Coal seam fires (and some natural gas fires)
are the forgotten environmental tragedy…

Above - A graphic view of a typical coal seam fire spewing a whole soup of toxic substances.

Due to the risks of coal fires, satellite pictures or thermal images have been used to map China's coal fires, which resulted in the discovery of many previously unknown fires. Such images will be used to prevent the scattering coal fires, and thus to treat them on time.

China is the world's largest coal producer and holds about 13 percent of global coal reserves. More then 100 burning areas have been indentified. Research at the International Institute for Geo-Information Science and Earth Observation, The Netherlands, suggests that between 100 and 200 Mt of high quality coal is consumed by spontaneous combustion every year. This amounts to approximately five to ten times of the Chinese annual export. The fires are so extensive that they produce about 2-3% of the total world carbon dioxide production associated with fossil fuels.

The Chinese fires also make a big, hidden contribution to global warming through the greenhouse effect, scientists said. Each year they release 360 million tons of carbon dioxide into the atmosphere, as much as all the cars and light trucks in the United States.

The Chinese mining industry is one of the few in the world
that actively tries to extinguish coal mine fires on a broad scale.

Worldwide Underground Coal Mine Fires

World Map of Coal Mine Fires Each red dot above indicates a nest or series of coalmine or coal deposit fires. These fires represent a significant portion of the overall greenhouse gas emissions which are suggested to be the cause of global warming. Either way, these fires are a significant contribution to air pollution around the world, formation of carbonic acid rain and cause significant destruction of nonrenewable energy resources

The following is an extract from TIME SCIENCE magazine (2010)

Internationally, thousands of underground coal fires are burning on every continent except Antarctica. Anupma Prakash, a University of Alaska at Fairbanks geologist who maps the fires, calls them "a worldwide catastrophe with no geographic territory, and if we don't take care of them they're going to take a toll on us." The problem is most acute in industrializing, coal-rich nations such as China, where underground fires are consuming at least 10 million tons of coal annually (other sources say multiply that amount twentyfold). In India, 68 fires are burning beneath a 58-square-mile region of the Jhairia coalfield near Dhanbad, showering residents in airborne toxins. "Go there and within 24 hours you're spitting out mucous with coal particles," Prakash says. "It's bad, worse than any city, anywhere."

Quantifying the amount of pollution that underground fires create is as difficult as spotting them. The smoke escaping through vents contains carbon dioxide, methane, mercury and at least 40 toxic compounds - "a whole soup of nasty stuff," according to Glenn Stracher, a geologist at East Georgia College in Swainsboro, Ga., who studies the emissions. But that soup's ingredients vary from hour to hour, even vent to vent, and some of the gases also escape through adjacent soil. "It's not like the oil well in the Gulf, where you measure how much is coming out per unit of time," Stracher says. "Making calculations is a tricky business." He and other researchers readily admit that global coal fire emission estimates - 40 tons of mercury spewing into the atmosphere annually, and 3% of the world's annual CO2 emissions - are imprecise. But the negative implications for human health and global warming, they say, are clear.

With that in mind, some countries are investigating whether snuffing the fires could help them earn carbon credits under the Kyoto Protocol, and are stepping up prevention awareness. Though geologic records show evidence of underground coal fires dating to the Pleistocene era, modern-day coal fires are often an unintended side effect of mining operations that open coal seams to oxygen. Once exposed, the coal undergoes a chemical reaction that releases heat. In some climate conditions the coal spontaneously combusts. Otherwise, lightning, wildfires or an ill-placed spark can trigger the blaze. The flames rip inside the buried coal seams at temperatures exceeding 1,000°F, sometimes fed by oxygen trapped in the microscopic spaces between dirt particles. They're also assisted by a process known as subsidence: as the burning coal turns to ash, it causes the overlying ground to crack and collapse, supplying the fire with fresh air.

Extinguishing a fire amounts to a frustrating, expensive version of whack-a-mole. "You put one down, then 300 feet later another one picks up," says Engle. Firefighters can dig up the burning coal or form a break around it, and they sometimes pump ignited seams with cryogenic liquids that absorb enough heat to prevent burning. But large coal deposits can span several miles at 90 feet deep and 100 feet thick, creating a honeycomb of pores that always leaves a few pockets of fire-fanning oxygen. That means the same fire can later reignite — and fighting underground fires doesn't come cheap. The U.S has already spent more than $1 billion battling underground coal fires, according to the Office of Surface Mining. Officials gave up hopes of dousing the extensive Centralia, Pa., fire because the job would have cost more than $600 million — and that was in 1983.

Less expensive alternatives are beginning to hit the market, from special heat-resistant grouts to a fire-smothering nitrogen foam, and other innovative solutions are on the way. "Look, tornadoes and earthquakes are here and gone," Stracher explains, "but these fires will burn for hundreds of years if we don't do something about them." It seems that where there's smoke there is indeed fire, whether we can see the hidden flames or not.

Can't beat them… yet! But we can harness its energy…

In the USA there are approximately 600 coal mine fires that are burning over a period of 80 years. Other underground coal mines fires are located in Russia and in several east European countries. These fires are located at shallow depth and the depth in many cased do not go beyond 400-500 m. The heat energy from these coal fires is not put to use. Yet the Heat Exchanger technology, commonly used in geothermal power generation, can easily be adopted in regions where underground coal mine fires is common. Continuous heat source from burning coal seams underground will provide continuous electric supply and, to some extent, can controls underground coal fires, limit CO2 emission and generate electricity to million rural homes. The technology exists (among others) and all that is required is the will-power to implement them!

1. Upper left image -The steaming hills near Hazard, Kentucky, USA - a coal seam fire that started in 2007.
2. Upper right image - Fire frequently breaks out from a coal mine seam in Browns Branch near Van in Boone County, West Virginia, USA

3. Residents of a Kuli Dhaori or miner's slum, in the Jharia coalfield of India. Children living here with their families play in air polluted by toxic fumes from coal-fire gas while their parents work in the surface-coal mines.

4. Self-ingnited coal seam fire in China

Global Warming
Internationally, thousands of underground coal fires are burning now. Scientists blame uncontrolled coal fires as a significant source of greenhouse gases such as methane and CO2, which lead to global warming. Global coal fire emissions are estimated to include 40 tons of mercury going into the atmosphere annually, and 3% of the world's annual carbon dioxide emissions. The contribution of coal fires to the global pool of atmospheric carbon dioxide is little known but potentially significant.

The impacts of coal seam fires on climate change, and their contributions to global warming, are increasingly receiving expert attention. Now experts are asking if extinguishing or at least controlling mine fires in Asia might be a key to reducing global warming.

Decades-burning coal fires are unfortunately rather commonplace. In fact, it's estimated that a stunning 2-3% of the entire world's industrial carbon emissions may come from uncontained coal fires in China alone--where such fires burn 20 million tons of coal a year.

One of the worst underground fires in the United States, the Centralia, Pennsylvania mine fire, has been burning since May 1962. The fire was started when the local city council set trash ablaze in an abandoned strip mine that had been used as an illegal dump.

Since then, around $4 million has been spent to put the Centralia fire out, to no avail. It continues to burn today, moving through a vast network of abandoned mines that are still littered and lined with coal. No one knows how extensive these empty spaces are, and the effort to quell the blaze has come to an end. “It’s too expensive to tackle, and we’re not sure we can do it anyway,” says Alfred Whitehouse, chief of the Reclamation Support Division of the federal Office of Surface Mining.

The fire burned along a coal seam into tunnels located beneath Centralia, sending smoke and toxic fumes in the air and driving out almost all the town's 1,100 residents. A similar fire is now causing problems in Youngstown, Pennsylvania, where the Percy mine fire has been burning for more than 30 years.

The task of extinguishing underground coal fires, sometimes exceeding tempera- tures of 540°C, is highly dangerous and very expensive.