What does drilling a Hole for Water cost here in Europe? - Page 1
Forum section: electronics / general

author: Lord of nothing
author_rank: Super Contributor
timestamp: March 22, 2022, 06:28:43 pm
content: HiLong story Short here in Vienna we have a Thermal Bath where the Hot Water was found by accident during an search for Natural Oil. Wikipedia say the drill 900m deep:https://de.wikipedia.org/wiki/Therme_WienSo I life on the other side of my City and I asked my selfwhat does such a drilling would cost?If here in the same depth hot Water would be found it would mean "free" Heating for the next Century and free Water.Does someone know it or maybe done if before?Thanks

author: rstofer
author_rank: Super Contributor
timestamp: March 22, 2022, 06:55:16 pm
content: We produce a TON of electricity from geothermal sources:https://en.wikipedia.org/wiki/Geothermal_powerI would think that drilling to these depths would be prohibitive for individuals. I have been told that the steam/water is quite corrosive and that creates another constraint.Our water well is 300 feet deep and newer wells are drilling to 1000 feet. Right now, the water level is at 200 feet so we're ok, for a while. I don't look forward to drilling further.Gas and oil wells can go to 30,000 feet - that's a hike!https://www.aeraenergy.com/anatomy-of-an-oil-well

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 22, 2022, 07:20:04 pm
content: Quote from: rstofer on March 22, 2022, 06:55:16 pmNot only that, but if you're talking about individuals drilling the piece of land they own, that would just be illegal in many countries. Depending on local regulations, the "depth" of land you own is very variable, but often pretty limited.

author: Lord of nothing
author_rank: Super Contributor
timestamp: March 22, 2022, 08:26:44 pm
content: QuoteTheoretical 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

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 22, 2022, 09:15:41 pm
content: I can't speak to costs in your area. Drilling costs always vary wildly with the material being drilled, the size of the hole and required liner. Obviously hard rock (taconite for example) is worse than sandstone and best case is loess soils found in some locations to the depths you mention.Here in the US a ball park figure for a six inch (12 cm) borehole with a liner appropriate for domestic water would be $25/ft or about $75/meter. But that is a very large ball park. I would not be surprised at values 3-4 times larger or a factor of 2-3 smaller. Doing lining and or plumbing for a hydrothermal system would undoubtedly be higher, and I believe for this type of things costs in western Europe tend to be a bit higher.

author: themadhippy
author_rank: Super Contributor
timestamp: March 22, 2022, 09:56:24 pm
content: You got an sds drill? inch x 1 meter long drill bit at £15 and 899 1 meter extension rods at around a tenner each,so about £9k ,plus the leccy for your drill.

author: Sal Ammoniac
author_rank: Super Contributor
timestamp: March 22, 2022, 10:52:32 pm
content: Our well is 375 feet deep and it's been a dry hole for the past several years due to the drought in California. My well guy says he can dig another well, even deeper, for about USD$60,000 with no guarantee he'll hit water.

author: SmallCog
author_rank: Frequent Contributor
timestamp: March 23, 2022, 03:27:42 am
content: I can't speak for European prices but in Australia we wouldn't drill and case (line) a single shallow water bore for less than $10,000 but if you wanted a few of them near each other, or a bunch of neighbors all wanted them at the same time, that could bring prices down.Irrespective of the cost to do the actual drilling (typically charged per meter) there's all the fixed costs related to millions of dollars worth of equipment, staff, etc.Getting to about 100m would run you closer to $20,000 and be about 2 days work.900m can be reached with a large mostly self contained truck mounted rig, but it's unlikely to be able to be drilled with compressed air so the rig will need mud pits. These can either be swimming pool sized holes dug in the land or be large tanks brought to site. The work area will need to be around 20x20m minimum with clear access for heavy vehicles and no neighbors to complain about the noise (there'll be lots)There'll be a lot of spoil to be disposed of, it might only be quite narrow but you are digging a hole to 900m deep and it will add up. On a drill pad (area) the size about there wont be space for all of it and it will need to be taken away in trucks. I'm not costing this in my estimate belowThe deeper you go the fancier the caseing (liner) of your drill hole needs to be to withstand the forces in the earth, this may end up costing as much as the drilling.It would be somewhere around $750,000 if my former employer drilled and cased your hole in Australia, and that's only if the ground was favourable. If it was unfavourable ground we'd pass on a job like that - too much risk of things going wrong, taking too long, and costing us money given we would be charging by the meter on completion.We actually got enquiries in regards to things like this on a semi regular basis from well meaning people who had no idea how tricky it was to do :-)

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 23, 2022, 03:56:32 am
content: Here's a long thread about DIY drilling shallow wells for a DIY geothermal heat pump:https://ecorenovator.org/forum/showthread.php?t=484Drilling deep wells is a lot more difficult.

author: Someone
author_rank: Super Contributor
timestamp: March 23, 2022, 06:14:18 am
content: Quote from: rstofer on March 22, 2022, 06:55:16 pmCompared to other sources geothermal is still a tiny tiny speck of US production around 1% of electricity or 0.3% total:https://www.iea.org/sankey/#?c=United%20States&s=Balancewhich is behind the world average of 1.5% of electricity and 0.5% total:https://www.iea.org/sankey/#?c=World&s=BalanceSo yeah, "we" produce a pitiful amount of geothermal energy, and its source/supply is extremely limited compared to alternatives:https://www.withouthotair.com/c16/page_97.shtmlmW per square meter!Quote from: Lord of nothing on March 22, 2022, 06:28:43 pmLong term production depends on how quickly you pull down on the stored energy, geothermal sources tend to get "used up" in short periods of time years/decade.

author: Mazo
author_rank: Regular Contributor
timestamp: March 23, 2022, 08:35:44 am
content: Just a reference number,a buddy of mine had a hole drilled in afaik not that bad soil for drilling.30m hole=1500EUR,so 50EUR per m.In Bulgaria.Not a drop of water unfortunately.

author: nctnico
author_rank: Super Contributor
timestamp: March 23, 2022, 08:54:39 am
content: Quote from: Someone on March 23, 2022, 06:14:18 amUnfortunately that article got the numbers all messed up.https://en.wikipedia.org/wiki/Geothermal_energysays that between 2MW and 10MW can be produced per well.

author: Lord of nothing
author_rank: Super Contributor
timestamp: March 23, 2022, 09:27:39 am
content: I would use a Heat exchanger or so.Sure I would depend what the Mixture is and if the Water is consumable "fresh" out of the Hole.I dont know if any Values are over the Limit like Sulfure, Lead,... or what ever could come out from the Core of the Earth.

author: Miyuki
author_rank: Frequent Contributor
timestamp: March 23, 2022, 09:36:27 am
content: There is an issue with deep drilling. You can cause loss of water in other wells, even kilometers away. By accidentally puncturing some deep layers.And then you are liable for the losses. You do not want to be in this situation.btw for water, I use an old dug well, it is really old and has water at about 10m level. It must be a hell of a work to dig it back in the day without power tools.

author: Lord of nothing
author_rank: Super Contributor
timestamp: March 23, 2022, 10:02:04 am
content: I guess there are no other commercial used Wells in my Area.

author: Someone
author_rank: Super Contributor
timestamp: March 23, 2022, 10:22:56 am
content: Quote from: nctnico on March 23, 2022, 08:54:39 amGeothermal energy is not evenly distributed, highly productive wells are the anomalies. Peak power generation is not addressing the energy/lifespan issues of geothermal. A more on topic wikipedia page has the salient quote that although there is power, its uneconomic/impractical to harvest:Quote from:https://en.wikipedia.org/wiki/Geothermal_powerLow-grade heat has its purposes, but its not a widely exploitable and magic source of useful energy.

author: langwadt
author_rank: Super Contributor
timestamp: March 23, 2022, 01:03:05 pm
content: Quote from: Someone on March 23, 2022, 10:22:56 amhere there is an office building that uses an old well with too much nitrate for human consumption for cooling in the summer and via a heatpump heating in winter

author: Someone
author_rank: Super Contributor
timestamp: March 23, 2022, 09:08:10 pm
content: Quote from: langwadt on March 23, 2022, 01:03:05 pmWhich 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. When imbalanced it doesnt last forever and isnt as "infinite" as people think:https://en.wikipedia.org/wiki/London_Underground_coolingas a utility/storage method it doesnt scale up to mid-desnity suburbs:https://www.withouthotair.com/cE/page_302.shtmlAre you going to be the one putting energy in for the other users? a massive free-rider problem on that.

author: nctnico
author_rank: Super Contributor
timestamp: March 23, 2022, 10:28:03 pm
content: Quote from: Someone on March 23, 2022, 10:22:56 amAgain, you are not reading carefull enough: 0.1W/m2 is what is being radiated to the earths surface into space. Which is why you need to drill a deep hole in order to get closer to the core to circumvent the insulation of the earth's crust.

author: nctnico
author_rank: Super Contributor
timestamp: March 23, 2022, 10:33:04 pm
content: Quote from: Lord of nothing on March 23, 2022, 09:27:39 amCount on the water being non-potable.Quote from: Miyuki on March 23, 2022, 09:36:27 amThat is a serious concern indeed. The first thing to find out is whether you can get a permit to drill a well. In some places there are ancient natural water reservoirs that need to remain untouched.

author: langwadt
author_rank: Super Contributor
timestamp: March 23, 2022, 11:02:17 pm
content: Quote from: Someone on March 23, 2022, 09:08:10 pmthe ground water is 8-10'C. When used for cooling you could call it a heatsink, when used for heating it is a heat source for the heat pump

author: Someone
author_rank: Super Contributor
timestamp: March 24, 2022, 01:03:20 am
content: Quote from: nctnico on March 23, 2022, 10:28:03 pmSure go deep, its hot down there, but you're depleting the stored energy. Which is why practical geothermal plants move the extraction wells around as they deplete.Or are you going to try and argue the 100mW/m2flux at the surface is hiding some other mechanism (the earths core is increasing in temperature over time?). Rather:Quote from:https://en.wikipedia.org/wiki/Geothermal_gradientQuote from:https://en.wikipedia.org/wiki/Geothermal_gradientSo what replaces that energy you take out? Or is cooling the core of the earth going to have zero side effects? lolol.

author: Someone
author_rank: Super Contributor
timestamp: March 24, 2022, 01:06:14 am
content: Quote from: langwadt on March 23, 2022, 11:02:17 pmSo its likely with that imbalance of thermal demand that they are drawing down on the thermal store and it will cool down. Why are you all railing against this simple concept? Yes, its hot, but if you use that energy it is replaced very slowly.

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 24, 2022, 02:31:24 am
content: Quote from: Someone on March 24, 2022, 01:06:14 amHow long is the time constant? If it's on the order of days or weeks or more, it could make sense to "recharge" it with solar thermal.

author: Someone
author_rank: Super Contributor
timestamp: March 24, 2022, 07:07:10 am
content: Quote from: NiHaoMike on March 24, 2022, 02:31:24 amIts not a simple as a time constant, think a sum of infinite time constants like the model for dielectric absorption (spreading further and further into the volume). 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/htmPut 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 balancedorsparse/selfish/tragedy of the commons/ignoring externalities/short term (the opposite of sustainable).

author: Siwastaja
author_rank: Super Contributor
timestamp: March 24, 2022, 01:46:41 pm
content: Quote from: Someone on March 23, 2022, 09:08:10 pmExactly.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 followsyearlyaverage 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.

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 25, 2022, 04:24:36 am
content: Quote from: Someone on March 24, 2022, 07:07:10 amSeems 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.

author: Someone
author_rank: Super Contributor
timestamp: March 25, 2022, 05:35:51 am
content: Quote from: NiHaoMike on March 25, 2022, 04:24:36 amHence the free-rider problem if they are densely installed,someoneneeds to install infrastructure and operate it to do the balancing, but any one individual could just likely ignore it.Quote from: Siwastaja on March 24, 2022, 01:46:41 pmYep, 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

author: nctnico
author_rank: Super Contributor
timestamp: March 26, 2022, 08:09:10 pm
content: Quote from: Siwastaja on March 24, 2022, 01:46:41 pmIn 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).

author: MadScientist
author_rank: Frequent Contributor
timestamp: March 26, 2022, 08:17:21 pm
content: 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

author: Lord of nothing
author_rank: Super Contributor
timestamp: March 28, 2022, 02:43:59 pm
content: QuoteWell 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.

author: G7PSK
author_rank: Super Contributor
timestamp: March 29, 2022, 01:19:18 pm
content: Quote from: Lord of nothing on March 22, 2022, 08:26:44 pmHere 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

author: Marco
author_rank: Super Contributor
timestamp: March 29, 2022, 06:30:51 pm
content: Quote from: Someone on March 25, 2022, 05:35:51 amThey 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.

author: Someone
author_rank: Super Contributor
timestamp: March 29, 2022, 10:02:26 pm
content: Quote from: Marco on March 29, 2022, 06:30:51 pmIts 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/s13360-021-01094-8Its still energy in < energy out or you're going to run out. Their simple explanation:QuoteEarths radius: 6,378kmDeepest borehole ever: 12kmIts 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.

author: Marco
author_rank: Super Contributor
timestamp: March 29, 2022, 10:41:00 pm
content: Quote from: Someone on March 29, 2022, 10:02:26 pmOf 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.

author: nctnico
author_rank: Super Contributor
timestamp: March 29, 2022, 11:16:38 pm
content: Quote from: Marco on March 29, 2022, 10:41:00 pmYes 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.

author: Marco
author_rank: Super Contributor
timestamp: March 29, 2022, 11:24:11 pm
content: Quote from: nctnico on March 29, 2022, 11:16:38 pmIgnoring 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.

author: Someone
author_rank: Super Contributor
timestamp: March 30, 2022, 01:05:08 am
content: Quote from: Marco on March 29, 2022, 06:30:51 pmQuote from: Marco on March 29, 2022, 10:41:00 pmYou'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 fluxYes, 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:Quote from: Someone on March 29, 2022, 10:02:26 pmTrying to claim the first (n) km of the earths depth is radically different in thermal conductivity to the rest is not supported.

author: Marco
author_rank: Super Contributor
timestamp: March 30, 2022, 02:41:35 am
content: Quote from: Someone on March 30, 2022, 01:05:08 amFlux 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.

author: Someone
author_rank: Super Contributor
timestamp: March 30, 2022, 04:24:34 am
content: Quote from: Marco on March 30, 2022, 02:41:35 amFig 2 is their example ofapproachingan 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  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....

author: Lord of nothing
author_rank: Super Contributor
timestamp: March 30, 2022, 08:29:29 am
content: 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,...

author: Marco
author_rank: Super Contributor
timestamp: March 30, 2022, 06:07:40 pm
content: Some more simulations based on heatflux boundary conditions :https://mdpi-res.com/d_attachment/energies/energies-13-00754/article_deploy/energies-13-00754.pdfSeems 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.

author: Lord of nothing
author_rank: Super Contributor
timestamp: March 30, 2022, 06:52:34 pm
content: 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?

author: Someone
author_rank: Super Contributor
timestamp: March 30, 2022, 11:10:24 pm
content: Quote from: Marco on March 30, 2022, 06:07:40 pmThat 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 pmNatural 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 slowtime 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.

author: Marco
author_rank: Super Contributor
timestamp: March 30, 2022, 11:22:40 pm
content: Quote from: Someone on March 30, 2022, 11:10:24 pmI 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.QuoteThat 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.

author: Someone
author_rank: Super Contributor
timestamp: March 30, 2022, 11:25:08 pm
content: Quote from: Lord of nothing on March 30, 2022, 06:52:34 pmSo 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 2010https://www.geothermal-energy.org/pdf/IGAstandard/WGC/2010/0134.pdfBut averages somewhere around 2-3 degrees per 100m, hence the 100mW/m2figure.https://en.wikipedia.org/wiki/Earth%27s_internal_heat_budget

author: Someone
author_rank: Super Contributor
timestamp: March 30, 2022, 11:44:37 pm
content: Quote from: Marco on March 30, 2022, 11:22:40 pmClaiming "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:Quote from: Someone on March 29, 2022, 10:02:26 pmQuote from: Marco on March 30, 2022, 11:22:40 pmYou 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 m2for each degree of change, and its already hot! Yes, heaps of energy just sitting there, you could pull out 100W/m2for a few decades (matching the above more rigorous model/evaluation). But its only being recharged slowly 100mW/m2or so.Have fun discharging your batteries and wondering why they dont refill.

author: Marco
author_rank: Super Contributor
timestamp: March 31, 2022, 12:05:10 am
content: Quote from: Someone on March 30, 2022, 11:44:37 pm~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.QuoteBut their size compares a lot better to the depth of the crust.

author: Someone
author_rank: Super Contributor
timestamp: March 31, 2022, 01:30:10 am
content: Quote from: Marco on March 31, 2022, 12:05:10 amWhich doesn't match the accepted numbers:https://en.wikipedia.org/wiki/Earth%27s_internal_heat_budgetTotal energy production47±2 TW 47±2 (terawatts, 1012)Earths volume1.1 Zm3(zetta, 1021)Average volumetric power50 nW/m3(nano, 10-9)Around half of that being from radiogenic sources:https://en.wikipedia.org/wiki/Earth%27s_internal_heat_budget#Radiogenic_heatroughly 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).Quote from: Marco on March 31, 2022, 12:05:10 amAgain 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.

author: Marco
author_rank: Super Contributor
timestamp: March 31, 2022, 01:51:24 am
content: Quote from: Someone on March 31, 2022, 01:30:10 amBecauseit's generated mostly in the crustand you're comparing it against the total volume of the planet.QuoteProve it by modeling, to my eyeballs the steady state extraction for the borehole modelled and measured suggests stabilization in decades, not eons.QuoteYes, 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.

author: nctnico
author_rank: Super Contributor
timestamp: March 31, 2022, 01:56:32 am
content: This discussion is starting to run in circles

author: Someone
author_rank: Super Contributor
timestamp: March 31, 2022, 02:59:00 am
content: Quote from: Marco on March 31, 2022, 01:51:24 amWhich is why its easiest to normalise everything to surface area, mW/m2Yes, you can use a deep well to pull more power over a larger area and/or volume, but the incoming energy source is well known to be limited per uint of area as its almost entirely coming from below.Quote from: nctnico on March 31, 2022, 01:56:32 amI just see someone coming back time and time again with outrageous/misleading/bonkers claims who won't even look at the established figures or simple models. If most of the geothermal energy sources were distributed through the crust then it wouldn't have a linear temperature vs depth profile, but almost everywhere does have a close to linear gradient.Using an electrical equivalent model its a classic transmission line, distributed resistance (thermal conductivity) and capacitance (thermal mass). When you run the numbers on such a model you see a tiny little current source at one end (the thermal energy coming up from deeper within the earth) and a huge amount of capacitance along the way to the surface.Like a railgun, massive short term power available, but recharging takes a long time.

author: Marco
author_rank: Super Contributor
timestamp: March 31, 2022, 03:38:55 am
content: Quote from: Someone on March 31, 2022, 02:59:00 amWhich requires quite complex FEM modelling or 160 IQ intuition to actually do. You don't currently have any real model either, just lots of talk and some intuition.QuoteIt looks linear to the depth we can drill ... which isn't all that deep.With enough assumptionsmatching measurements with the accepted levels of radiogenic heating isn't a big problem.It's accepted science that radiogenic heating makes up a large part of the heat flux in the crust,the paper I linkedhas plenty of references if you want them. This isn't fringe science, it's just a corner of science which escaped your attention before.QuoteTalk and intuition.An excerpts from the above paper :Quote

author: Someone
author_rank: Super Contributor
timestamp: March 31, 2022, 05:01:59 am
content: Quote from: Marco on March 31, 2022, 03:38:55 amBut we're talking about geothermal energy extraction with wells wecandrill, which as I said reach depths where approximations to the models are valid. I provided the links to the FEM modelling paper which does all the fancy stuff and still predicts close to a trivial model (one single storage with one input and output).Quote from: Marco on March 31, 2022, 03:38:55 amEven if half the energy comes from the crust (as example: "Controls of Radiogenic Heat and Moho Geometry on the Thermal Setting of the Marche Region (Central Italy): An Analytical 3D Geothermal Model"https://www.mdpi.com/1996-1073/14/20/6511) it doesn't change the fundamental limit of the surface flux. If you pull more than the surface flux out of the area, you are reducing the temperature of the thermal storage. Unless you want to argue that we have an imbalance of thermal flux and the earths core is currently increasing in temperature, then all (100%) of the thermal energy produced (from any depth) is released as the surface flux.Yes you can have a deep well and suck up heaps of power, but thats flux thatdoesn'tcome up where it used to. Hence sticking to mW/m2as the measure of available sustainable resource. Which the paper you link to here leads with as Fig 1. Its not surprising they can point to locations with high crustal activity and low flux across the Moho discontinuity, such as the South Australian Heat FlowAnomaly. But the sustainable power production is still 100mW/m2(even in that unusual and "highly active" [for the geological age] region)

author: Marco
author_rank: Super Contributor
timestamp: March 31, 2022, 05:33:29 am
content: Quote from: Someone on March 31, 2022, 05:01:59 amPulling less than the available surface area worth of flux in a region is good enough for lesser populated countries.In my country not so much, but all the large geothermal systems in my country have to operate at yearly net 0 extraction.QuoteSo the frost line goes a little deeper.For the theoretical 20 km deep boreholes, would it really matter if say 2000 km2 of desert soil gets its flux cut in half to run a 100 MW power plant

author: Someone
author_rank: Super Contributor
timestamp: March 31, 2022, 06:16:37 am
content: Quote from: Marco on March 31, 2022, 05:33:29 amProbably wouldn't matter with the slow energy removal and ground cooling being barely noticeable on a human time scale. Even with the 2-3km as modelled above you can pull out 10-20x the surface flux and be out in the thousands of years timeframe for lifetime/side effects.

author: nctnico
author_rank: Super Contributor
timestamp: March 31, 2022, 12:56:46 pm
content: Quote from: Someone on March 31, 2022, 02:59:00 amThat doesn't really matter. You have to look at the practical side too. A well won't have an eternal lifetime due to material deterioration. As usual it is a cost versus benefit trade-off. That is what the reports are all about: providing information to assess energy production versus time so people can determine ROI. Having a well that produces for 30 to 50 years is more than long enough. By then technology will have advanced so much that the economics and technologies used are totally different.

author: Someone
author_rank: Super Contributor
timestamp: March 31, 2022, 09:50:34 pm
content: Quote from: nctnico on March 31, 2022, 12:56:46 pmRedrilling a well into a still productive resource is in no way equivalent to leaving an area denuded of thermal energy and going somewhere else. Current "shallow" geothermal plants are sometimes run in that regime, but being shallow they are leaving those areas to recover over human scale periods (hundreds of years) and:long term extraction is still limited by the surface flux (where this keeps coming around and around to, fundamental energy in vs energy out).When talking about deep/large volume extraction its leaving larger and longer lasting legacies. Major cities have histories of hundreds to thousands of years, but thermal energy distribution is more expensive and lossy than electricity (district heating) so it needs to be close to the consumer. Like rubbish dumps, thermal extraction leaves geological problems that need to be worked around. Feel free to pick a lifetime you think is reasonable, but I say anything less than 1000 years is short sighted given how cities tend to stay around longer than that. Intentionally going in with the plan to use all the stored resource in the material lifespan of the well/plant is roughly as sustainable as fossil fuels (completely not sustainable). You can promote selfish solutions all you like, and I'll keep pointing it out for what it is. The IPCC recognise this:" Energy Systems. In: Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change"Quote from:https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_chapter7.pdfGeothermal energy can be sustainable, but much of it isnt, yet people get all warm and fuzzy about it being zero carbon and "green". There is a geological time scale store of energy that could be exploited for short term gain, just like fossil fuels, the rate of replenishment is very slow (replenishment rate of fossil fuels seems to be hard to find!).

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 31, 2022, 10:17:21 pm
content: While I agree philosophically about the concept of overusing a geothermal resource, rough numbers don't seem to make it a likely problem. The time constants required to make extraction workable seem to make recovery relatively short term. I haven't been able to come up with solid numbers, but they are definitely knowable. Deep diamond mines have been extracting heat for decades, not for use at the surface but to make the mines marginally habitable for the miners. The cost of such extraction should be well known and if there is significant depletion should show a distinct decline over time. There are other similar sources of hard data.