Hidden Coal Fires Create Visible Problems
DENVER, Colorado, February 14, 2003 (ENS) - Fires are blazing in underground coal seams around the globe, sending tons of soot, toxic fumes and greenhouse gases into the atmosphere. These fires can burn unchecked for decades, but researchers speaking at a scientific meeting today say new techniques offer hope for extinguishing the blazes.
These fires threaten the environment and human health, scientists said today at the American Association for the Advancement of Science (AAAS) Annual Meeting in Denver. Although some coal fires can be impossible to extinguish, new technologies provide hope that experts may someday be able to control them, if not put them out altogether.
"Coal fires are a global catastrophe," said Glenn Stracher of East Georgia College. But surprisingly few people know it, he added.
"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."
"These ultra-hot fires can occur naturally, when oxidation reactions promote spontaneous combustion. However, they are frequently caused by humans. For example, during mining, coal seams can be ignited by sparks from cutting and welding, electrical work, explosives or even cigarette smoking."
In China, small illegal mines are ablaze across the northern region of Xinjiang. Local miners often use abandoned mines for shelter, and may burn coal within the shafts for warmth.
Besides fires in coal mines, burning coal may also be located in coal waste piles or natural coal seams, often ignited by heat from above ground fires set to clear the landscape for farming.
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.
Once underway, coal fires can burn for decades, even centuries. In the process, they release large volumes of greenhouse and noxious gases and soot particles into the atmosphere.
A team from the Netherlands studied the environmental effects of underground fires in China, concluding that the fires release up to 360 million metric tons of carbon dioxide each year, equal to two to three percent of global carbon dioxide releases.
While researchers have yet to measure emissions from all coal fires, the large scale burning in coal producing countries may be making a major contribution to global and regional climate change, as well as regional air pollution and human respiratory problems, according to the panelists who spoke today in Denver.
"One way to deal with greenhouse emissions limits may be to stop coal fires," said Paul van Dijk of the International Institute for Geo-Information Science and Earth Observation (ITC), in the Netherlands.
The environment impacts of coal fires do not stop with the atmosphere. The release of toxic elements like arsenic, mercury and selenium can also pollute local water sources and soils. As the coal is burned away, the land itself can subside, posing a risk to buildings and changing the routes of streams.
Heat from the fires can kill vegetation above, even igniting forest fires. Last summer, a fire in an underground coal seam in Colorado sparked a blaze that scorched more than 12,000 acres of forest, destroyed two dozen homes, and threatened the resort town of Glenwood Springs.
Disasters like these are fueling efforts to fight underground coal fires. One engineering firm, Goodson and Associates, Inc., has developed a heat resistant "grout": a mixture of sand, cement, fly ash, water and foam that can be pumped around burning material. The grout, called Thermocell, helps to cut off the fire's oxygen supply and allow the blaze to cool down.
While traditional coal fire fighting techniques require large equipment used close to the red hot fire, the readily flowing grout can be pumped from a distance away," said Goodson and Associates owner Gary Colaizzi. Experts could also inject the grout into cracks, vents or excavated trenches to seal off the fire and prevent its spread, Colaizzi added.
The grout could even be used to prevent fires, according to Colaizzi, if it were sprayed onto exposed surfaces of coal seams just after strip mining, to seal them from oxygen.
Because coal fires are dangerous to approach, and typically burn underground, predicting where they will spread has been a major challenge, especially in remote areas like northern China.
In collaboration with the Chinese government, van Dijk and his colleagues have used a combination of remote sensing data and GIS technology to detect and monitor coal fires in the northern regions of the country. Their results are helping researchers explore how these fires evolve and what the best approaches might be for extinguishing them.
Ultimately, these techniques should allow scientists to estimate how much carbon dioxide these fires are emitting, van Dijk said.
Another collaboration, involving the United States and Indonesian governments, developed out of concern over the smoke and haze from forest fires that has affected human health in countries such as Indonesia, Singapore and Malaysia in recent decades.
"What went up in smoke in Indonesia makes it one of the worst polluters in the world," said Whitehouse.
Coal fires now threaten some of Indonesia's national parks and a nature preserve that is being used as a reintroduction site for the endangered orangutan, Whitehouse added.