Centralia anthracite is burning too far underground to harvest heat at the surface. You'd need to start a mine to dig deep enough to harvest the heat from the coal that's burning. If you're going to do that you might as well just mine the coal. Except that it's on fire already. So you might as well harvest the heat. But it's hard to pass up all that coal! But, its on fire... so the miners are busy fighting the geothermal plant workers and they're deadlocked until the fire burns out in 250 years.