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Cape Station, future home of an enhanced geothermal power plant, in Utah

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177 points mooreds | 6 comments | 06 Sep 25 20:26 UTC | HN request time: 0s | source | bottom
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its-kostya ◴[06 Sep 25 21:13 UTC] No.45152894[source]▶
Today I discovered that geothermal energy is a thing, cool! An immediate question that comes to mind is how much "energy potential" does the earth store and "how is it generated"? I'd imagine something about gravity or magnetic waves that move the iron* core and stuff. Anyone know some resources I can read more about this?
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giggyhack ◴[06 Sep 25 21:19 UTC] No.45152938[source]▶
Assuming we can drill deep enough and harness it, the thermal energy in the earth's crust is essentially infinite.
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bbarnett ◴[06 Sep 25 21:23 UTC] No.45152975[source]▶
People said "the Earth is too big, human activity can't change the climate". Now look at where we are.

I wonder, if we draw enough heat out... would the core cool enough to shrink? And if so, would the crust collapse to the new size?

Pure speculation of course, but did the first guy burning coal know the outcome?

Anyhow, I love geothermal, think you're right, but just got tweaked on the word "infinite".

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thehappypm ◴[06 Sep 25 21:35 UTC] No.45153071[source]▶
Just some rough physics..

Q = m c ΔT

m = mass of the crust (roughly 10^22 kg)

C = specific heat of crust (roughly 1000 J/kg·K)

ΔT = 1 K

Q = 10^25 joules would be needed to lower the earths crust by 1 degree K

About 10,000 years worth of today’s human energy consumption

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conditionnumber ◴[06 Sep 25 21:56 UTC] No.45153242[source]▶
I wonder how much ΔT you need at the crust to meaningfully change Earth's magnetic field by altering convection patterns in the outer core. I don't know enough physics to attempt an answer.
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1. aDyslecticCrow ◴[06 Sep 25 22:20 UTC] No.45153418[source]▶
Calculating or simulating how earths magnetic field behaves or is generated is quite a complex task. So im doubtful we can usefully estimate it to such precision. It would be interesting though.
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2. hollerith ◴[06 Sep 25 22:29 UTC] No.45153491[source]▶
We know that if the convection in the outer core stops, the Earth's magnetic field stops, and removing enough heat from the core will stop the convection.
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3. aDyslecticCrow ◴[06 Sep 25 22:34 UTC] No.45153528[source]▶
Yes but calculating the energy draw required for any measurable change in this effect is very different from knowing the rough process it operates on.

We know how weather works quite well, but knowing if it will rain in a week is an entirely different beast.

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4. hollerith ◴[06 Sep 25 23:10 UTC] No.45153751{3}[source]▶
I've seen a confident estimate in the form of a calculation. They know what kind of compounds (term?) are in the outer core and they know the minimum temperature those compounds need to be at to be free-flowing enough to sustain the field. And I'm pretty sure we know the current temperature of the outer core.

My memory is that the calculation found that if humanity switched to geothermal for all its energy needs, then in only about 1000 years, the core cools enough for the magnetic field to stop, but I am not sure.

(We should definitely deploy geothermal in the Yellowstone caldera though long enough to cool it down enough so that it will not erupt again.)

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5. hexpeek ◴[06 Sep 25 23:55 UTC] No.45153977{4}[source]▶
Whoa, this is a bit scary. As mentioned earlier, it should basically be used in a way where other energy sources are tapped first, and only the shortfall is covered.
6. lazide ◴[07 Sep 25 01:14 UTC] No.45154405{4}[source]▶
That is definitely not true hahaha. The outer core is several thousand km down, and the crust is only 30km thick. And we have the entire mantle below us.

Humanity could max out geothermal for a million years and never make a dent.