The town of Centralia is almost completely deserted today. After some residents passed out from carbon monoxide inhalation and another fell into the earth in 1981, when the ground suddenly collapsed—as the coal burns away, the ground above it often subsides into the resulting cavity —Pennsylvania received $42 million from Congress to relocate Centralia’s residents. Folks accepted the buyout one by one, and their homes were demolished to discourage squatters. (Nine holdouts are still fighting eviction today.) The town now looks like a giant vacant parking lot. A few intersections still sport stop signs, which spray painters have modified to read “Don’t STOP believing.” Aside from the eerie emptiness, signs of the fire below are subtle. On a day in January, dead grasses bristle with ice along the edges of long cracks in the earth, and wisps of gas drift here and there. An area the size of a small house recently sank about three feet, and a bright green band of vegetation flourishes in the steaming, broken earth around it.
When Stracher first visited Centralia in 1991, the town looked even more like a disaster zone. Stracher had just finished his postdoctoral training in metamorphic petrology; as a new professor at Bloomsburg University of Pennsylvania, he went to Centralia on a geology field trip. He was horrified by the sinkholes encased in sulfur and other precipitated minerals, the huge cracks in now-abandoned Highway 61 near town, the thick fumes rising from a ravine called Death Valley, and the sulfur-laden trees around the ravine. The town’s Catholic church was still standing then. Stracher posed for a photograph next to a mournful sign outside the church that read, “Centralia: Coal mine fire is our future.”
“The fire had been burning so long by then,” he recalls. “I wondered what long-term effect it was having on the atmosphere and groundwater, even on people who didn’t live there.”
At that point, Stracher did not know very much about coal, but he had a strong background in chemical thermodynamics. He decided to study the behavior of the sulfur coming out of Centralia’s burning coal. In 1995 he reported that some of the sulfur crystallized and stayed on the ground, potentially tainting the local water, and some of it floated away as a gas, polluting the air. Nine years later, he and a former student published an article in the International Journal of Coal Geology titled “Coal Fires Burning Out of Control Around the World: Thermodynamic Recipe for Environmental Catastrophe.” Over the next few years, Stracher was asked to put together symposia, one for the American Association for the Advancement of Science and another for the Geological Society of America. By that time, coal fires had become his life work.
After that first trip, Stracher quickly learned that Centralia was not America’s oldest or biggest coal fire. It was not even Pennsylvania’s oldest or biggest coal fire. At last count, the United States had 112 documented underground fires like Centralia and Ruth Mullins, along with many more yet to be counted. In addition to the underground fires, there are also 93 known surface coal fires, some of them in huge waste piles created during the process of coal mining. Stracher mentions a 100-foot-high burning “gob pile” (containing pieces of coal mixed with mudstone) near Birmingham, Alabama. The pile caught fire 20 years ago and was apparently extinguished at the time. But it reignited in 2006, emitting large amounts of smoke and toxic gases that caused respiratory complaints; the effort to extinguish it for good was just completed last March. Other surface fires occur where coal seams that sit close to the earth’s crust are ignited by lightning strikes, forest fires, or brushfires. The coal-rich American West has a long history of such fires—in fact, the Powder River, whose basin in northeast Wyoming and southeast Montana is the source of about 40 percent of America’s coal, was so named because the area smelled like burning gunpowder.
But America’s problem with coal fires is small compared with that of the rest of the world, where untold thousands of coal fires—no one can come up with a number judged to be even remotely accurate—burn unchecked. Eastern India has the densest concentration of coal fires in the world. Sixty-eight of them burn within a 174-square-mile region in the Jharia Coalfield in the state of Jharkand, some right next to areas where mining families live.
In China, estimates of the amount of coal consumed or made inaccessible by uncontrolled fires runs as high as 200 million metric tons per year, 10 percent of the country’s total coal production. Indonesia, a major exporter of coal to the Pacific Rim, has many thousands of coal fires. Whitehouse spent several years there fighting the burn. In a 2004 paper, he stated that the number of coal fires in eastern Borneo might be as high as 3,000. Today he thinks even that estimate was far too low. “The real number is so astronomical that no one would believe it,” he says. “The published numbers are about one percent of what could actually be there.”
Most of the coal fires in Borneo start when local farmers and plantation owners burn brush to clear land for planting, accidentally igniting a coal seam just under the surface. Fires in both abandoned mines and waste piles sometimes start because of a nearby blaze, but they can also ignite through spontaneous combustion: Certain minerals in the coal, such as sulfides and pyrites, can oxidize and in the process generate enough heat to cause a fire.
Given the implications for safety, health, and climate, the paltry attention paid to coal fires puzzles and angers many. “Most of our efforts are unfunded or funded with a shoestring budget,” says Anupma Prakash, a geologist at the University of Alaska with a career-long interest in coal fires. She, Stracher, and Ellina Sokol of the Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, are coeditors of Elsevier’s four-volume Coal and Peat Fires: A Global Perspective, the first volume of which will be published this year. Even other scientists can find the issue obscure. “People ask me why they should worry about coal fires and want me to give them some numbers and hard facts, but the reliable quantitative data are not there at the moment,” Prakash admits.
The USGS team wants to plug that gap, deploying ground sensors to tally the surface carbon dioxide emissions from a coal fire and then comparing the measurements with those from aerial surveys of the same fire using an infrared camera. By calculating the amount of burning coal needed to produce the hot spots picked up by the infrared, scientists can determine the amount of carbon dioxide such a fire should release. If both methods yield comparable measurements, the researchers will know they are closing in on solid data.
Last year the team spent three days clambering around the Powder River Basin, measuring gases from 29 vents at three fires. This alone would have given an incomplete assessment of emissions, because coal fires also release gases through the soil. So USGS geochemist Mark Engle built an “accumulation chamber” that measured gases coming out of the ground along a 119-point grid. He found that even in places where burning coal was so deep in the ground that there was no visual evidence on the surface, there were still significant amounts of carbon dioxide rising up. In fact, nearly as much CO2 entered the atmosphere through the soil as from the vents. “The gas diffused out of the soil is not real obvious,” Engle says. “The ground is not necessarily hot, and you can’t trust the vegetation to tell you what’s going on.”