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Geothermal Power, Perpetual?  
User currently offlineLehpron From United States of America, joined Jul 2001, 7028 posts, RR: 21
Posted (8 years 9 months 3 weeks 3 days 12 hours ago) and read 1263 times:

My thermodynamics professor refered to the atmosphere for all practical purposes as a TER, a thermal energy resevoir, such that any energy dumped into it would not vary the total much. I.e. the hot exhausts from a jet engine to the air isn't going to render the weather warmer tomorrow.

Even if the entire planet harnessed the heat from the Earth to generate electricity (closed cycle, heated underground), it could take maybe millions of years to cause any change in then temperature down there.

Could it be technically perpetual considering it within human memory, unlike fossil or biofuels, or solar or nuclear? I do not think there would be any shortages or short-term environmental side effects. But then this question did pop in my mind like an hour ago.  Smile

What could we do to make this happen?


The meaning of life is curiosity; we were put on this planet to explore opportunities.
22 replies: All unread, jump to last
 
User currently offlineOly720man From United Kingdom, joined May 2004, 6820 posts, RR: 11
Reply 1, posted (8 years 9 months 3 weeks 3 days 11 hours ago) and read 1253 times:

If geothermal power is used then eventually all the power that was converted below ground will appear as energy above ground.

Would this heat up the world? Possibly. In comparison with the amount of incoming solar irradiation (about 2 kw/m sq) geothermal will probably be minor. Also, energy does radiate from the earth.

The environmental impact would probably be the construction of all the power lines to get the power from the geothermal plants to where the energy is needed.



wheat and dairy can screw up your brain
User currently offlineEilennaei From , joined Dec 1969, posts, RR:
Reply 2, posted (8 years 9 months 3 weeks 3 days 9 hours ago) and read 1245 times:

Quoting Oly720man (Reply 1):
the geothermal plants

What geothermal plants? Here you just drill a 100 meters deep hole in the granite and you have the heating/cooling for your house or two.


User currently offlinePyrex From Portugal, joined Aug 2005, 4026 posts, RR: 28
Reply 3, posted (8 years 9 months 3 weeks 3 days 8 hours ago) and read 1240 times:

Quoting Oly720man (Reply 1):
The environmental impact would probably be the construction of all the power lines to get the power from the geothermal plants to where the energy is needed.

Actually that is a myth about geothermal energy, that it has no environmental impact. When you harness the heat of the earth for your own needs you basically have to release a lot of gases that should not be released (some of those can be nasty stuff, lots of sulphur). Geothermal power may be renewable, as it is not foreseeable that we could exhaust it in the medium term, but it certainly isn't "free energy", environmentaly speaking.



Read this very carefully, I shall write this only once!
User currently offlineKlaus From Germany, joined Jul 2001, 21495 posts, RR: 53
Reply 4, posted (8 years 9 months 3 weeks 3 days 8 hours ago) and read 1239 times:

Quoting Pyrex (Reply 3):
When you harness the heat of the earth for your own needs you basically have to release a lot of gases that should not be released

Not necessarily. When you're using heat exchangers no gases will be released to the surface. This will be a factor only in regions with high volcanic activity with large amounts of heated gases close to the surface.


User currently offlineMt99 From United States of America, joined May 1999, 6626 posts, RR: 6
Reply 5, posted (8 years 9 months 3 weeks 3 days 6 hours ago) and read 1234 times:
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Quoting Klaus (Reply 4):
Not necessarily. When you're using heat exchangers no gases will be released to the surface. This will be a factor only in regions with high volcanic activity with large amounts of heated gases close to the surface.

You are talking about 2 different things. Geothermal Heating - which, is just like you say a heat exchanger (same as heating water using the sun), and Geothermal Electricity.

Geothermal Electricity is nothing but a steam plant. The Steam is produced by underground water heated by the earth which moves a turbine. When this steam cools it becomes water which contains sulphur and other kinds of not so great stuff. Some plants re-inyect this water back into the ground so it can be resused - at least some of it.

I still think that pumped storgage hydro-electric plants are the way to go.



Step into my office, baby
User currently offlineJwenting From Netherlands, joined Apr 2001, 10213 posts, RR: 19
Reply 6, posted (8 years 9 months 3 weeks 3 days 6 hours ago) and read 1226 times:

I wonder what the longterm consequences on the planet itself (not the atmosphere) would be from really large scale use.
You're extracting energy from the planet after all, that can only mean that either the planet (probably starting with the mantle) cools down or that energy is reabsorbed from somewhere else (which can only be the atmosphere).

Yes, on the current scale the impact is likely so minimal that it can't be detected.
But the current scale is similar to what wind power was 20 years ago when the climate changes (change in wind and rain patterns and temperature gradients in their vicinity as well as noise and dead birds) produced by large arrays of wind generators had not been observed.



I wish I were flying
User currently offlineKlaus From Germany, joined Jul 2001, 21495 posts, RR: 53
Reply 7, posted (8 years 9 months 3 weeks 3 days ago) and read 1213 times:

Quoting Mt99 (Reply 5):
You are talking about 2 different things. Geothermal Heating - which, is just like you say a heat exchanger (same as heating water using the sun), and Geothermal Electricity.

No, I don't. I'm just talking about two separate ways of extracting energy, not about the target energy form. You can use the heat exchanger method for generation of electricity as well.

Quoting Jwenting (Reply 6):
I wonder what the longterm consequences on the planet itself (not the atmosphere) would be from really large scale use.
You're extracting energy from the planet after all, that can only mean that either the planet (probably starting with the mantle) cools down or that energy is reabsorbed from somewhere else (which can only be the atmosphere).

Quite right. It is not entirely inconceivable, for instance, that large-scale localized heat extraction could lead to a local cooldown which might change magma flow patterns below and possibly have an impact on eruptions or earthquakes.

Plus it is not a renewable energy source, it is simply a very large one.


User currently offline777236ER From , joined Dec 1969, posts, RR:
Reply 8, posted (8 years 9 months 3 weeks 3 days ago) and read 1201 times:

Quoting Klaus (Reply 7):

Plus it is not a renewable energy source, it is simply a very large one.

Nothing is a renewable energy source. There's finite energy in the universe.


User currently offlineNewark777 From United States of America, joined Dec 2004, 9348 posts, RR: 29
Reply 9, posted (8 years 9 months 3 weeks 3 days ago) and read 1200 times:

Quoting Mt99 (Reply 5):

Geothermal Electricity is nothing but a steam plant. The Steam is produced by underground water heated by the earth which moves a turbine. When this steam cools it becomes water which contains sulphur and other kinds of not so great stuff. Some plants re-inyect this water back into the ground so it can be resused - at least some of it.

Who says you must use the water from below ground? You would simply use the heat exchangers to heat the clean water on the surface, which would turn the turbines.

Same with a nuclear power plant, the water and steam that spins the turbines never comes in contact with nuclear material.

Harry



Why grab a Heine when you can grab a Busch?
User currently offlineMt99 From United States of America, joined May 1999, 6626 posts, RR: 6
Reply 10, posted (8 years 9 months 3 weeks 3 days ago) and read 1200 times:
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Quoting Klaus (Reply 7):
heat exchanger method for generation of electricity as well

How?



Step into my office, baby
User currently offlineJafa39 From , joined Dec 1969, posts, RR:
Reply 11, posted (8 years 9 months 3 weeks 3 days ago) and read 1198 times:

The geothermal plants in Rotorua have to be very carefully managed as the hot water used in the process has to be put back in the ground to heat up again, this causes a gradual reduction in the size and temp of the geothermal field and also problems with subsidence.

There are many lgoistical and physical problems associated with it, also the enviromental impact on the energy source itself.

Far better that all men have dynamos attached to their arses so that having sex produces energy which keeps the house powered....could change our lives forever  Smile so if the missus wanted to watch Shortland Street, she'd have to put out first!!


User currently offlineKlaus From Germany, joined Jul 2001, 21495 posts, RR: 53
Reply 12, posted (8 years 9 months 3 weeks 3 days ago) and read 1194 times:

Quoting Mt99 (Reply 10):
How?

The same way it's done in any nuclear power plant: By generating steam in the heat exchanger which drives a turbine, is re-condensed and then re-used in a closed system.

For lower temperature differentials a Stirling engine can be more efficient than a turbine.

Peltier elements can achieve a direct conversion to electricity, but they are relatively inefficient.

[Edited 2006-01-11 22:19:08]

User currently offlineMt99 From United States of America, joined May 1999, 6626 posts, RR: 6
Reply 13, posted (8 years 9 months 3 weeks 3 days ago) and read 1192 times:
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Quoting Newark777 (Reply 9):
You would simply use the heat exchangers to heat the clean water on the surface, which would turn the turbines.

How would you build it? to have clean water out, it would not have to touch the ground. Meaning you would have to run the water through a pipe or something. How do you build a pipe at very very temperatures thousands of feet under ground?



Step into my office, baby
User currently offlineMt99 From United States of America, joined May 1999, 6626 posts, RR: 6
Reply 14, posted (8 years 9 months 3 weeks 3 days ago) and read 1178 times:
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Quoting Klaus (Reply 12):
The same way it's done in any nuclear power plant: By generating steam in the heat exchanger which drives a turbine, is re-condensed and then re-used in a closed system.

Sure, but can it be built?

Nuclear power plants arent "fired up" until everything is built. The earth is hot already.

[Edited 2006-01-11 22:25:16]


Step into my office, baby
User currently offlineNewark777 From United States of America, joined Dec 2004, 9348 posts, RR: 29
Reply 15, posted (8 years 9 months 3 weeks 3 days ago) and read 1177 times:

Quoting Mt99 (Reply 13):
How would you build it? to have clean water out, it would not have to touch the ground. Meaning you would have to run the water through a pipe or something. How do you build a pipe at very very temperatures thousands of feet under ground?

Not sure about the execution, I'm just speaking in theoreticals.

Harry



Why grab a Heine when you can grab a Busch?
User currently offlineBirdwatching From Germany, joined Sep 2003, 3823 posts, RR: 51
Reply 16, posted (8 years 9 months 3 weeks 3 days ago) and read 1176 times:

Quoting Jafa39 (Reply 11):
Far better that all men have dynamos attached to their arses so that having sex produces energy which keeps the house powered....could change our lives forever Smile

That is the single most funny thing I've ever read in this forum! RR +1
 laughing   laughing   laughing   laughing   laughing   laughing   laughing   laughing   laughing   laughing   laughing   laughing 



All the things you probably hate about travelling are warm reminders that I'm home
User currently offlineMt99 From United States of America, joined May 1999, 6626 posts, RR: 6
Reply 17, posted (8 years 9 months 3 weeks 3 days ago) and read 1172 times:
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Quoting Newark777 (Reply 15):
Not sure about the execution, I'm just speaking in theoreticals.

Its ok. Being in the Consulting business i am used to thinking about all aspects of a project feasibility.

Some great ideas only work in the Lab



Step into my office, baby
User currently offlineKlaus From Germany, joined Jul 2001, 21495 posts, RR: 53
Reply 18, posted (8 years 9 months 3 weeks 2 days 23 hours ago) and read 1167 times:

Quoting Mt99 (Reply 14):
Sure, but can it be built?

Probably - but whether it would be cost-effective is another point entirely...


User currently offlineMt99 From United States of America, joined May 1999, 6626 posts, RR: 6
Reply 19, posted (8 years 9 months 3 weeks 2 days 23 hours ago) and read 1159 times:
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Quoting Klaus (Reply 18):
Probably - but whether it would be cost-effective is another point entirely...

It only takes time and money.. right?  Smile



Step into my office, baby
User currently offlineKlaus From Germany, joined Jul 2001, 21495 posts, RR: 53
Reply 20, posted (8 years 9 months 3 weeks 2 days 23 hours ago) and read 1154 times:

Quoting Mt99 (Reply 19):
It only takes time and money.. right?

Pretty much (ahem)! Big grin


User currently offlineEilennaei From , joined Dec 1969, posts, RR:
Reply 21, posted (8 years 9 months 3 weeks 2 days 22 hours ago) and read 1142 times:

Quoting 777236ER (Reply 8):
There's finite energy in the universe.

That's right, since there's been observed a leak into another universe. What we typically call energy is just a side effect of the universe's mass being converted into radiation. The radiation has no capability to recreate the missing mass, so we're lost.


User currently offlineEilennaei From , joined Dec 1969, posts, RR:
Reply 22, posted (8 years 9 months 3 weeks 2 days 21 hours ago) and read 1132 times:

Quoting Eilennaei (Reply 21):
That's right, since there's been observed a leak into another universe

Oops you'll be advised to read that as ".. there's _never_ been..."


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