This is the most publicised aspect of coal pollution, but there's an underground secret...

Most of us recognise the struggle we're facing with our growing energy demand - and the pressure, indeed, the incentive, this places on industry to keep shoveling coal into the boiler room of our economies. What you may not be aware of, however, is that there is a fire burning below that is not intentionally fueled, but it burns nonetheless, and it's yet another dark side to coal - and a significant contributor to global warming.

In dozens of locations around the world, there are vast underground coal fires consuming millions of tons of coal - creating enormous environmental and human health problems and adding greatly to our climate change burden. Some of these fires have burned for decades - some for centuries.

Fires are burning in thousands of underground coal seams from Pennsylvania to Mongolia, releasing toxic gases, adding millions of tons of heat-trapping carbon dioxide to the atmosphere and baking the earth until vegetation shrivels and the land sinks.

Scientists and government agencies are starting to use heat-sensing satellites to map the fires and try new ways to extinguish them. But in many instances -- particularly in Asia -- they are so widespread and stubborn that miners simply work around the flames. - NY Times

It is said that the coal fires burning in China alone emit more CO2 into the atmosphere than all the cars and light trucks in the U.S. of A.

Photo credit: Anupma Prakash

One of the most troubling results of these fires, he says, is the carbon dioxide (CO2) they generate, including about 360 million metric tons of CO2 from coal fires in China alone. "The CO2 production of all of these fires in China is more than the total CO2 production in The Netherlands," Rosema says. This amounts to 2-3% of the annual worldwide production of CO2 from fossil fuels, or as much as emitted from all of the cars and light trucks in the United States. "Coal fires release a variety of potentially harmful gases [and] combustion by-products, including sulfur and particulates," says Glenn Stracher, associate professor of geology at East Georgia College in Swainsboro, Georgia. "The catastrophe that we're faced with is the fact that these fires are emitting noxious gases." In fire-plagued regions such as in Centralia, Pennsylvania, he says, the ground is littered with sulfur and other pollutants that have killed off virtually all visible plant and animal life. - Environmental Health Perspectives

This is not just a modern day occurrence. Underground coal fires have been reported from the earliest times.

The oldest documented coal fire on a global scale, which has been burning for over 2,000 years, is located in New South Wales, Australia.... In China, coal fires are mentioned in historic documents as early as 1000 AC in the travel report of Li Dao Yuan, who explored Northwest China during the “Northern Song Dynasty” (960-1280 AC). Also the travel documents of Marco Polo (1254-1324 BC) mention the “burning mountains along the silk road” as well as paleo coal fires in Xinjiang, which are dated back to be of Pleistocene age. - Encyclopedia of Earth

As you can tell from the dates mentioned above, coal fires can be caused naturally, without human intervention. Coal seams often run up to ground level, where they can be exposed to oxygen, lightning strikes, forest fires - or merely sufficient sunshine and heat - any of which can cause the fossil fuel to combust.

But, adding the human element magnifies the risk greatly. In coal mining, oxygen gains greater access to the coal seam, and the fine coal dust that is the inevitable result of mining makes combustion far more likely - as are risks of human-caused accidents.

These ultra-hot fires can occur naturally, when the right combination of sunlight and oxygen causes spontaneous combustion, but more often they are caused by humans. During mining, coal seams can be ignited by sparks from cutting and welding, electrical work, explosives or even cigarette smoking. - Mines & Communities

When the coal burns, the earth above can effectively 'cook', destroying CO2 mitigating plants and biodiversity. Additionally, the great caverns created when coal seams smolder themselves out of existence underground can cause dangerous land subsidence. In fact, the U.S. town of Centralia, Pennsylvania, mentioned in a quote above, had to be relocated for this reason. With global warming on the top of international agendas, I often wonder about house values of properties in coastal regions - but who ever thinks about experiencing a furnace below your home? The people of Centralia, Pennsylvania probably didn't either....

In 1979, locals became aware of the scale of the problem when a gas-station owner inserted a stick into one of his underground tanks to check the fuel level. When he withdrew it, it seemed hot, so he lowered a thermometer down on a string and was shocked to discover that the temperature of the gasoline in the tank was 172 degrees Fahrenheit (77.8°C). - Wikipedia

The Centralia fire, although dramatic for the residents involved, is very small compared to other coal fires around the world.

One coal fire in northern China, for instance, is burning over an area more than 3,000 miles wide and almost 450 miles long.

... He estimated that the Chinese fires alone consume 120 million tons of coal annually. That's almost as much as the annual coal production in Pennsylvania, Ohio, and Illinois combined. - Post Gazette

"For most people who don't live near one of these fires, it never reaches them," Stracher said. "There may be a little clip in the newspaper, but most people aren't aware of the extent of the problems involved in these fires."

According to Stracher's forthcoming article in the "International Journal of Coal Geology," scientists have determined that coal fires in China consume up to 200 million tons of coal per year. For comparison, coal consumption in the United States during 2000 was just over one billion tons, according to the U.S. Department of Energy. - Mines & Communities

While industry leaders are keen to exploit the potential of carbon sequestration in coal mining (well, they're not so much keen as they are simply being pressured to find a way to clean up their act) - should not putting out existing coal fires be regarded as excellent 'low hanging fruit' in reducing greenhouse gas emissions? In addition, the preventative measure of just leaving coal in the ground is not a bad tactic either!

At the UN Climate Change Conference in Bali, starting on 3 December, China's reliance on coal will come under closer examination than ever before. Yet few other than specialists realise that (according to the Netherlands Earth Observation Network), China's coal fires produce between 1 and 3 per cent of global carbon emissions. - New Statesman

Underground coal fires are, admittedly, notoriously difficult to put out. But I wonder if the absence of a market incentive has contributed to apathy on this front? If China's underground fires alone are the source of between 1-3% of global CO2 emissions, I think this is an area worth looking at. Don't you?

On a side note, some are looking at intentionally lighting underground coal fires, with the purpose of harvesting gas from underground. But that's a post for another day....

 

Further Reading:

• No More Coal
• Coal Fires - Encyclopedia of Earth
• Coal Fires- from Anupma Prakash, of the Univ. of Alaska-Fairbanks
• Fire Fighting and Prevention Downloadable Mining Publications
• Underground coal seam fire put out after 50 years in NW China
• Extinguishing the 1998 forest fires and subsequent coal fires in the Sungai Wain Protection Forest, East Kalimantan, Indonesia