Squeezing Cleaner Energy from Coal’s Waste

Coal mine methane could soon transform from problematic waste to valuable fuel

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In a Colorado valley where miners have harvested coal for more than a century, a second fuel—methane—escapes from the thick black seams of the Elk Creek mine. A system of boreholes and pipes around the mine funnels methane-rich gas to a modified truck engine. Using a trio of one-megawatt generators, the engine converts this methane to electricity for the local power grid.
Elk Creek is the first methane-to-energy project at a coal mine west of the Mississippi and the largest of its kind nationwide. But coal mines like Elk Creek contribute about 10 percent of methane emissions nationally and 6 percent of methane emissions worldwide, and they continue to release methane long after mining operations have ended. The gas also seeps from swamps, industrial flues, landfills, cattle farms and natural gas operations.

In fact, so much methane enters Earth’s atmosphere each year that globally it is the second largest contributor to climate change after carbon dioxide. Methane dissipates more quickly than carbon, but its strength as a greenhouse gas over a 100-year period is more than 20 times that of CO2.

Burning methane can generate energy or useful heat while lessening its climate impact—essentially reducing the gas to a weaker brew of water and carbon dioxide. At Elk Creek, burning just over 670,ooo cubic feet of methane per day—roughly 16 percent of the mine’s total methane emissions—in an internal combustion engine is expected to generate 24 gigawatt hours annually. That’s enough electricity to power roughly 2,000 homes.

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