4 ms·

Has anyone calculated how much energy could be extracted before the cooling of the earth's crust, due such geothermal extraction, would turn irreversible the re

by drtgh 2y ago

Has anyone calculated how much energy could be extracted before the cooling of the earth's crust, due such geothermal extraction, would turn irreversible the reservoir and unleash worse consequences than those "greenhouse gasses" mentioned? From how such progressive temperature change (extraction) would affect the dynamics of the Earth's core, among other things, to how it would affect such temperature to the nature chemical processes on the surface, how it would affect vegetal life (cultives), and so on. The planet is big, but we are talking about, lets say, a century of use or more. Has anyone calculated were would be the limit of holes (on geothermal a new hole each XX years due area cold down) before the "we never guessed that X could happen"?

JoeAltmaier 2y ago
Pretty sure the numbers are not comparable, not by many zeroes. Like, trillions of times more energy in the Earth's heat than humans could extract in a billion years. Add to that, Earth is heated by deep radioactive elements. A fission furnace. Not gonna burn out for a billion years, maybe not ever.
lukan 2y ago
- new heat is generated constantly in the earth by radioactive decay - how much is debated, but this alone probably dwarfs humans energy needs (the core of the earth is really, really BIG) The real danger is in creating local earth quakes, because that already happened.
- pfdietz 2y ago
  Actually, it's estimated radioactive decay in the Earth is about 20 TW, which is also about equal to the current global rate of primary energy consumption. Geothermal can be better described as heat mining than it would be exploiting a steady state heat flow.
- xeonmc 2y ago
  So essentially : - fusion - power of the Sun - fission - power of the Earth
  - antisthenes 2y ago
    No, it's all power of the Sun*. Fissile elements were created by massive star Supernovae elsewhere. Fusion is still the precursor. Except it's very quick catastrophic fusion :)
    - xeonmc 2y ago
      Then: - Fusion - powers the Sun - Fission - powers the Earth
      - rbanffy 2y ago
        Even solar is only indirect fusion. As is wind. Geothermal is... ancient friction combined to fission?
theideaofcoffee 2y ago
More than we could ever hope to extract at even heightened future consumption levels, which you could take to mean pretty much impossible, see a past comment of mine along these lines: [0] [0] https://news.ycombinator.com/item?id=38850786 https://news.ycombinator.com/item?id=38850786
- drtgh 2y ago
  Thanks. By your link we have a 47TW of annual heat loss from the Earth due to the surface heat flux, that makes 92 KW/Km² annual (Earth is 510M km² [148.9M km² of land]). If the thermal diffusivity can not feed a tinny surface hole more than 20-30 years after extracting just around 3-10 MW, where the sun is supposed to replenish the heat on summer also, what makes the scientific community to have faith the slowness in such thermal diffusivity will not bring consequences? Did anyone study it? ( EDIT: we are talking about more than several centuries, I guess, so my interest decreased proportionally. )
justinpombrio 2y ago
https://en.wikipedia.org/wiki/Geothermal_energy#Resources https://en.wikipedia.org/wiki/Geothermal_energy#Resources
piva00 2y ago
On the phone so won't try to even get to a ballpark but just thinking on the scale we are talking: a massive volume of a molten ball of rock with a thin crust I believe it'd take a fucking lot of energy to have any cooling. Even more where it'd be radiating out to space and "lost".
sfink 2y ago
First, if your extraction method is at all efficient, then much of the energy you extract is going to end up as heat again. Sure, it'll be somewhere it can more easily radiate to space, but rock is a pretty good thermal conductor too. Second, Earth is big. Like, really big. I once did a napkin calculation of the proportional depth of the ocean. How much of a "water world" are we, really? What would it be like for some cosmic being to grab onto the Earth and throw it? Assuming I did it right, the Earth is basically a bowling ball that someone heavily misted with a spray bottle, resulting in an average of 0.4mm of water resting on the ball's surface. (Marianas trench is 6.8 miles deep, diameter of Earth is about 8000 miles, bowling ball is 8.6 inches in diameter. To be fair, that's like 10 squirts of spray.) Said cosmic being would just have to wipe it off with a rag to avoid it slipping out of its hands and accidentally clobbering Alpha Centauri in several years.

by drtgh 2y ago

JoeAltmaier 2y ago

Pretty sure the numbers are not comparable, not by many zeroes. Like, trillions of times more energy in the Earth's heat than humans could extract in a billion years. Add to that, Earth is heated by deep radioactive elements. A fission furnace. Not gonna burn out for a billion years, maybe not ever.

lukan 2y ago

- new heat is generated constantly in the earth by radioactive decay - how much is debated, but this alone probably dwarfs humans energy needs (the core of the earth is really, really BIG) The real danger is in creating local earth quakes, because that already happened.

pfdietz 2y ago
Actually, it's estimated radioactive decay in the Earth is about 20 TW, which is also about equal to the current global rate of primary energy consumption. Geothermal can be better described as heat mining than it would be exploiting a steady state heat flow.
xeonmc 2y ago
So essentially : - fusion - power of the Sun - fission - power of the Earth
- antisthenes 2y ago
  No, it's all power of the Sun*. Fissile elements were created by massive star Supernovae elsewhere. Fusion is still the precursor. Except it's very quick catastrophic fusion :)
  - xeonmc 2y ago
    Then: - Fusion - powers the Sun - Fission - powers the Earth
    - rbanffy 2y ago
      Even solar is only indirect fusion. As is wind. Geothermal is... ancient friction combined to fission?

theideaofcoffee 2y ago

More than we could ever hope to extract at even heightened future consumption levels, which you could take to mean pretty much impossible, see a past comment of mine along these lines: [0] [0] https://news.ycombinator.com/item?id=38850786 https://news.ycombinator.com/item?id=38850786

drtgh 2y ago
Thanks. By your link we have a 47TW of annual heat loss from the Earth due to the surface heat flux, that makes 92 KW/Km² annual (Earth is 510M km² [148.9M km² of land]). If the thermal diffusivity can not feed a tinny surface hole more than 20-30 years after extracting just around 3-10 MW, where the sun is supposed to replenish the heat on summer also, what makes the scientific community to have faith the slowness in such thermal diffusivity will not bring consequences? Did anyone study it? ( EDIT: we are talking about more than several centuries, I guess, so my interest decreased proportionally. )

justinpombrio 2y ago

https://en.wikipedia.org/wiki/Geothermal_energy#Resources https://en.wikipedia.org/wiki/Geothermal_energy#Resources

piva00 2y ago

On the phone so won't try to even get to a ballpark but just thinking on the scale we are talking: a massive volume of a molten ball of rock with a thin crust I believe it'd take a fucking lot of energy to have any cooling. Even more where it'd be radiating out to space and "lost".

sfink 2y ago

First, if your extraction method is at all efficient, then much of the energy you extract is going to end up as heat again. Sure, it'll be somewhere it can more easily radiate to space, but rock is a pretty good thermal conductor too. Second, Earth is big. Like, really big. I once did a napkin calculation of the proportional depth of the ocean. How much of a "water world" are we, really? What would it be like for some cosmic being to grab onto the Earth and throw it? Assuming I did it right, the Earth is basically a bowling ball that someone heavily misted with a spray bottle, resulting in an average of 0.4mm of water resting on the ball's surface. (Marianas trench is 6.8 miles deep, diameter of Earth is about 8000 miles, bowling ball is 8.6 inches in diameter. To be fair, that's like 10 squirts of spray.) Said cosmic being would just have to wipe it off with a rag to avoid it slipping out of its hands and accidentally clobbering Alpha Centauri in several years.