13 ms·

Why geothermal isn't ubiquitous and how it might get that way

167 points by Osiris30 5y ago

Animats 5y ago
Most current efforts need a lot to go right just to reach mediocrity. Right. It may be do-able, but unlikely to be cost effective in deep hard rock. One of the deepest drilling projects got down 31,400 feet, but instead of hitting something saleable like natural gas or oil, they got liquid sulfur.
- eloff 5y ago
  I think you're referring to the hole drilled in Oklahoma back in the seventies: https://en.wikipedia.org/wiki/Bertha_Rogers https://en.wikipedia.org/wiki/Bertha_Rogers
curtis3389 5y ago
Hug of death? https://web.archive.org/web/20210707172539/https://austinvernon.eth.link/blog/geothermal.html https://web.archive.org/web/20210707172539/https://austinver...
blakesterz 5y ago
This seems to be all about Geothermal HEATING, which seems pretty tough in most places. I thought Geothermal Cooling is easier/cheaper in many areas? Heat from Geothermal seems really difficult because you have to drill so deep almost everywhere, but that's not the case for cooling, is it? Iceland seems to have some decent heat there: https://en.wikipedia.org/wiki/Geothermal_power_in_Iceland https://en.wikipedia.org/wiki/Geothermal_power_in_Iceland Five major geothermal power plants exist in Iceland, which produce approximately 26.2% (2010) of the nation's electricity.
- abrowne 5y ago
  Keep in mind Iceland's population is under 400k. That's less than the city proper of Minneapolis, for example.
  - oscardssmith 5y ago
    That said, Iceland does in effect export a ton of power by importing bauxite and turning it into aluminum.
    - y04nn 5y ago
      Indeed, in 2011, 71% [1] of the electricity production of Iceland was used by the aluminum industry! [1] https://en.wikipedia.org/wiki/Electricity_sector_in_Iceland#Consumption https://en.wikipedia.org/wiki/Electricity_sector_in_Iceland#...
    - abrowne 5y ago
      True, although I think that's hydropower? At least that's what I remember from when I studied there ~15 years ago.
- wffurr 5y ago
  To heat a home with geothermal, you use a heat pump. It works better than an air source heat pump most places because the ground doesn't get as cold as the air does. More widely deploying ground source heat pumps for home heating seems more promising than pursuing geothermal electricity generation. The problem with ground source heat pumps is that the lifecycle of the equivalent if 30-50 years, well outside the typical homeowner's planning or payback horizon.
  - coryrc 5y ago
    For the same cost we could install multiple air-source heat pumps at nearly the same efficiency. That's a way better tradeoff.
  - Johnny555 5y ago
    I wish ground source heat pumps were more affordable, I asked my HVAC installer, he said I was looking at $30K+ including returning the yard to the state it was in before they trenched in the pipes. That's 3X the cost of the air source heat pump I ended up going with.
    - friendzis 5y ago
      > I wish ground source heat pumps were more affordable I don't think this will ever be the case. Water-to-water (ground source) and air-to-water (air source) heat pumps are effectively the same thing technically sans some tuning for temperatures, therefore the difference in cost of the heat pump itself is never going to be high. The cost difference is in installation costs. Air-to-water heat pump installation is as simple as mounting the external unit and routing a few pipes back to interior unit while water-to-water installation is routing the distributed heat exchanger, which is significantly more labor intensive even if you do not account for landscaping (e.g. done as part of greenfield development which will have landscaping done anyway).
  - smichel17 5y ago
    The house I grew up in had a geothermal system (installed when my parents built the house). I was a bit young to know the precise details, but I believe the idea was that the ground loop merely heated or cooled (depending on the season) to the ground's ambient temperature, around 60ºF. From there, it was further heated using traditional methods. I think that meant a heat pump, as you mention, but it might have been oil. The energy savings in the winter (US-MA) was nice -- heating from 60 is a lot less energy than heating from 30 or below -- but the summer was the real reason I'll absolutely install geothermal in any house I build: basically free a/c. Not having to think about setting the thermostat for a relatively large house down to 72 (or even lower, if you want to freeze your tookus off) is so freeing.
- a1371 5y ago
  Same heat transfer dynamics apply to cooling as well. Earth is a really good insulator, that's why it has a steady temperature in the first place. If you dump too much heat in it, it will warm up. That's seen as an advantage when you can harvest the same heat in the colder months using geothermal heat pumps. Some buildings that have access to the ocean or a lake can use that for heat rejection because those take the heat away. None of these applications require going too deep in the ground. This article is all about going deep. Iceland has access to very hot water in shallow ground. They are unique that way.
- comicjk 5y ago
  Ground-source heating/cooling is quite different from geothermal heat or power. With ground-source, you just have a heat pump like an ordinary air conditioner, but using the ground as the heat sink instead of outside air. A couple of meters is deep enough. It's nothing like prospecting for the rare resource of accessible hot rock or natural steam, as in Iceland.
- maxerickson 5y ago
  The systems used for cooling work just as well for heating. Really heating is probably the reason most of them are installed, and then, hey, why not also use it during the summer.
- deleted 5y ago
  [deleted]
- kragen 5y ago
  Your comment is entirely unrelated to the article, which is about using the very hot rock several kilometers underground to drive turbines to generate electricity.
fatsdomino001 5y ago
What I find most fascinating is that this is an .eth link. Starting to see them everywhere. Does anyone know why there’s a “.link” after “.eth”?
- hanniabu 5y ago
  It's a decentralized site using ENS so you'd need to run an ETH node and IPFS to view it. Cloudflare was generous enough to do the hard part and host those and serve the sites though the .link TLD to support casual browsing.
  - mcguire 5y ago
    See also https://eth.link/ https://eth.link/.
- erulabs 5y ago
  A legitimately useful blockchain application - who knew!?
  - verdverm 5y ago
    Except that the sites are actually hosted on a centralized service and mirrors the "decentralized" content? People prefer centralized services ~ who knew???
    - Black101 5y ago
      > People prefer centralized services ~ who knew??? that's not why... it's because they don't know how to access the real source.
      - Qwertious 5y ago
        And why does the real source remain obscure? You can blame the chicken/egg problem, but ultimately the reason why decentralized systems don't overtake centralized systems is that they don't offer much of an advantage over them, so nobody cares enough to learn how to access them. I mean, suppose Cloudflare/whatever goes down and the site is inaccessible: would you: A) Grab the link, and go figure out how to pull it out of IPFS directly B) Grab the link, and paste it into archive.org or C) Go grab a coffee, then come back and refresh the page (because when Cloudflare does go down, it tends to be only down shortly) B and C aren't perfect, but they're close enough. Doing A takes effort and frankly isn't worth it unless you're doing it as a hobby.
kristopolous 5y ago
Ucs, the controversial organization, has an interesting analysis of geothermal. https://www.ucsusa.org/resources/environmental-impacts-geothermal-energy https://www.ucsusa.org/resources/environmental-impacts-geoth... The takeaway > Enhanced geothermal systems, which require energy to drill and pump water into hot rock reservoirs, have life-cycle global warming emission of approximately 0.2 pounds of carbon dioxide equivalent per kilowatt-hour [11]. > To put this into context, estimates of life-cycle global warming emissions for natural gas generated electricity are between 0.6 and 2 pounds of carbon dioxide equivalent per kilowatt-hour and estimates for coal-generated electricity are 1.4 and 3.6 pounds of carbon dioxide equivalent per kilowatt-hour. Nothing is really truly zero carbon currently. Solar has manufacturing and maintenance. Nuclear has construction, mining, refinement, containment, etc. It's nice to see the full lifecycle being looked at. We can't pretend that something essential for the process doesn't matter because we do a classification handwaving. It all counts
- goda90 5y ago
  So we should be doing calculations of "what percentage of its lifetime power production is required to sequester the carbon it took to create and use it?"
  - kristopolous 5y ago
    That's almost a peak oil approach, which was both insufficient and the most accurate possible. We can only state things in terms of stuff which currently exists. The future will yield different results because new techniques and technologies will come along. But we can't rely on or predict them. There's a lot of "pons and fleischmanning" when talking about future energy use - mass scale geo-engineering or sucking carbon out of the atmosphere technology, it has to be avoided. The technologies don't exist yet. We have to use real-world stuff. Using current reality for future projections is inherently defective because of the innovation factor and routinely leads to bad predictions (such as peak oil[1]), but it's the only reality we have and is sadly as good as we're going to get. Anything else (such as say next-gen nuclear) has to be regarded as a fiction in the calculations until it actually exists. It's messy, sloppy, and requires a large trashcan but the alternative is to get to results that rely on things that literally do not actually exist. Kinda like how the people planning Operation Downfall (the land invasion of japan during ww2) weren't told about all the other things in the works (backroom deal to get Russia to declare war on Japan and the Manhattan project), they had to assume those things would continue to not happen. [1] - The Hubbert peak was essentially that the amount of energy to extract and refine oil would surpass the energy from the oil and thus make it unsustainable so the operations for oil extraction would cease. New techniques have been developed (such as fracking) which have changed this math, but in 1956, using 1956 knowledge, this was the best prediction possible. It's somewhat Malthusian - who was also as "correct as possible" with the best science that 1798 had to offer. He couldn't factor in, say, the Haber–Bosch process from 112 years in the future in his food growth computations.
SEJeff 5y ago
I just priced out HVAC for a large home in central KY. It worked out to 3 of the highest efficiency American Standard/Trane units (Central Heating and Air) for around 50k or a touch over 70k for Bosch Geothermal. The big caveat for geothermal was the 70k price was guaranteed only if they didn't hit rock when digging. They couldn't give me a guaranteed price if they did hit rock so the choice was obvious. I picked Central Heating and Air. For horizontal or vertical geothermal loops, the biggest cost is always going to be digging for the loops. Until they make that more affordable, they're going to have a hard time making it more ubiquitous.
- taneq 5y ago
  What counts as a "large home" here? 50k USD for aircon seems insane!
  - SEJeff 5y ago
    ~6,500sqft / 4 stories with a basement. The price a year ago would have been more like 20k, but with the crazy price of lumber and all building materials going up, the HVAC companies followed suit :(
    - codingdave 5y ago
      Please tell me this is a full build-out of not only the HVAC system, but all ductwork and construction as well? Otherwise, you are getting royally ripped off.
      - SEJeff 5y ago
        Full buildout, cutting holes and running ductwork, etc. Thats the quote for materials and labor, yes. If I did it a year ago it would be 20k less :/
        Cipater 5y ago
        Would you mind detailing why the cost difference would be so large from last year to this? An almost 100% increase is quite substantial, no?
russellbeattie 5y ago
I've wondered if there could be a way to use the Earth's heat by drilling a small hole in your back yard a few km deep and somehow embedding a tiny generator down there to take advantage of the heat differential between various layers of rock. Maybe a Stirling engine? I'm thinking like a long thin tube filled with liquid that boils at low temps. The liquid would boil, expand, rise up through an insulated tube, condense at a cooler layer and circulate back down. A little generator could use the constant motion to power a house.
- comicjk 5y ago
  Deep holes are expensive. Oil drilling, the cheapest kind of drilling since it's very common and in soft rock, costs $100-$200 per vertical foot.* A 2 km hole would cost $650,000 - $1.3M. It would not be economical to do this for one house. Then there are operating costs: operating a power plant on the surface is very likely to be cheaper than operating one underground, and temperature difference is bigger. All in all, a traditional geothermal plant (utility scale, at the surface) looks like that for good reasons. *https://www.oilgasequity.com/resources/drilling-completion-facts/ https://www.oilgasequity.com/resources/drilling-completion-f...
- tootie 5y ago
  Residential geothermal heat pumps are commercially available. Generating electricity is possible but less practical. Using it to heat and cool your home without fuel is very doable. https://www.energy.gov/energysaver/choosing-and-installing-geothermal-heat-pumps https://www.energy.gov/energysaver/choosing-and-installing-g...
turtlebits 5y ago
IMO, geothermal doesn't really make sense. It's expensive, and the heat gradient isn't huge- you have to drill or dig huge trenches to make up for it. Solar water heating is extremely efficient (and less complicated), but I have never seen it in the US. As for cooling, if it's hot out, the sun is probably out- solar PV with AC/heat pump should be fine.
- olivierlacan 5y ago
  I've seen solar water heaters routinely on roofs in Florida and other U.S. states that get sufficient heat (Arizona, etc.). I'm not sure either of our observations are useful to determine how prevalent rooftop solar water heating is.
  - lostapathy 5y ago
    Solar water heaters have really fallen out of favor because to make them robust, they are more complicated than you'd think. It's generally not viable to just run a water pipe onto the roof, due to both freezing and temperature regulation concerns. So you end up with a closed loop system (filled with a glycol solution that won't freeze) and a heat exchanger to get the water into your domestic supply and at a consistent temperature. Not to mention the service issues of having something "weird" on your house as a critical system. Nowadays, we have electric heat pump water heaters that are very efficient, so running that in conjunction with solar panels to generate electricity can make a lot more sense in practice.
    - msandford 5y ago
      I wish it was easy to buy a gas hot water heater that also had a few coils of copper in it so I could plumb in whatever kind of energy harvesting heat source I could come up with. It'd be great to tap into the heat my AC throws off, or a closed loop solar thermal panel, or both!
      - lostapathy 5y ago
        It really is a shame that HVAC contractors want to mark up more efficient or "exotic" options so much higher than the "base" option. I had my AC replaced a few years back for like $3500, with "least efficient we can legally sell". Doing anything else was going to double the price, even though the wholesale cost difference to the next step up was under 20% of that.
berlincount 5y ago
The first geothermal wells in Germany have exhausted their heat gradient; after less than 30 years … so, unless you’re actually in Iceland or the Canaries or something similar, this might not even sustainable for even one full generation …
- dexwiz 5y ago
  Will they “recharge?” If so, on what time scale?
  - Faaak 5y ago
    They can either recharge naturally (i.e. with earth conduction), but it takes a lot of time. Or you can also recharge them during the summer, either with solar thermal panels, or on a small measure, by running your HVAC "backwards" (i.e. cooling your home and thus heating the wells)
    - restalis 5y ago
      The wells would recharge even without Earth's existing surrounding heat reserves. Moon (and Sun) induced tidal forces do manifest not only in the body of water but also in the Earth's crust, and the resulting tension/friction is quite a source of energy/heat.
- Chris2048 5y ago
  funny question: can they dig deeper basements now?
- xscott 5y ago
  Conservatively, there's enough heat down there for the current world's energy use for 17 billion years: https://www.wired.com/story/how-long-will-earths-geothermal-energy-last/ https://www.wired.com/story/how-long-will-earths-geothermal-... Considering our sun will explode in 5.5 billion years, that should be good enough.
  - 5y ago
tpmx 5y ago
For nordic climates: After running the numbers I was surprised by how little benefit I'd get from geothermal drilling + heat pump for a much larger investment (like $30k including internal fitting of water-based radiators) compared to a regular outdoor air/air heat pump for $2k. Ongoing costs would be like 5-8% lower. Modern air/air heat pumps are awesome.
- Retric 5y ago
  Local conditions can dramatically change these numbers. In places where the ground temperature is 20C you use dramatically less energy to heat and cool with a ground source heat pump. Nordic countries have minimal need for cooling and high levels of insulation minimize the need for heating. The worst for heat pumps is simply resistance heating which isn’t that much worse than the a heat pump connected to 5C or less ground temperatures. On top of this 30k is on the high end for ground source heat pumps.
  - tpmx 5y ago
    > Nordic countries have minimal need for cooling and high levels of insulation minimize the need for heating. I bought this lovely house built in the 1910s... > On top of this 30k is on the high end for ground source heat pumps. Do note that this estimate included the cost for equipping the house with water-based radioators.
    - Retric 5y ago
      Yea, the water based radiators is a different system than the common approach of having a closed ground loop connected to a heat pump. https://en.wikipedia.org/wiki/Ground_source_heat_pump https://en.wikipedia.org/wiki/Ground_source_heat_pump
  - briHass 5y ago
    Define 'much worse'. Even basic heat pumps in traditional air/air split systems can achieve COPs of 3-4 above freezing air temps. The modern mini splits can do that well below freezing. Nowhere has electric so cheap that a 2x or 3x reduction in the amount of electricity used to heat wouldn't result in massive savings.
cmiller1 5y ago
> Is This Industry Trying to Punch Holes in the Ground or Virtue Signal? What?

167 points by Osiris30 5y ago

Most current efforts need a lot to go right just to reach mediocrity. Right. It may be do-able, but unlikely to be cost effective in deep hard rock. One of the deepest drilling projects got down 31,400 feet, but instead of hitting something saleable like natural gas or oil, they got liquid sulfur.

eloff 5y ago
I think you're referring to the hole drilled in Oklahoma back in the seventies: https://en.wikipedia.org/wiki/Bertha_Rogers https://en.wikipedia.org/wiki/Bertha_Rogers

curtis3389 5y ago

Hug of death? https://web.archive.org/web/20210707172539/https://austinvernon.eth.link/blog/geothermal.html https://web.archive.org/web/20210707172539/https://austinver...

blakesterz 5y ago

This seems to be all about Geothermal HEATING, which seems pretty tough in most places. I thought Geothermal Cooling is easier/cheaper in many areas? Heat from Geothermal seems really difficult because you have to drill so deep almost everywhere, but that's not the case for cooling, is it? Iceland seems to have some decent heat there: https://en.wikipedia.org/wiki/Geothermal_power_in_Iceland https://en.wikipedia.org/wiki/Geothermal_power_in_Iceland Five major geothermal power plants exist in Iceland, which produce approximately 26.2% (2010) of the nation's electricity.

abrowne 5y ago
Keep in mind Iceland's population is under 400k. That's less than the city proper of Minneapolis, for example.
- oscardssmith 5y ago
  That said, Iceland does in effect export a ton of power by importing bauxite and turning it into aluminum.
  - y04nn 5y ago
    Indeed, in 2011, 71% [1] of the electricity production of Iceland was used by the aluminum industry! [1] https://en.wikipedia.org/wiki/Electricity_sector_in_Iceland#Consumption https://en.wikipedia.org/wiki/Electricity_sector_in_Iceland#...
  - abrowne 5y ago
    True, although I think that's hydropower? At least that's what I remember from when I studied there ~15 years ago.
wffurr 5y ago
To heat a home with geothermal, you use a heat pump. It works better than an air source heat pump most places because the ground doesn't get as cold as the air does. More widely deploying ground source heat pumps for home heating seems more promising than pursuing geothermal electricity generation. The problem with ground source heat pumps is that the lifecycle of the equivalent if 30-50 years, well outside the typical homeowner's planning or payback horizon.
- coryrc 5y ago
  For the same cost we could install multiple air-source heat pumps at nearly the same efficiency. That's a way better tradeoff.
- Johnny555 5y ago
  I wish ground source heat pumps were more affordable, I asked my HVAC installer, he said I was looking at $30K+ including returning the yard to the state it was in before they trenched in the pipes. That's 3X the cost of the air source heat pump I ended up going with.
  - friendzis 5y ago
    > I wish ground source heat pumps were more affordable I don't think this will ever be the case. Water-to-water (ground source) and air-to-water (air source) heat pumps are effectively the same thing technically sans some tuning for temperatures, therefore the difference in cost of the heat pump itself is never going to be high. The cost difference is in installation costs. Air-to-water heat pump installation is as simple as mounting the external unit and routing a few pipes back to interior unit while water-to-water installation is routing the distributed heat exchanger, which is significantly more labor intensive even if you do not account for landscaping (e.g. done as part of greenfield development which will have landscaping done anyway).
- smichel17 5y ago
  The house I grew up in had a geothermal system (installed when my parents built the house). I was a bit young to know the precise details, but I believe the idea was that the ground loop merely heated or cooled (depending on the season) to the ground's ambient temperature, around 60ºF. From there, it was further heated using traditional methods. I think that meant a heat pump, as you mention, but it might have been oil. The energy savings in the winter (US-MA) was nice -- heating from 60 is a lot less energy than heating from 30 or below -- but the summer was the real reason I'll absolutely install geothermal in any house I build: basically free a/c. Not having to think about setting the thermostat for a relatively large house down to 72 (or even lower, if you want to freeze your tookus off) is so freeing.
a1371 5y ago
Same heat transfer dynamics apply to cooling as well. Earth is a really good insulator, that's why it has a steady temperature in the first place. If you dump too much heat in it, it will warm up. That's seen as an advantage when you can harvest the same heat in the colder months using geothermal heat pumps. Some buildings that have access to the ocean or a lake can use that for heat rejection because those take the heat away. None of these applications require going too deep in the ground. This article is all about going deep. Iceland has access to very hot water in shallow ground. They are unique that way.
comicjk 5y ago
Ground-source heating/cooling is quite different from geothermal heat or power. With ground-source, you just have a heat pump like an ordinary air conditioner, but using the ground as the heat sink instead of outside air. A couple of meters is deep enough. It's nothing like prospecting for the rare resource of accessible hot rock or natural steam, as in Iceland.
maxerickson 5y ago
The systems used for cooling work just as well for heating. Really heating is probably the reason most of them are installed, and then, hey, why not also use it during the summer.
deleted 5y ago
[deleted]
kragen 5y ago
Your comment is entirely unrelated to the article, which is about using the very hot rock several kilometers underground to drive turbines to generate electricity.

fatsdomino001 5y ago

What I find most fascinating is that this is an .eth link. Starting to see them everywhere. Does anyone know why there’s a “.link” after “.eth”?

hanniabu 5y ago
It's a decentralized site using ENS so you'd need to run an ETH node and IPFS to view it. Cloudflare was generous enough to do the hard part and host those and serve the sites though the .link TLD to support casual browsing.
- mcguire 5y ago
  See also https://eth.link/ https://eth.link/.
erulabs 5y ago
A legitimately useful blockchain application - who knew!?
- verdverm 5y ago
  Except that the sites are actually hosted on a centralized service and mirrors the "decentralized" content? People prefer centralized services ~ who knew???
  - Black101 5y ago
    > People prefer centralized services ~ who knew??? that's not why... it's because they don't know how to access the real source.
    - Qwertious 5y ago
      And why does the real source remain obscure? You can blame the chicken/egg problem, but ultimately the reason why decentralized systems don't overtake centralized systems is that they don't offer much of an advantage over them, so nobody cares enough to learn how to access them. I mean, suppose Cloudflare/whatever goes down and the site is inaccessible: would you: A) Grab the link, and go figure out how to pull it out of IPFS directly B) Grab the link, and paste it into archive.org or C) Go grab a coffee, then come back and refresh the page (because when Cloudflare does go down, it tends to be only down shortly) B and C aren't perfect, but they're close enough. Doing A takes effort and frankly isn't worth it unless you're doing it as a hobby.

kristopolous 5y ago

Ucs, the controversial organization, has an interesting analysis of geothermal. https://www.ucsusa.org/resources/environmental-impacts-geothermal-energy https://www.ucsusa.org/resources/environmental-impacts-geoth... The takeaway > Enhanced geothermal systems, which require energy to drill and pump water into hot rock reservoirs, have life-cycle global warming emission of approximately 0.2 pounds of carbon dioxide equivalent per kilowatt-hour [11]. > To put this into context, estimates of life-cycle global warming emissions for natural gas generated electricity are between 0.6 and 2 pounds of carbon dioxide equivalent per kilowatt-hour and estimates for coal-generated electricity are 1.4 and 3.6 pounds of carbon dioxide equivalent per kilowatt-hour. Nothing is really truly zero carbon currently. Solar has manufacturing and maintenance. Nuclear has construction, mining, refinement, containment, etc. It's nice to see the full lifecycle being looked at. We can't pretend that something essential for the process doesn't matter because we do a classification handwaving. It all counts

goda90 5y ago
So we should be doing calculations of "what percentage of its lifetime power production is required to sequester the carbon it took to create and use it?"
- kristopolous 5y ago
  That's almost a peak oil approach, which was both insufficient and the most accurate possible. We can only state things in terms of stuff which currently exists. The future will yield different results because new techniques and technologies will come along. But we can't rely on or predict them. There's a lot of "pons and fleischmanning" when talking about future energy use - mass scale geo-engineering or sucking carbon out of the atmosphere technology, it has to be avoided. The technologies don't exist yet. We have to use real-world stuff. Using current reality for future projections is inherently defective because of the innovation factor and routinely leads to bad predictions (such as peak oil[1]), but it's the only reality we have and is sadly as good as we're going to get. Anything else (such as say next-gen nuclear) has to be regarded as a fiction in the calculations until it actually exists. It's messy, sloppy, and requires a large trashcan but the alternative is to get to results that rely on things that literally do not actually exist. Kinda like how the people planning Operation Downfall (the land invasion of japan during ww2) weren't told about all the other things in the works (backroom deal to get Russia to declare war on Japan and the Manhattan project), they had to assume those things would continue to not happen. [1] - The Hubbert peak was essentially that the amount of energy to extract and refine oil would surpass the energy from the oil and thus make it unsustainable so the operations for oil extraction would cease. New techniques have been developed (such as fracking) which have changed this math, but in 1956, using 1956 knowledge, this was the best prediction possible. It's somewhat Malthusian - who was also as "correct as possible" with the best science that 1798 had to offer. He couldn't factor in, say, the Haber–Bosch process from 112 years in the future in his food growth computations.

SEJeff 5y ago

I just priced out HVAC for a large home in central KY. It worked out to 3 of the highest efficiency American Standard/Trane units (Central Heating and Air) for around 50k or a touch over 70k for Bosch Geothermal. The big caveat for geothermal was the 70k price was guaranteed only if they didn't hit rock when digging. They couldn't give me a guaranteed price if they did hit rock so the choice was obvious. I picked Central Heating and Air. For horizontal or vertical geothermal loops, the biggest cost is always going to be digging for the loops. Until they make that more affordable, they're going to have a hard time making it more ubiquitous.

taneq 5y ago
What counts as a "large home" here? 50k USD for aircon seems insane!
- SEJeff 5y ago
  ~6,500sqft / 4 stories with a basement. The price a year ago would have been more like 20k, but with the crazy price of lumber and all building materials going up, the HVAC companies followed suit :(
  - codingdave 5y ago
    Please tell me this is a full build-out of not only the HVAC system, but all ductwork and construction as well? Otherwise, you are getting royally ripped off.
    - SEJeff 5y ago
      Full buildout, cutting holes and running ductwork, etc. Thats the quote for materials and labor, yes. If I did it a year ago it would be 20k less :/
      - Cipater 5y ago
        Would you mind detailing why the cost difference would be so large from last year to this? An almost 100% increase is quite substantial, no?

russellbeattie 5y ago

I've wondered if there could be a way to use the Earth's heat by drilling a small hole in your back yard a few km deep and somehow embedding a tiny generator down there to take advantage of the heat differential between various layers of rock. Maybe a Stirling engine? I'm thinking like a long thin tube filled with liquid that boils at low temps. The liquid would boil, expand, rise up through an insulated tube, condense at a cooler layer and circulate back down. A little generator could use the constant motion to power a house.

comicjk 5y ago
Deep holes are expensive. Oil drilling, the cheapest kind of drilling since it's very common and in soft rock, costs $100-$200 per vertical foot.* A 2 km hole would cost $650,000 - $1.3M. It would not be economical to do this for one house. Then there are operating costs: operating a power plant on the surface is very likely to be cheaper than operating one underground, and temperature difference is bigger. All in all, a traditional geothermal plant (utility scale, at the surface) looks like that for good reasons. *https://www.oilgasequity.com/resources/drilling-completion-facts/ https://www.oilgasequity.com/resources/drilling-completion-f...
tootie 5y ago
Residential geothermal heat pumps are commercially available. Generating electricity is possible but less practical. Using it to heat and cool your home without fuel is very doable. https://www.energy.gov/energysaver/choosing-and-installing-geothermal-heat-pumps https://www.energy.gov/energysaver/choosing-and-installing-g...

turtlebits 5y ago

IMO, geothermal doesn't really make sense. It's expensive, and the heat gradient isn't huge- you have to drill or dig huge trenches to make up for it. Solar water heating is extremely efficient (and less complicated), but I have never seen it in the US. As for cooling, if it's hot out, the sun is probably out- solar PV with AC/heat pump should be fine.

olivierlacan 5y ago
I've seen solar water heaters routinely on roofs in Florida and other U.S. states that get sufficient heat (Arizona, etc.). I'm not sure either of our observations are useful to determine how prevalent rooftop solar water heating is.
- lostapathy 5y ago
  Solar water heaters have really fallen out of favor because to make them robust, they are more complicated than you'd think. It's generally not viable to just run a water pipe onto the roof, due to both freezing and temperature regulation concerns. So you end up with a closed loop system (filled with a glycol solution that won't freeze) and a heat exchanger to get the water into your domestic supply and at a consistent temperature. Not to mention the service issues of having something "weird" on your house as a critical system. Nowadays, we have electric heat pump water heaters that are very efficient, so running that in conjunction with solar panels to generate electricity can make a lot more sense in practice.
  - msandford 5y ago
    I wish it was easy to buy a gas hot water heater that also had a few coils of copper in it so I could plumb in whatever kind of energy harvesting heat source I could come up with. It'd be great to tap into the heat my AC throws off, or a closed loop solar thermal panel, or both!
    - lostapathy 5y ago
      It really is a shame that HVAC contractors want to mark up more efficient or "exotic" options so much higher than the "base" option. I had my AC replaced a few years back for like $3500, with "least efficient we can legally sell". Doing anything else was going to double the price, even though the wholesale cost difference to the next step up was under 20% of that.

berlincount 5y ago

The first geothermal wells in Germany have exhausted their heat gradient; after less than 30 years … so, unless you’re actually in Iceland or the Canaries or something similar, this might not even sustainable for even one full generation …

dexwiz 5y ago
Will they “recharge?” If so, on what time scale?
- Faaak 5y ago
  They can either recharge naturally (i.e. with earth conduction), but it takes a lot of time. Or you can also recharge them during the summer, either with solar thermal panels, or on a small measure, by running your HVAC "backwards" (i.e. cooling your home and thus heating the wells)
  - restalis 5y ago
    The wells would recharge even without Earth's existing surrounding heat reserves. Moon (and Sun) induced tidal forces do manifest not only in the body of water but also in the Earth's crust, and the resulting tension/friction is quite a source of energy/heat.
Chris2048 5y ago
funny question: can they dig deeper basements now?
xscott 5y ago
Conservatively, there's enough heat down there for the current world's energy use for 17 billion years: https://www.wired.com/story/how-long-will-earths-geothermal-energy-last/ https://www.wired.com/story/how-long-will-earths-geothermal-... Considering our sun will explode in 5.5 billion years, that should be good enough.
- 5y ago

tpmx 5y ago

For nordic climates: After running the numbers I was surprised by how little benefit I'd get from geothermal drilling + heat pump for a much larger investment (like $30k including internal fitting of water-based radiators) compared to a regular outdoor air/air heat pump for $2k. Ongoing costs would be like 5-8% lower. Modern air/air heat pumps are awesome.

Retric 5y ago
Local conditions can dramatically change these numbers. In places where the ground temperature is 20C you use dramatically less energy to heat and cool with a ground source heat pump. Nordic countries have minimal need for cooling and high levels of insulation minimize the need for heating. The worst for heat pumps is simply resistance heating which isn’t that much worse than the a heat pump connected to 5C or less ground temperatures. On top of this 30k is on the high end for ground source heat pumps.
- tpmx 5y ago
  > Nordic countries have minimal need for cooling and high levels of insulation minimize the need for heating. I bought this lovely house built in the 1910s... > On top of this 30k is on the high end for ground source heat pumps. Do note that this estimate included the cost for equipping the house with water-based radioators.
  - Retric 5y ago
    Yea, the water based radiators is a different system than the common approach of having a closed ground loop connected to a heat pump. https://en.wikipedia.org/wiki/Ground_source_heat_pump https://en.wikipedia.org/wiki/Ground_source_heat_pump
- briHass 5y ago
  Define 'much worse'. Even basic heat pumps in traditional air/air split systems can achieve COPs of 3-4 above freezing air temps. The modern mini splits can do that well below freezing. Nowhere has electric so cheap that a 2x or 3x reduction in the amount of electricity used to heat wouldn't result in massive savings.

cmiller1 5y ago

> Is This Industry Trying to Punch Holes in the Ground or Virtue Signal? What?