9 ms·

Geothermal's path to relevance: cheap drilling

153 points by drocer88 5y ago

phreeza 5y ago
I am always a bit bearish on geothermal, because the energy flow through the earths crust is just so damn low. Per surface area, it is about 3 orders of magnitude less than solar irradiation, which means that the circumstances in which it really makes sense to exploit geothermal are those where you can effectively harvest flows from a much larger area, most likely due to convection of water or magma. My understanding is that it will never make sense for e.g. every house in a suburban setting to have their own heat probe and pull energy from that, they will be competing with their neighbors and effective energy gained will be negligible.
- streamofdigits 5y ago
  is surface area a fair comparison? A deep well should be able to extract all along its length
  - cdeonier 5y ago
    How does a deep well extract all along its length? My belief was the production well will experience a gradient (so the bottom of the well will have the temperature you need), and the temperature will drop as you get closer to the surface (which also contributes to the calcite scaling problem geothermal can experience). Also, I think a lot of wells add concrete casing (or metal, as indicated in the article) around portions of the well, which would prevent extraction around those zones of the well.
    - streamofdigits 5y ago
      assuming you can reach a working temperature differential why not continue deeper with the well? From that threshold depth onwards you can extract heat along a line segment that extends to the ultimate depth (which is pressumably dictated by engineering limitations) caveat: thinking like a physicist, not an engineer :-)
- Retric 5y ago
  It’s often less about the heat flow than simply the amount of heat contained in that volume of rock. For your example: A 1/2 acre home is 2023 m2, 1kg of rock is ~2000j/degrees Celsius, 1 cubic meter of rock is ~2500 kg, down 1k = ~2000 j * 2500 * 2023 * 1000 / 60 / 60 / 1000 ~= 2,800,000 kWh per degC. If you’re talking 1kw of heat on average from that rock you only drop 1 degree after 300 years. Of course 1km is a fairly deep, but if you’re using a heat pump chances are you’re averaging much less than 1kw over the entire year.
  - phreeza 5y ago
    Thanks that is a great point I hadn't considered. I suppose strictly speaking it is not renewable when you use it like that, but still pretty clean.
  - kragen 5y ago
    This is totally irrelevant to anything in the article, except in the sense that both pertain to thermal energy and the earth. They have nothing else in common. You can't run a factory, a computer, or a car off a ground-source heat pump, because heat pumps consume energy; they don't produce it.
    - Retric 5y ago
      Most of that post had nothing to do with heat pumps, however digging 1km down for a single family home is generally a poor method of extracting energy from the earth as it can be as little as 6C and is only 25C on average above ambient temperature. Much higher ground temperatures are of course useful to create electricity, but such systems are best centralized not used for single family homes. Also, as a centralized system it’s volume is arbitrary. In the north that 6-25C can still make heat pumps vastly more efficient, but you’re extracting energy and cooling that down over time. Which is why it is relevant to the discussion.
      - kragen 5y ago
        I agree with most of that.
- Scoundreller 5y ago
  Sounds like the systems would work best where you have both heating and cooling loads throughout the year. Though usually you’re pumping more heat out of the ground than in. There must be a perfect place for these systems where it’s well balanced.
- api 5y ago
  The great thing about geothermal is that it's 24/7 dispatchable without expensive added storage. That would make it a great companion to solar and wind energy in place of natural gas. Even 5-10% of total power on an absolute basis from geothermal could be more valuable than it appears by adding stability to the grid without fossil fuels. Drilling into geothermal would make sense if it were cheaper than adding grid-scale battery storage for nighttime use. The energy flow from the Earth's core is small in a percentage sense, but keep in mind that humanity's energy use is actually tiny when measured on planetary or cosmic scales. Here's the total solar surface area we'd need, for scale: https://www.axionpower.com/knowledge/power-world-with-solar/ https://www.axionpower.com/knowledge/power-world-with-solar/ Cover much of New Mexico with solar PV and you could power all of global industrial civilization (ignoring storage).
- goldenshale 5y ago
  Yeah, per-house is probably never going to make sense, but larger scale operations where they can use hydraulic fracturing techniques to expand the surface area could be the solution. They call these Enhanced Geothermal Systems, and basically they frack the rock between two well bores to try to maximize connectivity and surface area.
  - brtkdotse 5y ago
    I’d say more than half of single family houses in Sweden are heated by geothermal heat pumps, so it’s _very_ viable.
    - phreeza 5y ago
      But not as a source of electricity right?
WarOnPrivacy 5y ago
From the article: Traditional geothermal wells target rare hydrothermal resources Florida geothermal systems pull cool water from the aquifer, use it for A/C and return it via a 2nd well. They're about the only wells that water management districts will rubberstamp. Geothermal cooling (in FL) becomes cost efficient above 15k-20k sq ft (based on my 2010s exp). That led me to an idea that neighborhoods could be cooled by small geothermal utilities. I wonder about increased heat energy down the line but I've seen a doz+ chillers work efficiently, from one 4" well. On a larger scale, downstream heat buildup might be mitigated via a more distributed water system.
- goda90 5y ago
  I'm reminded of this video talking about cooling the London Underground. Since it's running through clay, it's very well insulated and the ground around it is warming year over year. https://www.youtube.com/watch?v=hQo6_GkITe0 https://www.youtube.com/watch?v=hQo6_GkITe0
- Scoundreller 5y ago
  What I always find dumb is when I see a swimming pool and an air conditioner without the two being one system. Do Floridians at least install heat-pump pool heater systems indoors so the cold goes indoors?
  - WarOnPrivacy 5y ago
    I've only seen winter water heating in geothermally cooled homes.
  - beerandt 5y ago
    Swimming pool temperatures in the south easily get over 85, and sometimes 90 degrees in the summer. We always bought big blocks of ice to throw in the pool in the summer to cool it off.
  - cmrdporcupine 5y ago
    I looked into this here, and couldn't find a company to do a heat exchanger hookup for my pool, but also... at least here in the great lakes area, when you want to heat your pool the most is the time when your AC isn't really running (spring / fall), and you don't care about heating your pool as much when the AC is blasting. So while the pool may offer some efficiency gains to the AC, the waste heat from the AC doesn't help much with the pool.
cdeonier 5y ago
Cheap drilling would be a large boon for geothermal, considering the cost of surveying/exploring/drilling is > 50% of the cost of the development of a geothermal site. I don't understand the articles goal of 300C target, though. While some types of geothermal plants do require temperatures that high, binary cycle power plants can use lower temperatures (130C) [1], which seems to open up more area for geothermal development since we expect most gradients between the surface and bottom of the crust to be ~2.5-3.1C / 100M. A lower temperature requirement would in turn allow you to drill less deep, which could consequently also decrease drilling costs. Another thing the article doesn't mention: another interesting approach (aside from improving the technology, like drill bits) is with financing innovation. There have been / are government programs to de-risk the exploration/drilling cost by reimbursing the costs of drilling (80% for failed wells, for example) which also likely adds well data that could better characterize the underlying geothermal resources in regions (which would allow more accurate future development). Really glad to see a deeper dive on geothermal though; its non-intermittency is a valuable characteristic separating it from other renewables that we're currently favoring (solar/wind). Because we generally break down energy generation to LCOE, it omits advantages like uptime of the renewable resource. [1] https://www.energy.gov/eere/geothermal/electricity-generation https://www.energy.gov/eere/geothermal/electricity-generatio...
- deleted 5y ago
  [deleted]
- briffle 5y ago
  My old University powers, heats, and cools itself with Geothermal wells that are at 195F, not sure about the 300C either. (and clears snow/ice from sidewalks and outdoor staaircases) The college also sells extra power to the hospital next door. (it makes around 2MW with a binary cycle plant) https://urbanecologycmu.wordpress.com/2016/11/01/geothermal-energy-oregon-institute-of-technology/ https://urbanecologycmu.wordpress.com/2016/11/01/geothermal-...
- Accujack 5y ago
  I think the 300C target is to support the article's assertion that geothermal could replace e.g. nuclear plants. Geothermal for heating can work well with a lower approach temp, but industrial processes/power generation needs a higher differential.
Factorium 5y ago
Are ground-source heatpumps considered 'geothermal'? Its much less sexy than a giant plant connected to a magma stream, but if we made these routine for all new suburban constructions, alongside passivhaus standards, we could eliminate residential fossil fuel connections for huge sections of the Western world. Like another commenter mentioned, we could even have communal systems for individual streets, drilled beneath roads, to service townhouses and apartment blocks. You can run the ground-source for heating and cooling, alongside a single wall-mounted air conditioner for dehumidification in the summer.
- brtkdotse 5y ago
  Geothermal heat pumps are very common in the Nordics. It’s a one day operation, they come in, drill a 150M hole and run a brine loop hooked up to a heat pump. Sorts the heating and hot water for a 180 m2 house above the attic circle with less than 7000 kWh per year.
  - serpix 5y ago
    that is a ground-source heat pump as the heat energy is mostly from ambient solar. But yes very common and I used to have one in my home before I moved away. It cost practically nothing to keep the house at t-shirt temperature during -25c cold weather snaps.
    - larsalmen 5y ago
      No it's not. The bore-hole is lined with a outer steel pipe until the drill hits bedrock, keeping it very much insulated from the ground. And the upper-most part of the energy-well that's lined is considered inactive, and is not counted in the "150 m deep energy well".
- uuddlrlr 5y ago
  There's a 52-home community in Alberta that provides ~all of their winter heating by storing heat in the ground throughout the summer: https://www.dlsc.ca/borehole.htm https://www.dlsc.ca/borehole.htm It gets up to nearly 80C, but took a few years of operation to get there. The website covers it really well and I'd recommend checking it out.
chris_va 5y ago
Drilling cost is usually estimated as ~depth^2. So, a 1km geothermal well? Break even, and you are limited to only a few places in the world. A 5km geothermal well (needed for broad power availability)? 25x the cost... So, sure, if you can get a 25x cost reduction in an already cutthroat industry, all power to you (no pun intended).
- animal_spirits 5y ago
  It's okay to intend a pun every now and then. Take credit for your poetry ;)
- avernon 5y ago
  Drilling cost is usually estimated for drilling in sedimentary rock with assumptions about how casing is run ;) It is possible that drilling 30,000' of granite has conditions that make the estimation model irrelevant. 5 km isn't really deep enough, anyway. My next post will cover the thermo. It is pretty dang hard to get down to anything approaching $50/MWh. Definitely need more than cheap drilling.
  - DoingIsLearning 5y ago
    It is important that we discuss cost, but I think the urgency of our need for mass generating non-intermitent power should override costs. As an example Solar energy as it exists now would have been ridiculed in the late 80s as something that would never be cost effective. It was the massive subsidies/tax rebate schemes in Germany and later on in other EU countries that open the window for manufacturers to produce at scale and make it the cost competitive source of energy that we see now. I mentioned this in a previous comment on a biomass thread. We would be better off with EU funds allocated to solving the massification of geo-thermal or the massification of small vessel nuclear reactors, than to continue to pour money into converting coal plants into natural gas plants and opening up new biomass furnaces. Natural gas and biomass are just a means for governments to play with statistics on 'renewable' pie-charts. Until we solve the problem of mass energy storage of intermitent renewables or a far away nuclear fussion we need to start _now_ deploying non-carbon emitting non-intermitent energy generation. We have to be realistic and accept that we need to find a means of replacing coal and not all regions have the resources for hydro-generation, geo-thermal is the next best bet considering the time and friction it would take to roll out more nuclear for example.
fouc 5y ago
This seems to be a sequel to https://news.ycombinator.com/item?id=27775927 https://news.ycombinator.com/item?id=27775927 i.e. "Is Geothermal Really Going to be a Thing?" https://austinvernon.site/blog/geothermal.html https://austinvernon.site/blog/geothermal.html
aaron695 5y ago
The USA is the geothermal king, top of the world, so it'd be exciting for them to up their game, no one else is. The depths they are talking about here would be in the top 10 deepest holes and they need to go sideways, unheard of, so it's pushing technology which is also exciting. Geothermal doesn't rely on supply chains for fuel so the military might help with funding. I expect it's not economical, but it's a cool thing to try, bring back 50's science, we need to continue fighting the Woke. This is just a 'study' which generally is code for won't happen, but it would be good if it did, good on Texas - https://www.thinkgeoenergy.com/sage-geosystems-to-explore-geothermal-closed-loop-for-u-s-air-force-base/ https://www.thinkgeoenergy.com/sage-geosystems-to-explore-ge...
shireboy 5y ago
Anecdotally, I looked into this when building our house, and can confirm - the bulk of costs was drilling, and it was expensive. When I did the math at the time, the cost of ground source heat pump over air source heat pump was several times more. Energy bills would be much less, but the payoff was around 20 years, assuming the unit lasted that long.
- kragen 5y ago
  This is totally irrelevant to anything in the article, except in the sense that both pertain to thermal energy and the earth. They have nothing else in common. You can't run a factory, a computer, or a car off a ground-source heat pump, because heat pumps consume energy; they don't produce it.
  - shireboy 5y ago
    Both require drilling that is a major factor in their cost and inhibit adoption was my point. Ground source heat pumps are called “geothermal” systems even though they don’t generate electricity.
    - kragen 5y ago
      You can build ground-source heat pumps by laying pipe in trenches in your yard, which is almost, but not quite, completely unlike drilling through kilometers of rock. It's true that they're sometimes called "geothermal", but they're still totally irrelevant to this article.
julienfr112 5y ago
Could there be a completely novel way of digging ? Maybe with Laser ? maybe a chemical process ? or a high pressure water cutter ? what if you could cut small block of stone in the hole without using so much energy reducing it to sand ?
- mNovak 5y ago
  I imagine part of the challenge would be undercutting the resulting cylindrical rock (still attached to bedrock at the bottom). Also there's the significant issue of removing the cut rock from 10k feet below ground. This is much easier to do with sand which gets picked up in a mud slurry.
- comicjk 5y ago
  They've tried a lot of these things, if not all of them. A colleague of mine in grad school was working on optimally using flame jets to crack the rock ("thermal spallation drilling").
csense 5y ago
I wonder if Elon Musk would be interested in getting into this area. Granted SpaceX is more exciting -- this would be, comparatively, the boring company.
- new_realist 5y ago
  Are there any subsidies or government contracts to be had in geothermal?
stretchwithme 5y ago
I was wondering if extracting geothermal energy could prematurely cool the Earth's core. Here's a few answers: https://earthscience.stackexchange.com/questions/2302/can-the-overuse-of-geothermal-energy-become-an-environmental-concern https://earthscience.stackexchange.com/questions/2302/can-th...
batushka3 5y ago
Technology aside, rollout of such technology in Europe would be sabotated by russkies in the same way shale gas/oil was (sadly successfully). This must be accounted and planned for. Fossil wholesaler of the Siberia does not want you to be gass/oil independant.
deftnerd 5y ago
I live in Ithaca, and Cornell is about to start drilling a test borehole in the coming year. Once the borehole is completed and some tests made, they'll drill a pair of production boreholes about 10,000ft deep. The goal is to pump water down one, and extract it from the other borehole and then use a heat exchanger to pull the anticipated 160F to 180F temperature to provide heat to the entirety of the campus. It's similar to the University's Lake Source Cooling system, which they use the naturally cold water temperature of the local Cayuga lake. At the 250' depth they draw the water in, it's a constant 39F year-round. The cooling system is used to provide chilled water to all the buildings, and a few thousand homes, removing the need for standard air conditioners. The Lake Source Cooling system has saved the university 20 million Kwh a year, an 85% reduction in power usage, since it was made in 2000. It's hoped that the Earth Source Heat project will have the same kind of impact on the energy necessary for heating. There are a lot of unknowns. Nobody has drilled a borehole so deep in this area before because there hasn't been a reason to do it before. [1] https://earthsourceheat.cornell.edu https://earthsourceheat.cornell.edu [2] https://fcs.cornell.edu/departments/energy-sustainability/utilities/cooling-home/cooling-production-home/lake-source-cooling-home/how-lake-source-cooling-works https://fcs.cornell.edu/departments/energy-sustainability/ut... [3] https://fcs.cornell.edu/departments/energy-sustainability/utilities/cooling-home/cooling-production-home/lake-source-cooling https://fcs.cornell.edu/departments/energy-sustainability/ut...

153 points by drocer88 5y ago

I am always a bit bearish on geothermal, because the energy flow through the earths crust is just so damn low. Per surface area, it is about 3 orders of magnitude less than solar irradiation, which means that the circumstances in which it really makes sense to exploit geothermal are those where you can effectively harvest flows from a much larger area, most likely due to convection of water or magma. My understanding is that it will never make sense for e.g. every house in a suburban setting to have their own heat probe and pull energy from that, they will be competing with their neighbors and effective energy gained will be negligible.

streamofdigits 5y ago
is surface area a fair comparison? A deep well should be able to extract all along its length
- cdeonier 5y ago
  How does a deep well extract all along its length? My belief was the production well will experience a gradient (so the bottom of the well will have the temperature you need), and the temperature will drop as you get closer to the surface (which also contributes to the calcite scaling problem geothermal can experience). Also, I think a lot of wells add concrete casing (or metal, as indicated in the article) around portions of the well, which would prevent extraction around those zones of the well.
  - streamofdigits 5y ago
    assuming you can reach a working temperature differential why not continue deeper with the well? From that threshold depth onwards you can extract heat along a line segment that extends to the ultimate depth (which is pressumably dictated by engineering limitations) caveat: thinking like a physicist, not an engineer :-)
Retric 5y ago
It’s often less about the heat flow than simply the amount of heat contained in that volume of rock. For your example: A 1/2 acre home is 2023 m2, 1kg of rock is ~2000j/degrees Celsius, 1 cubic meter of rock is ~2500 kg, down 1k = ~2000 j * 2500 * 2023 * 1000 / 60 / 60 / 1000 ~= 2,800,000 kWh per degC. If you’re talking 1kw of heat on average from that rock you only drop 1 degree after 300 years. Of course 1km is a fairly deep, but if you’re using a heat pump chances are you’re averaging much less than 1kw over the entire year.
- phreeza 5y ago
  Thanks that is a great point I hadn't considered. I suppose strictly speaking it is not renewable when you use it like that, but still pretty clean.
- kragen 5y ago
  This is totally irrelevant to anything in the article, except in the sense that both pertain to thermal energy and the earth. They have nothing else in common. You can't run a factory, a computer, or a car off a ground-source heat pump, because heat pumps consume energy; they don't produce it.
  - Retric 5y ago
    Most of that post had nothing to do with heat pumps, however digging 1km down for a single family home is generally a poor method of extracting energy from the earth as it can be as little as 6C and is only 25C on average above ambient temperature. Much higher ground temperatures are of course useful to create electricity, but such systems are best centralized not used for single family homes. Also, as a centralized system it’s volume is arbitrary. In the north that 6-25C can still make heat pumps vastly more efficient, but you’re extracting energy and cooling that down over time. Which is why it is relevant to the discussion.
    - kragen 5y ago
      I agree with most of that.
Scoundreller 5y ago
Sounds like the systems would work best where you have both heating and cooling loads throughout the year. Though usually you’re pumping more heat out of the ground than in. There must be a perfect place for these systems where it’s well balanced.
api 5y ago
The great thing about geothermal is that it's 24/7 dispatchable without expensive added storage. That would make it a great companion to solar and wind energy in place of natural gas. Even 5-10% of total power on an absolute basis from geothermal could be more valuable than it appears by adding stability to the grid without fossil fuels. Drilling into geothermal would make sense if it were cheaper than adding grid-scale battery storage for nighttime use. The energy flow from the Earth's core is small in a percentage sense, but keep in mind that humanity's energy use is actually tiny when measured on planetary or cosmic scales. Here's the total solar surface area we'd need, for scale: https://www.axionpower.com/knowledge/power-world-with-solar/ https://www.axionpower.com/knowledge/power-world-with-solar/ Cover much of New Mexico with solar PV and you could power all of global industrial civilization (ignoring storage).
goldenshale 5y ago
Yeah, per-house is probably never going to make sense, but larger scale operations where they can use hydraulic fracturing techniques to expand the surface area could be the solution. They call these Enhanced Geothermal Systems, and basically they frack the rock between two well bores to try to maximize connectivity and surface area.
- brtkdotse 5y ago
  I’d say more than half of single family houses in Sweden are heated by geothermal heat pumps, so it’s _very_ viable.
  - phreeza 5y ago
    But not as a source of electricity right?

WarOnPrivacy 5y ago

From the article: Traditional geothermal wells target rare hydrothermal resources Florida geothermal systems pull cool water from the aquifer, use it for A/C and return it via a 2nd well. They're about the only wells that water management districts will rubberstamp. Geothermal cooling (in FL) becomes cost efficient above 15k-20k sq ft (based on my 2010s exp). That led me to an idea that neighborhoods could be cooled by small geothermal utilities. I wonder about increased heat energy down the line but I've seen a doz+ chillers work efficiently, from one 4" well. On a larger scale, downstream heat buildup might be mitigated via a more distributed water system.

goda90 5y ago
I'm reminded of this video talking about cooling the London Underground. Since it's running through clay, it's very well insulated and the ground around it is warming year over year. https://www.youtube.com/watch?v=hQo6_GkITe0 https://www.youtube.com/watch?v=hQo6_GkITe0
Scoundreller 5y ago
What I always find dumb is when I see a swimming pool and an air conditioner without the two being one system. Do Floridians at least install heat-pump pool heater systems indoors so the cold goes indoors?
- WarOnPrivacy 5y ago
  I've only seen winter water heating in geothermally cooled homes.
- beerandt 5y ago
  Swimming pool temperatures in the south easily get over 85, and sometimes 90 degrees in the summer. We always bought big blocks of ice to throw in the pool in the summer to cool it off.
- cmrdporcupine 5y ago
  I looked into this here, and couldn't find a company to do a heat exchanger hookup for my pool, but also... at least here in the great lakes area, when you want to heat your pool the most is the time when your AC isn't really running (spring / fall), and you don't care about heating your pool as much when the AC is blasting. So while the pool may offer some efficiency gains to the AC, the waste heat from the AC doesn't help much with the pool.

cdeonier 5y ago

Cheap drilling would be a large boon for geothermal, considering the cost of surveying/exploring/drilling is > 50% of the cost of the development of a geothermal site. I don't understand the articles goal of 300C target, though. While some types of geothermal plants do require temperatures that high, binary cycle power plants can use lower temperatures (130C) [1], which seems to open up more area for geothermal development since we expect most gradients between the surface and bottom of the crust to be ~2.5-3.1C / 100M. A lower temperature requirement would in turn allow you to drill less deep, which could consequently also decrease drilling costs. Another thing the article doesn't mention: another interesting approach (aside from improving the technology, like drill bits) is with financing innovation. There have been / are government programs to de-risk the exploration/drilling cost by reimbursing the costs of drilling (80% for failed wells, for example) which also likely adds well data that could better characterize the underlying geothermal resources in regions (which would allow more accurate future development). Really glad to see a deeper dive on geothermal though; its non-intermittency is a valuable characteristic separating it from other renewables that we're currently favoring (solar/wind). Because we generally break down energy generation to LCOE, it omits advantages like uptime of the renewable resource. [1] https://www.energy.gov/eere/geothermal/electricity-generation https://www.energy.gov/eere/geothermal/electricity-generatio...

deleted 5y ago
[deleted]
briffle 5y ago
My old University powers, heats, and cools itself with Geothermal wells that are at 195F, not sure about the 300C either. (and clears snow/ice from sidewalks and outdoor staaircases) The college also sells extra power to the hospital next door. (it makes around 2MW with a binary cycle plant) https://urbanecologycmu.wordpress.com/2016/11/01/geothermal-energy-oregon-institute-of-technology/ https://urbanecologycmu.wordpress.com/2016/11/01/geothermal-...
Accujack 5y ago
I think the 300C target is to support the article's assertion that geothermal could replace e.g. nuclear plants. Geothermal for heating can work well with a lower approach temp, but industrial processes/power generation needs a higher differential.

Factorium 5y ago

Are ground-source heatpumps considered 'geothermal'? Its much less sexy than a giant plant connected to a magma stream, but if we made these routine for all new suburban constructions, alongside passivhaus standards, we could eliminate residential fossil fuel connections for huge sections of the Western world. Like another commenter mentioned, we could even have communal systems for individual streets, drilled beneath roads, to service townhouses and apartment blocks. You can run the ground-source for heating and cooling, alongside a single wall-mounted air conditioner for dehumidification in the summer.

brtkdotse 5y ago
Geothermal heat pumps are very common in the Nordics. It’s a one day operation, they come in, drill a 150M hole and run a brine loop hooked up to a heat pump. Sorts the heating and hot water for a 180 m2 house above the attic circle with less than 7000 kWh per year.
- serpix 5y ago
  that is a ground-source heat pump as the heat energy is mostly from ambient solar. But yes very common and I used to have one in my home before I moved away. It cost practically nothing to keep the house at t-shirt temperature during -25c cold weather snaps.
  - larsalmen 5y ago
    No it's not. The bore-hole is lined with a outer steel pipe until the drill hits bedrock, keeping it very much insulated from the ground. And the upper-most part of the energy-well that's lined is considered inactive, and is not counted in the "150 m deep energy well".
uuddlrlr 5y ago
There's a 52-home community in Alberta that provides ~all of their winter heating by storing heat in the ground throughout the summer: https://www.dlsc.ca/borehole.htm https://www.dlsc.ca/borehole.htm It gets up to nearly 80C, but took a few years of operation to get there. The website covers it really well and I'd recommend checking it out.

chris_va 5y ago

Drilling cost is usually estimated as ~depth^2. So, a 1km geothermal well? Break even, and you are limited to only a few places in the world. A 5km geothermal well (needed for broad power availability)? 25x the cost... So, sure, if you can get a 25x cost reduction in an already cutthroat industry, all power to you (no pun intended).

animal_spirits 5y ago
It's okay to intend a pun every now and then. Take credit for your poetry ;)
avernon 5y ago
Drilling cost is usually estimated for drilling in sedimentary rock with assumptions about how casing is run ;) It is possible that drilling 30,000' of granite has conditions that make the estimation model irrelevant. 5 km isn't really deep enough, anyway. My next post will cover the thermo. It is pretty dang hard to get down to anything approaching $50/MWh. Definitely need more than cheap drilling.
- DoingIsLearning 5y ago
  It is important that we discuss cost, but I think the urgency of our need for mass generating non-intermitent power should override costs. As an example Solar energy as it exists now would have been ridiculed in the late 80s as something that would never be cost effective. It was the massive subsidies/tax rebate schemes in Germany and later on in other EU countries that open the window for manufacturers to produce at scale and make it the cost competitive source of energy that we see now. I mentioned this in a previous comment on a biomass thread. We would be better off with EU funds allocated to solving the massification of geo-thermal or the massification of small vessel nuclear reactors, than to continue to pour money into converting coal plants into natural gas plants and opening up new biomass furnaces. Natural gas and biomass are just a means for governments to play with statistics on 'renewable' pie-charts. Until we solve the problem of mass energy storage of intermitent renewables or a far away nuclear fussion we need to start _now_ deploying non-carbon emitting non-intermitent energy generation. We have to be realistic and accept that we need to find a means of replacing coal and not all regions have the resources for hydro-generation, geo-thermal is the next best bet considering the time and friction it would take to roll out more nuclear for example.

fouc 5y ago

This seems to be a sequel to https://news.ycombinator.com/item?id=27775927 https://news.ycombinator.com/item?id=27775927 i.e. "Is Geothermal Really Going to be a Thing?" https://austinvernon.site/blog/geothermal.html https://austinvernon.site/blog/geothermal.html

aaron695 5y ago

The USA is the geothermal king, top of the world, so it'd be exciting for them to up their game, no one else is. The depths they are talking about here would be in the top 10 deepest holes and they need to go sideways, unheard of, so it's pushing technology which is also exciting. Geothermal doesn't rely on supply chains for fuel so the military might help with funding. I expect it's not economical, but it's a cool thing to try, bring back 50's science, we need to continue fighting the Woke. This is just a 'study' which generally is code for won't happen, but it would be good if it did, good on Texas - https://www.thinkgeoenergy.com/sage-geosystems-to-explore-geothermal-closed-loop-for-u-s-air-force-base/ https://www.thinkgeoenergy.com/sage-geosystems-to-explore-ge...

shireboy 5y ago

Anecdotally, I looked into this when building our house, and can confirm - the bulk of costs was drilling, and it was expensive. When I did the math at the time, the cost of ground source heat pump over air source heat pump was several times more. Energy bills would be much less, but the payoff was around 20 years, assuming the unit lasted that long.

kragen 5y ago
This is totally irrelevant to anything in the article, except in the sense that both pertain to thermal energy and the earth. They have nothing else in common. You can't run a factory, a computer, or a car off a ground-source heat pump, because heat pumps consume energy; they don't produce it.
- shireboy 5y ago
  Both require drilling that is a major factor in their cost and inhibit adoption was my point. Ground source heat pumps are called “geothermal” systems even though they don’t generate electricity.
  - kragen 5y ago
    You can build ground-source heat pumps by laying pipe in trenches in your yard, which is almost, but not quite, completely unlike drilling through kilometers of rock. It's true that they're sometimes called "geothermal", but they're still totally irrelevant to this article.

julienfr112 5y ago

Could there be a completely novel way of digging ? Maybe with Laser ? maybe a chemical process ? or a high pressure water cutter ? what if you could cut small block of stone in the hole without using so much energy reducing it to sand ?

mNovak 5y ago
I imagine part of the challenge would be undercutting the resulting cylindrical rock (still attached to bedrock at the bottom). Also there's the significant issue of removing the cut rock from 10k feet below ground. This is much easier to do with sand which gets picked up in a mud slurry.
comicjk 5y ago
They've tried a lot of these things, if not all of them. A colleague of mine in grad school was working on optimally using flame jets to crack the rock ("thermal spallation drilling").

csense 5y ago

I wonder if Elon Musk would be interested in getting into this area. Granted SpaceX is more exciting -- this would be, comparatively, the boring company.

new_realist 5y ago
Are there any subsidies or government contracts to be had in geothermal?

stretchwithme 5y ago

I was wondering if extracting geothermal energy could prematurely cool the Earth's core. Here's a few answers: https://earthscience.stackexchange.com/questions/2302/can-the-overuse-of-geothermal-energy-become-an-environmental-concern https://earthscience.stackexchange.com/questions/2302/can-th...

batushka3 5y ago

Technology aside, rollout of such technology in Europe would be sabotated by russkies in the same way shale gas/oil was (sadly successfully). This must be accounted and planned for. Fossil wholesaler of the Siberia does not want you to be gass/oil independant.

deftnerd 5y ago

I live in Ithaca, and Cornell is about to start drilling a test borehole in the coming year. Once the borehole is completed and some tests made, they'll drill a pair of production boreholes about 10,000ft deep. The goal is to pump water down one, and extract it from the other borehole and then use a heat exchanger to pull the anticipated 160F to 180F temperature to provide heat to the entirety of the campus. It's similar to the University's Lake Source Cooling system, which they use the naturally cold water temperature of the local Cayuga lake. At the 250' depth they draw the water in, it's a constant 39F year-round. The cooling system is used to provide chilled water to all the buildings, and a few thousand homes, removing the need for standard air conditioners. The Lake Source Cooling system has saved the university 20 million Kwh a year, an 85% reduction in power usage, since it was made in 2000. It's hoped that the Earth Source Heat project will have the same kind of impact on the energy necessary for heating. There are a lot of unknowns. Nobody has drilled a borehole so deep in this area before because there hasn't been a reason to do it before. [1] https://earthsourceheat.cornell.edu https://earthsourceheat.cornell.edu [2] https://fcs.cornell.edu/departments/energy-sustainability/utilities/cooling-home/cooling-production-home/lake-source-cooling-home/how-lake-source-cooling-works https://fcs.cornell.edu/departments/energy-sustainability/ut... [3] https://fcs.cornell.edu/departments/energy-sustainability/utilities/cooling-home/cooling-production-home/lake-source-cooling https://fcs.cornell.edu/departments/energy-sustainability/ut...