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What does drilling a Hole for Water cost here in Europe?
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Lord of nothing:
 :-\ When I see how much Ice Cold Air must be pumped into a Mine to get them down to a Temp. who is ok to work in I see there must be a lot of energy there. Beside of that a 10km deep Hole is nothing I would drill with an classic System more with something a Vertical TBM who is self contained (beside some consumable like Water, Power, Air,...
Marco:
Some more simulations based on heatflux boundary conditions :

https://mdpi-res.com/d_attachment/energies/energies-13-00754/article_deploy/energies-13-00754.pdf

Seems to me there is sufficient energy to extract economically even in steady state, if you want high grade heat you will obviously have to get far deeper ... but that's where the RF drilling experiments come in.

PS. most heat flux in the ground is actually not from the core, most is radiogenic heating inside the crust. Heat has to come from far to replenish the borehole, but not necessarily as far as you think.
Lord of nothing:

From my City I found that Information maybe someone can translate it:
<200m Berechnete konduktive Wärmeleitfähigkeit 0-200 m = 2 W/m/K (+/- 0,2 W/m/K)
<100m Berechnete konduktive Wärmeleitfähigkeit 0-100 m = 1,95 W/m/K (+/- 0,2 W/m/K)
<30m   Berechnete konduktive Wärmeleitfähigkeit 0-30 m = 1,85 W/m/K (+/- 0,2 W/m/K)

Maybe someone can say something about the numbers. Maybe below 200m it get hotter?  :-//
Someone:

--- Quote from: Marco on March 30, 2022, 06:07:40 pm ---Some more simulations based on heatflux boundary conditions :

https://mdpi-res.com/d_attachment/energies/energies-13-00754/article_deploy/energies-13-00754.pdf
--- End quote ---
That does a much better job of illustrating how/why higher power can be extracted with deeper wells, but nothing supporting the sustainability of higher power extraction.


--- Quote from: Marco on March 30, 2022, 06:07:40 pm ---Seems to me there is sufficient energy to extract economically even in steady state, if you want high grade heat you will obviously have to get far deeper ... but that's where the RF drilling experiments come in.

PS. most heat flux in the ground is actually not from the core, most is radiogenic heating inside the crust. Heat has to come from far to replenish the borehole, but not necessarily as far as you think.
--- End quote ---
Natural radiogenic resources are nifty too, and there are some exploitable resources scattered around the world. But as with thermal leakage from the earths core, it has been collected into the enormous thermal reservoir that is the earths mass, there is a lot of energy there that can extracted but its not being replenished at the rates you claim are viable/sustainable.

A lumped capacitance model captures all this fairly well (you can assume an infinite flat field being uniformly heated and extracted), where there is some energy coming in from the core and other ground based sources. Easily observable are the thermal gradient, seasonal lag, extremely slow time constants when shifting energy around through the ground over km distances, and the huge amount of thermal mass which makes that work.

The thermal gradient is the basic calculation of what the available flux is, we can measure the grounds thermal conductivity and the temperature gradient fairly accurately (as above). Leaving the steady state flux as known, pull out more than that and you will deplete the (massive) thermal storage.
Marco:

--- Quote from: Someone on March 30, 2022, 11:10:24 pm ---there is a lot of energy there that can extracted but its not being replenished at the rates you claim are viable/sustainable.

--- End quote ---
I think the onus to prove that is on you.

There's decade level simulations which certainly seem to level off to an usable steady state from which I'm extrapolating ... I obviously haven't run the simulation to centuries, but still it's what I have to eyeball. In the absence of numbers I'll trust my eyeballs in this.

--- Quote ---Natural radiogenic resources are nifty too, and there are some exploitable resources scattered around the world. But as with thermal leakage from the earths core
--- End quote ---
That wasn't my point. The Moho heat flux is far lower than upper crust heat flux for pretty much all continental crust. Thermal leakage from the core is not the main process heating up the crust, radiogenic heating is, everywhere on land.
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