So... there are coal fires in various places around the world they can't seem to put out. Like in Centralia, PA. There's also a natural gas fire somewhere in Siberia, which looks really cool.

They can't put these fires out. They just keep burning underground.

So they might as well use them for geothermal power. Surely, since they already have goethermal power in various parts of the world, they have earth-drills that can handle the heat.

The only real issue that doesn't come up with normal geothermal is gaseous effluents from the coal escaping through cracks in the ground where you drill. Though normal geothermal I think has that problem sometimes too, just not with coal-produced gases.
-- EdwinBakery, Aug 02 2010

Centralia Steam Power Centralia_20Steam_20Power_3f
Previously Halfbaked [goldbb, Aug 03 2010]

Can I get about half of how to make this idea work? Something like shoot water in during the winter and look for steam coming out. Otherwise this is just saying two hot things are alike, and ignoring the pipes melting.
-- baconbrain, Aug 02 2010


As long as you've got a supply of water coming in and only slightly super-critical steam coming out, you wouldn't have any issue with pipes melting.

Or make the pipes out of refractory materials and it's not an issue.

Or simply your geothermal lines close to, but not into the burning areas, taking advantage of the heated rock.

This idea is definitely possible, and a creative use of an ongoing problem.
-- MechE, Aug 02 2010


Seems reasonable to me. One question: how much energy do these fires produce? I got the impression that the coal fires at least were sort of slow-burning.

Anyway, a [+] from me.
-- MaxwellBuchanan, Aug 02 2010


I like this idea. A lot. Why not make use of the underground coal fires, including the gaseous effluent as well? This turns a natural resource (coal) that had been turned into a blunder by whatever means (the fire) back into a natural resource. Bun. [+]
-- Grogster, Aug 03 2010


I like it too ([+]), although it might create an economic incentive to perpetuate or even start underground coal fires.
-- mouseposture, Aug 03 2010


HA!! Good Point, [mouse]! On the other hand, maybe they'd quit hollering about strip mining...
-- Grogster, Aug 03 2010


I guess you alluded to it in the idea description, but I it might be unreasonably risky with respect to human safety to try and construct a power plant atop a coal fire or a natural gas fire.
-- Cuit_au_Four, Aug 03 2010


If the plant was equipped with a suitable number of carbon monoxide detectors, it shouldn't be too dangerous.
-- goldbb, Aug 04 2010


I'm not sure you could make this work. Traditional generators are static affairs with a combustion chamber and having the necessary fuel brought in.

Trying to take advantage of these underground unstoppable fires would need a mobile generator constantly moving to where the fuel is burning. Underground that's going to be hard, surely?
-- Tulaine, Aug 05 2010


Underground coal fires burn fairly slowly. Keep the power plant in place, and extend yout pipes as needed. Keeping up with the heat shouldn't be to difficult.
-- MechE, Aug 05 2010


It seems to me that many of these coal fires are burning in coal beds that aren't large enough to be worth mining--not just to start mining, but to continue mining any more, even with equipment in place. So there isn't much coal in there.

There isn't much air in there either, as the coal is underground. So what coal there is down there is burning slow.

And the coal is scattered out. And surrounded by rock.

So there's a little coal, burning slow, spread out, surrounded by cold rock.

Yeah, let's tap that.

I'd like to see a system devised to burn large coal beds without mining, by injecting air and extracting energy, but I cannot bun this. [ ]
-- baconbrain, Aug 06 2010


Actually, most (not all) of these coal fires started in seams being worked.

Additionally, coal forms in layers that usually extend quite a ways, so it's not scattered.

It is burning slowly, but the volume of coal that is smoldering is usually fairly high (otherwise it would be simple to extinguish).

And if you were able to draw more energy out than the fire generates, well, you've suceeded in extinguising it, which is also a good thing.
-- MechE, Aug 06 2010



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