however, it has begun to show more interest in controlling these fires. In June 2010, Ya Saning, head of Inner Mongolia’s Economic and Information Commission, said: “More than 20 million tons of coal is wasted every year in our region due to the smoldering fires. And the fires also cause serious air pollution.”
Just how serious China’s air pollution problems are became clear in the lead-up to the 2008 Olympics, when Ethiopian runner Haile Gebrselassie refused to compete in the marathon for fear of permanently damaging his asthmatic lungs. In the same period, an American researcher, Steven Q. Andrews, accused the Chinese government of manipulating air pollution figures, and claiming to have extinguished a coal seam fire in the western province of Xinxiang that was, in fact, still burning.
Not all of China’s air pollution comes from coal seam fires, but if Inner Mongolia’s efforts are successful, asthmatics like Mr. Gebrselassie may soon be able to breathe more easily.
My thanks to Dr. Anupma Prakash for permission to use her photos of coal fires in the Ruqigou coalfield in the Ningxia Hui Autonomous Region.