GeologyRocksusing earth's heat?
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using earth's heat?
Fri, 12/01/2006 - 08:54I'm not from CSM, but seeing as he seems to be asleep (or drunk knowing him), i'll have a go at answering!
It is possible, and it is done. But it has to be done in the right area. In cornwall (The Rosemanowes 'Hot-Dry Rock' project i think!) They are tring what you were thinking about. Drilling down about 2K into the granite, and then pumping watere down, getting steam back up. Easy(ish).
But this won't happen all over the world. There has to be a nice convienient batholith that is still warm, (at least 100 C i think was needed) or a volcanic area. Look up icelandic geothermal energy projects. or just go onto google and type 'geothermal powerstations'. should be tonnes of places.
Dont know of any other ways to get the energy out of the ground yet. although i was reading somewhere about a direct heat to electricity transformer. That might work. but i think it was about 20% efficient on a good day!
We will probably hear form james or my lecturer if i have miss-quoted anything or said something stupid.
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using earth's heat?
Fri, 12/01/2006 - 11:03It's been used for some time now.
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Mon, 12/04/2006 - 10:46Not too sure if I am the CSM contingent (or ex-CSM contingent as it is in my case) you are referring to - however, the Hot Dry Rock project finished (as far as I'm aware) a number of years ago (before I was at CSM!), and was fairly unsuccessful. However, as Matt says above, this sort of energy has been around a fairly long time, and is used extensively in New Zealand and Iceland. Recent trials in the Aegean were moderately successful on Milos Island, however scaling in the pipes presented a major problem - much like limescale in house pipes, however, the scale material being generated at depth on Milos was galena!
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Mon, 12/04/2006 - 20:33icelandic geothermal energy projects
Theres the great museum in Thingvallavatn that I visited all about the geothermal heating system it was great. You can litterally see these huge pipes going into the ground and coming up on the other side of the plant with clouds of steam surrounding them.
heres an awesome website all about it! http://www.energy.rochester.edu/is/reyk/
On the CSM front "Hot Rock Project" Arn't they still doing somthing with that. On my wander around there this reneable energy chap was telling this girl how all the halls are run off it?
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Sat, 12/09/2006 - 15:09The CSM guy returns! too many essays to write recently.
The power from radioactive elements within the earths interior is 31,688GW. That is about 31thousand Hinkley point nuclear power stations but whent he power is dispersed over the earths surface it becomes 62mW/m^2 which is to low to be practically used. But this energy has been concentrated in areas such as plate boundaries (Iceland) or rocks containing radioactive isotapes such as crystalline granite (Cornwall). There are two main ways of extracting this energy
1) Aquifer
This is where an aquifer lies horizontally above a heat producing rock e.g. crystalline granite and as water passes through the aquifer it is warmed to above 100oC. But because the pressure is much higher here the water does not boil, this water is bought to the surface at the sam pressure so it reamins a liquid but once it reaches a turbine the pressure is dropped and the water flashes to steam and passes through the turbine.
Sustainable?
An example is in Tuscanny where there is 500MW sustainable thermal power output but the current usage is over 3000MW meaning the energy will become exhaused soon and will need time to recover. This is called heat mining for this reason.
2) Rosemanowes
Two holes are drilled into the granite and water pumped down one heated by the 230oC granite. It is then brought to the surface at pressure and flashed to steam and put through a turbine. However this was found to not quite heat the water enogh to make it viable at the time.
If we went deeper or electricity prices go sky high, things might be different.
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Sat, 12/09/2006 - 15:16Just remembered ground source heat pumps. These are influenced more by the atmosphere but they go in the ground.
It works by laying a pipe in 1.8metre deep trenches or in deep boreholes, water is pumped through the pipes and in a heat pump some energy taken from it and amplified by 4 to 6 times. Providing a max temp of 55oC from average ground temperature of c.10oC. Effectively it is a fridge in reverse and the pipes in the groud are like the black pipes on the back of your fridge. These are good because they can provide all your heating and hot waterdemands with a 60% CO2 reduction and a small fuel bill reduction.
Want to know any more just let me know
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Submitted by KU40 on Thu, 11/30/2006 - 22:46.so i was sitting in class today, sorta not paying attention but thinking instead about other ways to create the steam that turns the turbines in power generation. and I thought about the earth's internal heat and if we could somehow use it to vaporize the water. would it be possible/feasable?
maybe drill a hole down a couple kilometers and pump water into it with another pipe for bringing the steam back up. though I suppose the water vapor would probably condense by the time it got back up to the surface. but what do you think, are there any other ways to utilize this vast resource under our feet?