Naked Science Forum
General Science => General Science => Topic started by: Eric A. Taylor on 29/09/2010 13:17:10
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I first heard of geo-thermal energy in the early 90's and got really excited that it might be a very good, clean energy source. I did some research on it and was very badly let down.
Geo-thermal is fairly straightforward. You drill a deep hole in the ground, deep enough so the heat from inside the earth will allow you to boil water pumped through the hole. This works best in places where magma is close to the surface. Seems like a great idea. Nearly unlimited power and no carbon footprint.
Well not quite. Trouble is there's lots of very toxic things down there. When you pump the water down there the hole toxic things are picked up by the water then carried to the surface, where when the water cools, they turn back to solids, mucking up your steam turbines. Not to mention, what are you going to do with all this toxic water?
If you don't believe me take a look at Yellowstone NP. Almost every hydro-thermal vent is surrounded by a soft brittle rock called gyserite. Where trees have been inundated the water is drawn into the tree killing it and preserving the wood. It's really quite dramatic. (I have pictures and will post some here if I can figure out how).
Given these problems, why is geo-thermal still being considered?
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I happen to know quite a bit about geezerite [:)]
Er, well, you don't have to put the mineral laden water into the turbines. You can run it through a heat exchanger to convert much purer water into steam to drive the turbines, but I suppose you still have to watch that the minerals don't clog up the heat exchangers. It's possible they also treat the water that goes through the ground, but I'm not sure about that.
They do seem to be able to make a go of geothermal energy in Iceland and New Zealand, and there are some spots in the US that do too. I seem to remember driving past one somewhere - I think it may have been in the top end of Nevada.
The main thing is the temperature of the geothermal reserve. If it's not hot enough, it does not produce much mechanical energy. There are a lot of places where it's not hot enough to be much good for power generation, but it can be used as a good source for heat pump heating systems.
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Putting a geothermal plant in the Newberry Crater has been talked about for many years. It's a shame that the wikipedia article about it is so out of date.
http://en.wikipedia.org/wiki/Newberry_Crater#Geothermal_Power (http://en.wikipedia.org/wiki/Newberry_Crater#Geothermal_Power)
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