Author Topic: What does drilling a Hole for Water cost here in Europe?  (Read 7285 times)

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Online Siwastaja

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #25 on: March 24, 2022, 01:46:41 pm »
Which is (almost certainly) using the ground not as an energy source but as a thermal (energy) storage/"infinite" heatsink, that works great in isolated/sparse areas where the climate annually averages around the "comfortable" indoor temperature.

Exactly.

I don't personally like to use the word "geothermal" because it's confusing and used for different energy sources. Ground-source heatpumping can tap two different sources:
1) Actual geothermal, i.e., heat flow from the molten core of the Earth (by just drilling far enough, or utilizing natural hot water sources). Actual energy source is the massive pool of molten lava, since the Earth was born.
2) Just the thermal storage capacity of the soil or bedrock pretty close to the surface, deep enough so that it follows yearly average climate temperature. Actual energy source is the Sun.

In Northern Finland for example, where air-source heatpumping gets impractical due to significant periods of time below say -20degC air temperature, ground source heatpump installations are used; this would be typically a 150-meter deep well, maybe a bit more. Drilling cost is roughly around 10k€. AFAIK, this is deep enough that the actual geothermal (the lava thing!) shows a tiny contribution, but still it's mostly just averaging the yearly climate, i.e., solar power. Which would be something like +5degC in those areas. Way better for heatpumping than -30degC air!

Accumulating snow works like thermal insulation during winter, so the soil/bedrock temperature is tad higher than you could guesstimate from the yearly average air temperature. So the idea is, maybe the well drilled in bedrock is at +7degC when you start using it during the fall, and maybe it's down to +2degC when you are done in the spring. Then it regenerates for the next winter.

For the energy to regenerate (i.e., the soil needs to heat up again during summer), the well needs to be deep enough, or you need two in parallel, and can't just place them close to each other. Due to the required gaps, this is not THE solution for global energy problems, but it can of course be a small part of it, in sparsely populated, very cold climates - exactly like Northern Finland.

Then again, "true" geothermal works best in areas where you naturally get access to the heated water (hot springs). There, you don't even need heatpumping; temperature could be high enough for passive energy transfer, just pump the water through heat exchangers. It's obvious to utilize this resource to the fullest if you have it, but 99.9999% of people on the planet just won't.
« Last Edit: March 24, 2022, 01:54:20 pm by Siwastaja »
 

Offline NiHaoMike

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #26 on: March 25, 2022, 04:24:36 am »
Short answer is practical storage lifetimes are months/seasonal, and real sites observe this along with changes in ground temperature on the time scales of years:
"Evaluation of Ground Temperature Changes by the Operation of the Geothermal Heat Pump System and Climate Change in Korea"
https://www.mdpi.com/2073-4441/12/10/2931/htm
Put too many users with imbalanced energy demands in the ground and it will cook or freeze (depending on which direction you push the energy), hence it only being practical if balanced or sparse/selfish/tragedy of the commons/ignoring externalities/short term (the opposite of sustainable).
Seems like it should be pretty straightforward to make it balanced if it's well into months or years, use solar thermal collectors to add heat where there's more heating demand than cooling, use radiators to remove heat where there's more cooling demand than heating.
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Offline Someone

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #27 on: March 25, 2022, 05:35:51 am »
Short answer is practical storage lifetimes are months/seasonal, and real sites observe this along with changes in ground temperature on the time scales of years:
"Evaluation of Ground Temperature Changes by the Operation of the Geothermal Heat Pump System and Climate Change in Korea"
https://www.mdpi.com/2073-4441/12/10/2931/htm
Put too many users with imbalanced energy demands in the ground and it will cook or freeze (depending on which direction you push the energy), hence it only being practical if balanced or sparse/selfish/tragedy of the commons/ignoring externalities/short term (the opposite of sustainable).
Seems like it should be pretty straightforward to make it balanced if it's well into months or years, use solar thermal collectors to add heat where there's more heating demand than cooling, use radiators to remove heat where there's more cooling demand than heating.
Hence the free-rider problem if they are densely installed, someone needs to install infrastructure and operate it to do the balancing, but any one individual could just likely ignore it.

1) Actual geothermal, i.e., heat flow from the molten core of the Earth (by just drilling far enough, or utilizing natural hot water sources). Actual energy source is the massive pool of molten lava, since the Earth was born.
Yep, and has exactly the same problem of being a largely uncontrolled public good. When people see "free" energy they suck it up and spend it foolishly, leading to overcorrection in the management such as wide scale closure/capping:
"Effects of Bore Closure at Rotorua, New Zealand"
https://www.geothermal-energy.org/pdf/IGAstandard/Japan/1997/Scott.pdf
 

Online nctnico

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #28 on: March 26, 2022, 08:09:10 pm »
Then again, "true" geothermal works best in areas where you naturally get access to the heated water (hot springs). There, you don't even need heatpumping; temperature could be high enough for passive energy transfer, just pump the water through heat exchangers. It's obvious to utilize this resource to the fullest if you have it, but 99.9999% of people on the planet just won't.
In the end it is a cost versus benefit calculation. You can use geothermal energy in many places; you just need to drill deep enough (2 to 4km) and stay clear from fault lines. In the Netherlands there are about 30 geothermal wells in operation and several  tens more in the planning stage. It looks like most are used to heat greenhouses (to grow crops and flowers) but it could be very useful to heat homes as well through district heating (which is being rolled out in several cities already).
« Last Edit: March 26, 2022, 11:20:00 pm by nctnico »
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Offline MadScientist

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #29 on: March 26, 2022, 08:17:21 pm »
Well drilling is very common here in Ireland , costs about €3000-€9000 for typical potable water drilling lined , excluding pumps and treatments ,   very  dependant on drilling conditions
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Offline Lord of nothingTopic starter

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #30 on: March 28, 2022, 02:43:59 pm »
Quote
the ground water is 8-10'C.
Well I would only order a Company to drill here if the Data show the could find Natural Thermal Water who is way above "normal" Temp here.
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Offline G7PSK

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #31 on: March 29, 2022, 01:19:18 pm »
Quote
the piece of land they own
Theoretical in my Country its not possible to "own" Something since the Gov. can take the Land who you life away and re purpose it. You also have to pay Tax just for "own" a Land who I would say it more pay Rent to the Gov. But beside of that dont be to political. Sure I know I must apply for an Permit but before I drive the Gov. Employee to insanity I would like know if it is affordable enough or so expensive to not think further.
Sorry I have no idea what something could cost. So before I plan way ahead in the Future its good to know if it is just a dream or it could come true.
Thanks  :-+
Here in the UK theoretically  you own the land right down to the centre of the earth, with the catch being if anything valuable is found it belongs to the crown which means you have to pay the government to dig up or otherwise extract what is in the ground you own. You could drill yourself, there are well drilling rigs on Ebay.https://www.ebay.co.uk/itm/274651617730?hash=item3ff28319c2:g:AgMAAOSw~sJgBaqM
« Last Edit: March 29, 2022, 01:34:14 pm by G7PSK »
 

Offline Marco

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #32 on: March 29, 2022, 06:30:51 pm »
"Effects of Bore Closure at Rotorua, New Zealand"
https://www.geothermal-energy.org/pdf/IGAstandard/Japan/1997/Scott.pdf

They could likely have had far greater extraction rates with modern double wall heat exchangers rather than wasteful open systems. Any way, it's ultimately just a question of depth. If you go deep enough the thermal resistance to the core shrinks and the core has defacto infinite energy.
« Last Edit: March 29, 2022, 06:33:47 pm by Marco »
 

Offline Someone

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #33 on: March 29, 2022, 10:02:26 pm »
"Effects of Bore Closure at Rotorua, New Zealand"
https://www.geothermal-energy.org/pdf/IGAstandard/Japan/1997/Scott.pdf
They could likely have had far greater extraction rates with modern double wall heat exchangers rather than wasteful open systems. Any way, it's ultimately just a question of depth. If you go deep enough the thermal resistance to the core shrinks and the core has defacto infinite energy.
Its not infinite, there is a fundamental inflow (flux) of energy available, as fancy as you try to analyse it:
"Longevity and power density of intermediate-to-deep geothermal wells in district heating applications"
https://link.springer.com/article/10.1140/epjp/s13360-021-01094-8
Its still energy in < energy out or you're going to run out. Their simple explanation:
Quote
One of the most important things to keep in mind is that, once the well has been depleted, its rather modest ability to recover leads effectively to a single-use solution unless additional charging is provided. This, however, would merely convert the well from a heat source into a heat storage, incurring additional, perhaps significant electricity costs. Hence, in sizing the well, one should consider choosing a configuration which guarantees a sustainable level of longevity and does not require re-drilling of the bore holes every few years.

Earths radius: 6,378km
Deepest borehole ever: 12km
Its small angle approximation territory, deeper isnt getting access to more flux, just a larger thermal mass (to deplete). No way is this close to infinite energy, current economic extraction is based around years/decades of useful life.
 

Offline Marco

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #34 on: March 29, 2022, 10:41:00 pm »
deeper isnt getting access to more flux
Of course it does, the volume of rock you can steal flux from before it escapes to space grows quadratically with depth.

Depth is a trade off for area.
 

Online nctnico

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #35 on: March 29, 2022, 11:16:38 pm »
deeper isnt getting access to more flux
Of course it does, the volume of rock you can steal flux from before it escapes to space grows quadratically with depth.
Yes and no. At some point you either need insane pressures to prevent the water from boiling from the wall and not getting heated at all. Heating or evaporating a liquid is actually quite an interesting process in itself. Many years ago I worked on a smoke generator that evaporates 'smoke liquid'. You can't keep increasing the temperature to evaporate more liquid. At some point the liquid will form a gas layer between the wall of the heating element and the liquid which prevents heat transfer. The liquid will come out as is; not even very hot.

In practical geothermal systems you see that water gets injected at one point and being pumped up through a different hole. That gives a much larger surface area with a constant temperature compared to a single, deep hole.
« Last Edit: March 29, 2022, 11:26:59 pm by nctnico »
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Offline Marco

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #36 on: March 29, 2022, 11:24:11 pm »
In practical geothermal systems you see that water gets injected at one point and being pumped up through a different hole. That give a much larger surface area with a constant temperature compared to a single, deep hole.

Ignoring practicality for a moment, this ain't going to work for really deep wells. Nothing to pump water through in bedrock, that only works in porous sedimentary rocks and aquifers.

But even with essentially a point source of extraction at the bottom of a well, you will still be stealing flux from a larger top soil surface area the deeper you go.
« Last Edit: March 29, 2022, 11:36:30 pm by Marco »
 

Offline Someone

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #37 on: March 30, 2022, 01:05:08 am »
If you go deep enough the thermal resistance to the core shrinks and the core has defacto infinite energy.
deeper isnt getting access to more flux
Of course it does, the volume of rock you can steal flux from before it escapes to space grows quadratically with depth.

Depth is a trade off for area.
You're arguing sideways....

Its very very simple:
1. assume the majority of the geothermal flux is coming from the core of the earth (you framed this, and its a reasonable measure for generalised geothermal outside the highly active areas)
2. the deepest bore hole ever made ever, 12km, earths radius 6000km. So far from the core its effectively a point source.
3. by going this deep you've increased the flux (W/m2) by 60002/(6000-12)2, 0.4% increase in flux

Yes, you gain access to a larger thermal mass which can have higher extraction ("stealing") power, but the energy coming back in to balance what is being taken out has not increased. Exactly what was said in the paper I linked you to:
"Longevity and power density of intermediate-to-deep geothermal wells in district heating applications"
https://link.springer.com/article/10.1140/epjp/s13360-021-01094-8
Its still energy in < energy out or you're going to run out. Their simple explanation:
Quote
One of the most important things to keep in mind is that, once the well has been depleted, its rather modest ability to recover leads effectively to a single-use solution unless additional charging is provided. This, however, would merely convert the well from a heat source into a heat storage, incurring additional, perhaps significant electricity costs. Hence, in sizing the well, one should consider choosing a configuration which guarantees a sustainable level of longevity and does not require re-drilling of the bore holes every few years.

Trying to claim the first (n) km of the earths depth is radically different in thermal conductivity to the rest is not supported.
 

Offline Marco

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #38 on: March 30, 2022, 02:41:35 am »
1. assume the majority of the geothermal flux is coming from the core of the earth (you framed this, and its a reasonable measure for generalised geothermal outside the highly active areas)

Flux does not go straight up, it follows thermal gradients, the deeper you drill the larger thermal gradients you can create across a larger volume. Or to put it another way, the low temperature spherical disruption of thermal equilibrium around the bottom of the borehole casts a shadow on the surface, the deeper the borehole, the larger the shadow.

You could have say a 10 km deep borehole capture the same flux as 3 3km deep boreholes with 3km between each of them ... the depth can be traded off against area, a single deeper borehole can capture more of the flux across a larger area of the surface.

If you look at figure 2 in the paper you linked you can clearly see it going to an equilibrium after about 200 years, an equilibrium which has to be based on flux and not stored heat. An equilibrium at around a quarter of the initial peak, but still on the same order of magnitude. 0.054 Wm^−2 is small, but with a large enough shadow it can be large enough.
« Last Edit: March 30, 2022, 02:59:52 am by Marco »
 

Offline Someone

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #39 on: March 30, 2022, 04:24:34 am »
1. assume the majority of the geothermal flux is coming from the core of the earth (you framed this, and its a reasonable measure for generalised geothermal outside the highly active areas)

Flux does not go straight up, it follows thermal gradients, the deeper you drill the larger thermal gradients you can create across a larger volume. Or to put it another way, the low temperature spherical disruption of thermal equilibrium around the bottom of the borehole casts a shadow on the surface, the deeper the borehole, the larger the shadow.

You could have say a 10 km deep borehole capture the same flux as 3 3km deep boreholes with 3km between each of them ... the depth can be traded off against area, a single deeper borehole can capture more of the flux across a larger area of the surface.

If you look at figure 2 in the paper you linked you can clearly see it going to an equilibrium after about 200 years, an equilibrium which has to be based on flux and not stored heat. An equilibrium at around a quarter of the initial peak, but still on the same order of magnitude. 0.054 Wm^−2 is small, but with a large enough shadow it can be large enough.
Fig 2 is their example of approaching an equilibrium by limiting the average power extraction. Also note their idea of a lifetime: "time it takes for the system to reach the water inlet–outlet temperature difference of 3 [degrees] C" extremely low grade heat. Its not surprising that they predict lifespans of hundreds of years to draw down several km depth of rock to close to ambient temperature. Seasonal variations disappear after just 10m of depth, so hundreds of years from hundreds of times the depth are right where they would expect to be. Its drawing down on the enormous stored thermal resource and not an infinitely sustainable power draw, just like drawing on fossil fuels, massive stored resource, slowly accumulated.

Humans have been around for 10's of thousands of years, so planning to use up a resource in just hundreds is very short sighted. Might as well suggest once through fission reactors....
 

Offline Lord of nothingTopic starter

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #40 on: March 30, 2022, 08:29:29 am »
 :-\ 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,...
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Offline Marco

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #41 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

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.
« Last Edit: March 30, 2022, 06:39:54 pm by Marco »
 
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Offline Lord of nothingTopic starter

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #42 on: March 30, 2022, 06:52:34 pm »

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?  :-//
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Offline Someone

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #43 on: March 30, 2022, 11:10:24 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
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.

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.
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.
 

Offline Marco

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #44 on: March 30, 2022, 11:22:40 pm »
there is a lot of energy there that can extracted but its not being replenished at the rates you claim are viable/sustainable.
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
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.
« Last Edit: March 30, 2022, 11:32:05 pm by Marco »
 
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Offline Someone

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #45 on: March 30, 2022, 11:25:08 pm »

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?  :-//
So 2W/m/K is close enough and within the error margin, next step is to find what the thermal gradient is. It varies wildly:
"Austria – Country Update" Proceedings World Geothermal Congress 2010
https://www.geothermal-energy.org/pdf/IGAstandard/WGC/2010/0134.pdf
But averages somewhere around 2-3 degrees per 100m, hence the 100mW/m2 figure.

https://en.wikipedia.org/wiki/Earth%27s_internal_heat_budget
 

Offline Someone

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #46 on: March 30, 2022, 11:44:37 pm »
there is a lot of energy there that can extracted but its not being replenished at the rates you claim are viable/sustainable.
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.
Claiming "infinite" energy But you won't quantify the input energy source and flux, sounds like you are the one out on a limb. The average flux is well agreed upon in the scientific community, and is not the same as the possible available flux when given some shorter lifetime. Which is what I already provided a citation for:
"Longevity and power density of intermediate-to-deep geothermal wells in district heating applications"
https://link.springer.com/article/10.1140/epjp/s13360-021-01094-8
Its still energy in < energy out or you're going to run out. Their simple explanation:
Quote
One of the most important things to keep in mind is that, once the well has been depleted, its rather modest ability to recover leads effectively to a single-use solution unless additional charging is provided. This, however, would merely convert the well from a heat source into a heat storage, incurring additional, perhaps significant electricity costs. Hence, in sizing the well, one should consider choosing a configuration which guarantees a sustainable level of longevity and does not require re-drilling of the bore holes every few years.

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
That wasn't my point. The Moho heat flux is 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.
You keep jumping to local/micro effects, and trying to connect them to global/macro effects. Yes, there are sites with highly localised natural radiogenic sources, but they are the exception and not the norm. Start with an average model...

several km boreholes are tiny compared to the 6000km radius of the earth, assuming the energy source is fairly distributed throughout that volume, then you can take a model that ignores the local sources and it becomes a simple infinite surface with energy coming in one side and going out the other. We know what this value is because it has been so carefully studied with both global averages, and extremely detailed local mappings.

A volume of rock has 2.5-3kWh/m3/k energy. For a 10km deep volume that is roughly 25-30MWh of energy per m2 for each degree of change, and its already hot! Yes, heaps of energy just sitting there, you could pull out 100W/m2 for a few decades (matching the above more rigorous model/evaluation). But its only being recharged slowly 100mW/m2 or so.

Have fun discharging your batteries and wondering why they dont refill.
« Last Edit: March 30, 2022, 11:50:54 pm by Someone »
 

Offline Marco

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #47 on: March 31, 2022, 12:05:10 am »
Claiming "infinite" energy But you won't quantify the input energy source and flux
~1 uW/m3 radiogenic heating throughout the entire crust.

But what's the point in knowing that unless you're some 160 IQ genius that you can intuitively use that together with thermal resistances to create a steady state 3D model heat flow model for a deep borehole? Even if you are that 160 IQ genius, I'm not going to just believe that you are on a random internet forum.

Power will flow preferentially to the lower temperature borehole, it does not go straight up as I said before. That's why you need FEM (or 160 IQ) you can't just use the steady state undisrupted straight up thermal flow to determine how much power flows to the borehole.

The borehole attracts power from a wide volume ... how much, hell if I know. The simulation suggests to me, enough.
Quote
several km boreholes are tiny compared to the 6000km radius of the earth
But their size compares a lot better to the depth of the crust.
« Last Edit: March 31, 2022, 12:16:53 am by Marco »
 

Offline Someone

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #48 on: March 31, 2022, 01:30:10 am »
Claiming "infinite" energy But you won't quantify the input energy source and flux
~1 uW/m3 radiogenic heating throughout the entire crust.
Which doesn't match the accepted numbers:
https://en.wikipedia.org/wiki/Earth%27s_internal_heat_budget
Total energy production
47±2 TW 47±2 (terawatts, 1012)
Earths volume
1.1 Zm3 (zetta, 1021)
Average volumetric power
50 nW/m3 (nano, 10-9)
Around half of that being from radiogenic sources:
https://en.wikipedia.org/wiki/Earth%27s_internal_heat_budget#Radiogenic_heat
roughly matching those figures for W/kg.

You keep throwing out figures without anything to back them up, you're starting with ideas (misapplied in their domain/scope) and coming up with incorrect inferences. Trying to just consider the crust (your framing) doesn't make sense when the flow from below dominates, calculate it yourself, even with your alleged much higher radiogenic heat in the crust (which is still much thicker than the practical/economic bore holes so you're back to an infinite plane model).
 
But what's the point in knowing that unless you're some 160 IQ genius that you can intuitively use that together with thermal resistances to create a steady state 3D model heat flow model for a deep borehole? Even if you are that 160 IQ genius, I'm not going to just believe that you are on a random internet forum.

Power will flow preferentially to the lower temperature borehole, it does not go straight up as I said before. That's why you need FEM (or 160 IQ) you can't just use the steady state undisrupted straight up thermal flow to determine how much power flows to the borehole.

The borehole attracts power from a wide volume ... how much, hell if I know. The simulation suggests to me, enough.
Again you're comparing wildly different timeframes and physical scales.

I keep saying it, yes you can pull a whole shit-ton of power out of the earths rocks. But its stored energy that has been collected over geological timeframes. Small energy input over long time. It is possible to pull out a large amount of energy quickly, but thats not sustainable.

The sustainably available energy is well agreed upon, averaging around 100 mW/m2. A number that can be arrived at easily and intuitively from the thermal conductivity and temperature gradient/profile.
 

Offline Marco

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Re: What does drilling a Hole for Water cost here in Europe?
« Reply #49 on: March 31, 2022, 01:51:24 am »
Which doesn't match the accepted numbers:
Because it's generated mostly in the crust and you're comparing it against the total volume of the planet.
Quote
I keep saying it, yes you can pull a whole shit-ton of power out of the earths rocks. But its stored energy that has been collected over geological timeframes.
Prove it by modeling, to my eyeballs the steady state extraction for the borehole modelled and measured suggests stabilization in decades, not eons.
Quote
The sustainably available energy is well agreed upon, averaging around 100 mW/m2. A number that can be arrived at easily and intuitively from the thermal conductivity and temperature gradient/profile.
Yes, if you put a ton of horizontal pipe near the surface that's the power you can extract from near the surface given the area covered by the horizontal pipeline field (though usually near the surface ground water will do a lot of the heavy lifting for you increasing the effective area). With deep boreholes you trade off area for depth though. It will pull in thermal power from a wide volume and create an expanding plume of lower temperature towards the surface. A single deep borehole is equivalent to a large horizontal pipeline field near the surface.

The steady state size and temperature of that plume near the surface relative to baseline would also let you calculate how much energy it extracts in steady state. But it would still take FEM or 160 IQ to determine exactly ... all I can say is that it almost certainly increases quadratically with depth.
« Last Edit: March 31, 2022, 02:18:11 am by Marco »
 


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