Geothermal energy production

[racolvin]

I've been doing some reading on geothermal energy production and I'm having trouble reconciling something, so maybe the geniuses here can help me

In thermically active areas (Iceland, near volcanoes, etc, etc) the idea of a geothermal plant is easy to see. Some articles say that you can only do geothermal in these areas but I don't understand that.

The idea is that you pump water down a hole, the water gets heated up and comes back up as either steam or superheated water that will produce steam, that will in turn move a turbine, generating electricity. But since what you're doing is using the heat from the earth's crust what difference does it make where you put it? I mean surely its possible from almost any location to drill down far enough to get to an area that's hot enough to do the job. Given how far we can drill for oil, why is it a big deal to create a hole deep enough to find heat?

 

[bobsmith1492]

Originally posted by: racolvin
I've been doing some reading on geothermal energy production and I'm having trouble reconciling something, so maybe the geniuses here can help me

In thermically active areas (Iceland, near volcanoes, etc, etc) the idea of a geothermal plant is easy to see. Some articles say that you can only do geothermal in these areas but I don't understand that.

The idea is that you pump water down a hole, the water gets heated up and comes back up as either steam or superheated water that will produce steam, that will in turn move a turbine, generating electricity. But since what you're doing is using the heat from the earth's crust what difference does it make where you put it? I mean surely its possible from almost any location to drill down far enough to get to an area that's hot enough to do the job. Given how far we can drill for oil, why is it a big deal to create a hole deep enough to find heat?

The question is how close to the surface is the heat source? As you say, we could drill way, way down and find heat but it wouldn't be economical. Oil is valuable enough that we can spend a lot drilling because the oil is worth a lot and only going up (generally speaking).

Electricity from nuclear and coal is much more feasible economically unless your heat source is right at the surface a lá Iceland.

 

[racolvin]

I guess there's something about that argument that I still don't get. I mean if you go to the trouble to set up the drilling rig, that's the major expense, right? No matter where you do it drilling down far enough is just a matter of adding some additional lengths of drill bit and *eventually* you hit an area hot enough to be useful don't you? Sure in certain instances it will be farther down than others, or the rock strata will be extra tough to get through (granite?), but its still do-able.

The whole point of geothermal is to get away from burning of fossil fuels, so the coal thing isn't really relevant. As for Nuclear power, I would think the additional costs of radioactive issues (waste management, security, safety precautions, etc, etc) would more than compensate for some additional drilling costs for geothermal.

 

[BrownTown]

Originally posted by: racolvin
I guess there's something about that argument that I still don't get. I mean if you go to the trouble to set up the drilling rig, that's the major expense, right? No matter where you do it drilling down far enough is just a matter of adding some additional lengths of drill bit and *eventually* you hit an area hot enough to be useful don't you? Sure in certain instances it will be farther down than others, or the rock strata will be extra tough to get through (granite?), but its still do-able.

The whole point of geothermal is to get away from burning of fossil fuels, so the coal thing isn't really relevant. As for Nuclear power, I would think the additional costs of radioactive issues (waste management, security, safety precautions, etc, etc) would more than compensate for some additional drilling costs for geothermal.

You will eventually get hot enough, but you won't be able to get that energy out. Remember that your pipe is going to be very LONG and very THIN, this makes it a perfect heat exchanger, so all your energy is lost on the way up. not to mention the fact that the pumps which are circulating the water have to work harder to push it threw a longer pipe. There is a technological limit as well as the economic limit to geothermal power that limits it to only a few places in the world.

 

[racolvin]

Ahh, so it's not that we can't drill that far down anywhere we like, its that the physics of it make it useless to do so?

 

[dkozloski]

This idea makes geothermal power more practical.

http://www.chenahotsprings.com/index.php?id=90

 

[BladeVenom]

Then there's politics, the environmentalist will always complain. We could turn Yellowstone National Park into a geothermal electric plant, but I doubt that would be politically feasible.