Billings, MT - An exhaustive government analysis says that at current prices and mining rates the largest coal reserves in the U.S. will be tapped out in just a few decades.
The finding upends conventional wisdom on the lifespan for the nation's top coal-producing region.
It also reflects the harsh economic realities for companies seeking to profit off extracting the fuel: Mining costs are rising, coal prices are falling, and political pressure growing over coal's contribution to climate change.
U.S. Geological Survey coal geologist Jon Haacke says the Powder River Basin along the Montana-Wyoming border has about 40 years of coal at current prices.
He says past claims that the U.S. had 250 years of coal came from "greatly inflated" estimates of how much coal could be mined.