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Power Earth Science

Tapping the Earth For Home Heating and Cooling 215

suraj.sun recommends a CNet post giving details of a still little-known energy technology: the ground source heat pump or geo-exchange system. This is distinct from so-called geothermal energy, which taps the heat in the earth to provide energy. Geo-exchange is suitable in scale for small industry — the article describes one commercial re-development of an old mill into apartment and commercial space that put in a geo-exchange at about half the cost of traditional fossil fuel-based alternatives. Even some individual homeowners are opting for this green method of heating and cooling, at a premium in price of about 50 percent (but costs are very much per-project, largely because drilling is involved). "Rather than use underground heat, geothermal heat pumps attached to buildings capitalize on the steady temperature of the ground or deep water wells. In effect, they treat the Earth like a giant energy savings bank, depositing or withdrawing heat depending on the time of year. "
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Tapping the Earth For Home Heating and Cooling

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  • "little known" ??? (Score:5, Insightful)

    by Gothmolly ( 148874 ) on Sunday January 18, 2009 @03:30PM (#26508423)

    Ah yes, kdawson.

    This technology is HARDLY little-known, but places where people need lots of heating and cooling (the Northeast) are also places where electricity is uber expensive (thank you Greenpeace), so heat pumps aren't worth the $$.

    • by Wandering Wombat ( 531833 ) <> on Sunday January 18, 2009 @03:36PM (#26508479) Homepage Journal
      Beat me to it.

      I work in construction and land development in Western Canada, and every single project we work on uses geo-exchange systems, because we get huge tax incentives to utilize energy-efficient technologies (and as strata owners, we still get to charge standard amounts for utilities). This isn't a big city, and there's THREE places that offer geo-exchange services.

      Maybe it's just "little known" where people "don't care".
      • by JWSmythe ( 446288 ) * <jwsmythe@jwsmy[ ].com ['the' in gap]> on Sunday January 18, 2009 @04:00PM (#26508673) Homepage Journal

            Actually, there are lots of people who have no idea that this can be done.

            I live in Florida, and very few people that I've spoken with know anything about it. I haven't been able to find anyone that installs it either, but I'm not looking so hard now that I don't own a house any more.

            There are quite a few interesting variations on this. I won't bother mention the well system, since that's what the article talks about. :)

            One was a dry system, where you simply needed a series of tubes (intentionally said for Sen. Stevens) buried in a horizontal plane at about 10' to 20' deep. You can pump a liquid for a heat exchanger, or even just air, to stabilize the air temperature at about 60F degrees. There are all kinds of options on this. A heat exchanger, or even circulating home air through have both been done successfully. Adding a small amount of outside air can raise or lower the temperature as needed. If 65F is too cold, say 10% outside air could raise that up to 75F.

            Another uses river or lake water. This would depend on your climate to if it would work really well. A friend of mine lives beside a lake that's between 20 to 30 feet deep. Her air conditioner also works very poorly. I introduced the idea of an open loop system, where it would pump water from the lake, through a coil and back to the lake. It would need some degree of large debris filtering, but not a lot (try not to suck up the Loch Ness monster). The coil at the house would simply recirculate just as the regular air handler in the house would, except the coils would maintain about 60 degrees because of the lake. When it's close to 100 degrees outside, and the lake water is in the high 60's at the bottom, a 75 to 80 degree house is a welcome temperature. :)

            Unfortunately, most people look at it as "but, everyone else has a .....". Some people were worried about a reduction in their resale value, because if they sell their home, now there's a "nonstandard" system there. Who would want a house with an almost free heating/cooling system?

            A freon free, low energy system, that takes advantage of the difference in air and ground/water temperature is a wonderful thing.

            This wasn't news, and I wanted to say so too, but people need to be exposed to the idea.

        • by TheLink ( 130905 ) on Sunday January 18, 2009 @04:16PM (#26508815) Journal
          You could remove the need for debris filtering by having a closed loop at the cost of reduced efficiency.

          For example you could fill a closed loop with water, and then put one end of the loop (with coils etc) in the lake, and then the other end of the loop either gets welded to the airconditioner coils (to help make the airconditioner more efficient), or is used as you suggest.

          Of course you'd still have to clean the end stuck in the lake- stuff is likely to still grow on it.
          • by samkass ( 174571 ) on Sunday January 18, 2009 @07:20PM (#26510469) Homepage Journal

            I recall reading about someone in Hawaii doing something like this in order to both generate electricity and clean water by essentially using the deep ocean as the heat sink then the temperature differential to generate electricity (and the condensation for water). Apparently once you got the fluid moving it took less energy to pump it than you could generate with the heat differential in a tropical ocean island.

            • Re: (Score:3, Informative)

              by tylernt ( 581794 )

              I recall reading about someone in Hawaii doing something like this in order to both generate electricity and clean water by essentially using the deep ocean as the heat sink then the temperature differential to generate electricity

              Ah yes, OTEC []. Has a somewhat high cost per kWh, but a neat technology in any case. You could even make a GTEC (same thing but with Ground instead of Ocean) power plant using a sufficiently large closed loop in soil, or a sufficiently large aquifer.

          • by gerf ( 532474 )
            People in this area, Midwest, often build ponds when they build a new house in a rural area, and lay a closed loop in the bottom of the pond for heating/cooling. The only thing people need to be careful about is how deep things freeze, either in the pond or with the in-ground systems.
        • by sribe ( 304414 )

          The coil at the house would simply recirculate just as the regular air handler in the house would, except the coils would maintain about 60 degrees because of the lake. When it's close to 100 degrees outside, and the lake water is in the high 60's at the bottom, a 75 to 80 degree house is a welcome temperature.

          60 degree coils would not even get you close to 75-80 in the house. Exchange efficiency, volume of air, number of BTUs coming in through roof & walls & windows & doors, yadda, yadaa. Not. Even Close.

          • by JWSmythe ( 446288 ) * <jwsmythe@jwsmy[ ].com ['the' in gap]> on Sunday January 18, 2009 @06:40PM (#26510009) Homepage Journal

                That would all depend on the size of the heat exchanger, and the duty cycle.

                If, for the sake of argument, the typical duty cycle of a functional unit is 50% with say 12sq/ft of surface area on the evaporator, at 45 degrees at the evaporator. If you had 60 degrees at the evaporator, but increased the size to say 24 sq/ft, and the duty cycle to 90%+, it should be no problem. Consider that a system like this would require a pump similar to a swimming pool pump or smaller, which most people that have pools run for 12 hrs/day every day. A system like this wouldn't need to run at 90%+, but it would have that ability.

                In reality, it's not even required to run a pump on a system like this. There's a university (I can't remember who off-hand, but a big one) that is currently using a system exactly like this. They don't run pumps, the entire system relies on convection. The cooling itself is free, where the should have huge chillers, lots of freon, and huge power bills. They do still require power to run the fans for circulation inside the buildings, but that's it.

                For an ad-hoc system, I made the assumptions of double the size for the "evaporator", and one 1/2hp swimming pool style pond pump, that was able to handle small debris, with a bypass. If convection did it fine, then the pump was a waste. Even still, when I estimated the costs, and I am good at providing complete estimates, it was less than half the price of purchasing a new HVAC.

                But, your arguments are valid, and a good example of why people aren't willing to step away from what everyone else has. "Oh, that could never work."

                The same could be said of a Peltier/TEC based refrigerator for your car, yet they not only work, but people are very happy with them. Oddly enough, everything I've mentioned is not theory, but working proven fact, that has been implemented. Unfortunately, not widely, because people are afraid to change.

            • by jbengt ( 874751 )
              Most A/C unit water coils (nit pick: there is no evaporator coil where you're using water cooled by the river or lake instead of DX) are designed on a dT (temperature difference) of around 10F to 15F between entering water temperature and leaving air temperature for practical reasons. That would mean a 60F entering water temperature would result in a leaving air temperature around 70F. This is not cold enough to do a significant amount of cooling, assuming that you're trying to maintain an indoor temperat
              • Well, when it's over 95 every day, 70 degree air wouldn't be bad. :)

                We have high humidity during the summer here, so it works out pretty well.

                Here's some weather stats for the area, as found on (the first place I found with a Google search that showed them). My apologies for the formatting. You'll figure it out. :)

                If it could hold 70F at the coils, it would get us through the worst months (the summer), and provide cooling. Outside of the summer, so
          • That's probably 30-40 degrees cooler than the outside air the Air conditioner's evaporator coil is usually cooled by.

        • by squoozer ( 730327 ) on Sunday January 18, 2009 @05:39PM (#26509493)

          This technology is fairly well know in the UK and it's getting more popular everyday. The main problem with it is the cost of drilling (apparently it's about double the normal price at the moment because of the Olympic games - everyone that has a drill is down there laying foundations in Londons rubbish soil) as most people don't have enough garden to lay shallow pipe work. Longer term though if a lot of people switched to this technology we would need to upgrade the electricity grid.

          • Would we though?

            I don't know how it is there, but in the US an awful lot of people here run air conditioning, heating, and heatpumps (A/C that runs in reverse to make heat above 40F outside), that all run on electricity.

            There are some areas that do have a natural gas infrastructure, so they usually heat on that. I just haven't happened to live in too many.

            In the summer time, pretty much every building in the US has an air conditioner running, eith

          • by yabos ( 719499 ) on Monday January 19, 2009 @07:55AM (#26514565)
            I think it's highly doubtful that the electricity grid would need to be upgraded. Think of the demand in the summer due to A/C. It might be different in the UK but in North America there's a huge electricity draw due to A/C in the summer. Geothermal heat pumps are more efficient at cooling than an air to air(i.e. central air, or external air to air heat exchanger) A/C unit. Thus the demand for electricity in the summer would be lower than A/C if everyone was using geothermal exchange.
        • by deragon ( 112986 ) on Sunday January 18, 2009 @06:14PM (#26509787) Homepage Journal

          Since we are on the subject, Toronto did something similar at a larger scale:


          • Re: (Score:3, Informative)

            by JWSmythe ( 446288 ) *

                That's a beautiful example. And, they're still using the water for drinking, which is perfectly safe, since they're running it through a heat exchanger for the system, not using it directly. :)

        • by Anonymous Coward on Sunday January 18, 2009 @07:58PM (#26510807)

          I to live in Florida and have a ground water heat exchange system produced by ColdFlow.
          My system is old enough I don't need to used an enclosed loop. Nice thing about that is every time the unit is running my yard is getting watered too. These systems are very efficient and with being in a cinder block house my electric bill runs about $100 a month.

          •     Wow, a good AC post. :) Thanks!

                I don't see the unit you're referencing right off, but I'm pretty sure I know exactly what you're talking about.


        • buried in a horizontal plane at about 10' to 20' deep.

          This made me think of Winnipeg where I used to live. It gets so cold there in the winter they bury the water mains around 14 or 15 feet down to avoid frost heave. And then they still sometimes have breaks in the line. When it is 35 or 40 below zero (f or c... not much difference at that temperature) and water is bubbling up from the ground from a major water main... an ugly thing. I guess they can make the horizontal plane for those tubes another

          • Re: (Score:3, Informative)

            by JWSmythe ( 446288 ) *

            Ya, if the climate dictates, you'd have to make it deeper. :)

            I did a little more research on this today. I lost my old bookmarks (switching computers too much, and reinstalling for fun), so I don't have the good sites. I did find a couple pages on Wikipedia though. Search "Ground-coupled heat exchanger" and "Geothermal heat pump".

            I was talking to a friend in Alaska about this. A long time ago, I had read about setting up for the nuclear tests at Amchitka, Al

      • Common in Finland (Score:4, Informative)

        by AliasMarlowe ( 1042386 ) on Sunday January 18, 2009 @04:32PM (#26508963) Journal
        They are also quite common in Finland. Usually, a network of pipes is laid about 2 meters below ground level in the garden as the thermal reservoir (in less extreme climates, one meter deep may be enough). They have higher capital cost than the air-to-air heat pumps, but generate less noise and continue to operate even in very cold weather - unlike most air-to-air units, which get into trouble below -20C.
        • They're becoming more common in Scotland too. We have relatively cheap electricity provided by wind, hydroelectric or nuclear power stations, and we've got the space to spread these things out. They work, too. In Scotland's mild climate (never much colder than 10C, never much hotter than 20C) they work pretty well.

      • by Zadaz ( 950521 ) on Sunday January 18, 2009 @08:04PM (#26510863)

        We've been getting virtually free heating and cooling on our 64,000 cubic foot storage building for 20 years. We simply ran a 30 foot extension from the drainage tile in the neighboring field and put a fan on the end of it. Constant 60f air. Paying electricity for a medium sized fan beats the hell out of $3,000+ heating bills in February when it gets and stays below zero or August when it gets above 100f.

        If a farmer could hack this together from spare parts 20 years ago, I can only hope that the technology has gotten much better since then.

      • Yeah, I grew up just outside of Columbus, OH, and our circa 1970 rural home had an electric heat pump, and a lot of our neighborhood did. I remember ads in Columbus with a little jingle "The Electric Heat Pump- It Heats, It Cools, and it Saves" airing on network TV and radio through the early 90's. Call up any HVAC contractor in the midwest and ask them what your options are for heating and cooling a new home installation, and they'll probably list heat pumps as an option. It's hardly obscure.

        Most peopl
    • by ach1lles ( 671687 ) on Sunday January 18, 2009 @03:41PM (#26508531)
      Its been around since at least the 1940s. The building I live in (downtown Austin) uses it and it was built in 1938.
    • by artson ( 728234 ) on Sunday January 18, 2009 @04:11PM (#26508773) Homepage Journal
      When I built my house in 1985, I built a passive solar home (three sided, two-story concrete box with south facing glass and air conduits built into an insulated slab). We placed four solar hot water heaters on the roof as well. The house has repaid the investment many times over, but my one regret is that I allowed myself to be talked out of putting in a geo heat pump system. At the time the experts told me it was too expensive for the projected return. They were wrong of course.

      I don't know much about accounting, but it has always seemed to me that carbon cap trading schemes are just a gigantic boondoggle that allow bad actors to continue acting badly. For my money, if governments (Canadian in my case) want to encourage green technology and lower the country's carbon footprint, then they need to very strongly encourage geo heat exchangers in new construction and particularly for green renovations. Solar heating is not always possible, especially this far north, but geothermal exchange is always there.

      As a post script, for anyone thinking of installing solar hot water panels on their roof, think again. If it is possible to mount them at ground level on a rack, you achieve two things: A. no holes in your expensive roof, and B. it is much easier to maintain them at ground level.

      • What cap and trade systems are is a way to allow markets to most effectively allocate the costs of and pollution caps or reductions. If the government is going to mandate a pollution reduction, it would cost some firms so much they would go out of business. While that is ok to some people, it is not ok to most, and especially not to those whose jobs are at that company. But they may be able to buy pollution or carbon credits from another company that can more easily reduce their pollution. That way the over
    • by WindBourne ( 631190 ) on Sunday January 18, 2009 @05:56PM (#26509603) Journal
      The heat pump that you are talking about has the condensor in the air. That is a horrible choice because yes, parts of the east (and midwest) can hit -40F (or C). If you are heating to say 70F, then you are looking at 110F difference (or ~50C). That IS inefficient and you are better off just doing straight heat from electricity.

      But a geo-thermal HVAC is different. The condensor is piping that is 5-10' down in the ground. The temps are around 55-60F. IOW, you are pulling with maybe 18F/5C range. That is EXTREMELY efficient. In fact, if American were on these, our cooling in the summer would use something like 25% less electricity and our heat bill for the majority of the US would be a fraction of what it is. Even here in Colorado, a front range home who spends 150 for gas heating (a cold month) would expect to only pay about 50-60 for the heating.

      One of the nice things about this, is most of the east coast's fuel oil actually comes from Venezula. If the east coaster would switch to this, we would see our imports from Venezuela drop to about 1/4 to 1/3 of the current amount (Venezuela oil is apparently low grade with lots of sulfur in it; pretty much used for diesel and home heating oil). BTW, EU makes heavy use of Russian natural gas for heating (which is why these games come into being during these times). The best thing that the west can do is move homes to geo-thermal and for American insulate better.
      • BTW, EU makes heavy use of Russian natural gas for heating
        And for electricity generation which means we get hit with a double whammy when the gas supplies are disrupted.

        Lukilly afaict our supplies in the UK come as LNG so we brits have avoided the affects of russias squables wit it's neighbours (though if there was a cold war 2 we would really be in the shit).

    • by rasjani ( 97395 )

      Maybe its the Euro thang ... you know, those pescy 's but here in Finland where we really do need need electricity for heating, we kinda use these to cut down the costs..

    • NO. Ground source heat pumps take advantage of the fact that the ground temperature is fairly constant year-round (equal to average annual temperature). Since a heat pump is compressorized, it takes about 30% of the input energy to heat a space relative to resistance heating (above ground temp). That is thermodynamicslly comparable to burning oil, but with the benefit of the higher input temperature.

      Heat pumps are only effective with cold-side temperatures over 40, which works for ground-source.

      In the su

    • by fermion ( 181285 )
      electricity is uber expensive (thank you Greenpeace)

      i am not sure how greenpeace makes energy expensive. This is supply and demand. If many people choose to move to an area where it is cold or very hot, and then build homes that are large and difficult to keep temperature controlled, then that is no fault except the idiots who do such things. Combine this with the upscale population who does not want power plants in the back yards, or coal or nuclear fuel moving through the area, then electricity is ex

      • Re: (Score:3, Informative)

        by drinkypoo ( 153816 )

        Greenpeace is one of the biggest impediments to building new Nuclear plants in California where they are needed. Coal plants put more nuclear material into the air every year than all the nuclear tests and accidents EVER combined. I know a desk-rider and a former smokestack-climber in the pollution regulation industry and they both let me know in no uncertain terms that you can find people polluting over the EPA standards (whether those standards are even acceptable is a matter for debate) as fast as you ca

  • My dad has a couple exchangers outside his house I've often marveled at the "efficiency", particularly when they are covered in snow, or basking in the sun on a forty degree centigrade day.

  • by Anonymous Coward

    Be warned - this won't work well in all kinds of ground. We've had such a heating system installed in our 200m house about 20 years ago (Germany, with our oil prices we had to get creative a bit earlier than ppl in the US) and we had a lot of trouble with freezing probes (the things that go into the groud) because in the karst (ground with lots of lime in it and thus lots of small caves) they wouldn't keep proper contact with the earth.

  • by Timo_UK ( 762705 ) on Sunday January 18, 2009 @03:52PM (#26508637) Homepage
    Here in South Germany about 25% of the new houses built in our neighborhood have it. Old hat. If you use your garden as the storage medium your plants will flower later than your neighbor's....
  • What about DX? (Score:5, Interesting)

    by unixluv ( 696623 ) <unixluv @ g m> on Sunday January 18, 2009 @03:56PM (#26508655)

    This technology has been around for some time, but it fails to generate much PR. You can get a measley $8000 US federal tax credit for installing one. A few enlightened states (not mine) will give you some additional tax credits for installing one.

    The expensive part seems to be drilling the earth and laying the hose. However, what they fail to mention is that once its installed, it will last 50+ years.

    The parent also mentions open and closed loop, but fail to talk about direct exchange aka DX, which would make more sense for a lot of people.

    From []

    "The direct exchange (DX) system is a series of copper tubes buried 4 to 6 feet below ground level. Refrigerant gas is then fed through these tubes creating a direct heat exchange between the temperature of the ground and the heat transfer medium, which in this case is the refrigerant gas. Because of this direct exchange feature these systems operate at considerably less operating cost than water source systems and because they do not require the additional water pumping cost and, DX does not suffer the heating or cooling loss associated with transferring the water temperature to the refrigerant as is common with these systems. DX is also cheaper and easier to install as it requires no well drilling or plumbing costs. As copper is a more efficient heat transfer medium than PVC pipe as found in water source, trenching costs are less due to less ground mass being required by DX." [] []

    • Re: (Score:2, Informative)

      by Anonymous Coward

      Live in upstate NY - turned on our ground-source closed-loop heat pump end of November 2008. So far, so good.
      Last year when we bought the system nobody was talking about DX (and in this neck of the woods, they're still not.)

      Couple of things I would speculate about with respect to DX:
      1 - copper pipe is MUCH more expensive than plastic geo-tubing and susceptible to oxidation and mechanical failure (e.g. you can punch a hole in a copper pipe pretty easily.)
      2 - the refrigerant is likley NOT to be environmentall

    • Re:What about DX? (Score:5, Interesting)

      by rhakka ( 224319 ) on Sunday January 18, 2009 @04:16PM (#26508817)

      DX systems suffer because they are burying copper in the ground (which is often aggressive to copper), and then pumping refrigerant through them. any puncture or breach would cause a leak of refrigerant instead of non toxic glycol solution.

      DX and "Pump and Dump" geo-exchange systems are both, IMHO, likely to be outlawed in areas with environmental and building codes. Existing systems would probably be grandfathered but in the end I believe closed loop well or "slinky field" type systems will end up the winners.

    • Re:What about DX? (Score:5, Interesting)

      by kimvette ( 919543 ) on Sunday January 18, 2009 @04:16PM (#26508819) Homepage Journal

      How does the lifetime compare to PVC though? I've seen PVC that has been buried for 30 years and looks absolutely brand-new (the above-ground portions though - not so much thanks to UV). How does copper compare, since copper corrodes?

    • Re: (Score:3, Interesting)

      by jbengt ( 874751 )
      <nitpick> In the HVACR industry, "DX" stand for "Direct Expansion", The thing you're referring to needs a different abbreviation. </nitpick>

      I know this system has been used, but there can be some problems with it.
      Copper piping can have a short life in many soil types.
      There will be more refrigerant in the system, which can add some complications and expense.
      I wonder how they handle oil return when operating in the heat pump mode?

  • by Anonymous Coward on Sunday January 18, 2009 @04:00PM (#26508679)

    Consider that heat pumps give you on average 3 times more heating or cooling per unit of electricity over resistance heating, for example baseboard heating.

    If you ignore the mindless Greenpeace types, and your power is from nukes (like in France) there are no greenhouse gas emissions at all and the air stays nice and clean. Likewise, if you live in the Northwest, where hydro makes a great deal of power and electricity is cheaper and cleaner yet.

    One of the big problems with conventional heat pumps is that the coils can ice up in damp cold conditions, like the Northeast USA when temps are 35 degrees F and below. If you ground source, there is no defrost cycle needed, and no noisy fan. You have probably seen a heat pump at some point blow a huge ball of steam off on a cold day at some point, that's the defrost cycle.

  • More Articles (Score:3, Interesting)

    by bosef1 ( 208943 ) on Sunday January 18, 2009 @04:12PM (#26508781)
    The Washington Post had an recent article [] about this technology being applied in the Washington, DC, area. Slashdot has also featured [] articles [] on similar technologies that use deep water from large lakes or the oceans themselves.
  • by G-Man ( 79561 ) on Sunday January 18, 2009 @04:15PM (#26508805)
    ...I would also point out that Bush's Crawford Ranch [] uses a geothermal heat pump.
    • Re: (Score:3, Funny)

      by ScrewMaster ( 602015 ) *

      ...I would also point out that Bush's Crawford Ranch [] uses a geothermal heat pump.

      Ah yes ... but does Al Gore's?

    • by ArcherB ( 796902 ) on Sunday January 18, 2009 @07:27PM (#26510531) Journal

      ...I would also point out that Bush's Crawford Ranch [] uses a geothermal heat pump.

      SHHHHHHHHH! You can't say anything at all good about the president. At least not until after inauguration day!

      Seriously, I find it sad that we have an article about geothermal heating and cooling that is used by the private residence of the leader of the free world and it's not mentioned. Seriously, you'd think the article would have brought it up.

      Has Bush Derangement Syndrome gotten so bad that saying anything good about Bush is taboo? Or was this a simple, innocent oversight?

      • Seriously, I find it sad that we have an article about geothermal heating and cooling that is used by the private residence of the leader of the free world and it's not mentioned.

        Maybe the omission wasn't part of a sinister agenda to deprive W of his due, but not unlike recent Republican distancing from the sitting President. It wouldn't be the first time someone assumed that affiliation with the current leader of the free world might not be the best promotional angle.

        Has Bush Derangement Syndrome gotten so

  • by Anonymous Coward on Sunday January 18, 2009 @04:19PM (#26508841)

    I bought a house in Minnesota (cold winters, hot summers) that was a part of a pilot program in the 80s by Northern States Power (now Xcel Energy), whereby the installation cost was subsidized by NSP for this home and a handful of others.

    Upon learning about this from the previous owners, I was naturally concerned about the system's efficacy at heating and moreover cooling the split-level home as compared to traditional gas furnace and air conditioning. It wound up performing identically on both counts, providing as much heated or frosty air as desired seasonally, all for only the price of operating the heat pump; I believe the annual electric cost was roughly $80/year.

    To top things off the house was furnished with a traditional gas furnace as a safety backup.

  • Utah uses GSHP for almost every school. It saves them a grundel, but takes years to pay off.

    Seriously though, burying your buildings or simply building them underground would be MUCH more efficient. Ammunition bunkers I used to go to in Hawaii or now in Utah were always cool in the summer and kinda warm in the winter. And hella insulated.

  • Absolutely (Score:2, Interesting)

    My parents built a new house off the beaten path almost 4 years ago, and opted to go with geo-exchange because natural gas isn't available in their area. The system costs significantly more than a standard one, but heating and cooling costs are HALF of what they were at their old house, which was significantly smaller. According to some back-of-the-napkin numbers my dad crunched, they should hit the break-even point after less than 15 years of use.
  • I wanted to (Score:5, Informative)

    by JediTrainer ( 314273 ) on Sunday January 18, 2009 @04:43PM (#26509045)
    Recently we installed a new furnace (Ontario, Canada). My wife and I had it priced out.

    Turns out that although there were several grants we could receive, totalling $7000 approximately, it was still not worth it.

    By the time all was said and done, it would have cost $30k to install. They would have torn up our lawn, which would have necessitated new landscaping. They also couldn't guarantee that they wouldn't crush our water and sewage lines with the drilling trucks.

    All in all, it wasn't 50% more expensive. After rebates, it would have been about 4 or 5 times what a 96% efficiency natural gas furnace cost us.
    • by Zerth ( 26112 )

      Only 5 times the cost?

      How much cheaper was the yearly operating costs? 5x install sounds like it could pay off in just 5-10 years.

    • From everything I've head read or heard, going with a DX system makes a lot of sense if you are building new construction. It is easier to install without having to worry about the before mentioned problems of hitting existing pipes and landscaping. But for existing home construction, it's questionable.

      Some day when I do build a house, the two things I want are a DX heating/cooling system and solar panels. Lump those costs in the home and use the extra money from what would have been spent on utilities t

    • by dieman ( 4814 )

      Exactly. I did a 'hybrid' air source geothermal/gas system and it was still at least 3 to 4 times cheaper. I will make up the cost of the air source heat pump in 4 or 5 years, easy, too. Plus I reduced my GHG by about 30% using 'green' power purchases for the heat pump power. This is in Minneapolis too, no slouch to cold temperatures. All the AHSP needed was a little more space, not an entire tear-out of a section of my yard. I'd love to do geothermal, but its really not a solution for people just try

    • It all depends on where you live. I live in an area that was once old river bed and there is a lot of water movement through the old gravels just 5-10 metres below the surface. For me, drilling to 20 metres would be almost as good as placing the heat exchanger in the river.
    • I second your remarks about the costs not being anywhere near "only 50 percent more than a conventional system." A colleague of mine lives on a small exurban farm, does hot water heat with LP gas, and supplements with a wood stove. His hot water furnace gave its death rattle and he had to put in a new system. His replacement hot water furnace as $8000 as in eight-thousand-freakin'-dollars. I put in a new hot-air furnace (condensing, variable-speed DC blower, top-of-line) and a new 13.5 SEER central air
    • Fat lot of good that gas furnace is going to do for you when the Energy Return on Energy Invested of gas production in Canada goes below 1:1 in 2014 and production collapses. []


  • Tapping the Earth For Home Heating and Cooling

    I've been tapping and tapping, and all I got for my trouble was a broken fingernail.

    • Re: (Score:3, Funny)

      by CarpetShark ( 865376 )

      I've been tapping and tapping, and all I got for my trouble was a broken fingernail.

      This is why you should leave it to the professionals. I bet you just went ahead and arrogantly acted like an expert without even buying a proper pair of tap shoes.

      • I've been tapping and tapping, and all I got for my trouble was a broken fingernail.

        This is why you should leave it to the professionals. I bet you just went ahead and arrogantly acted like an expert without even buying a proper pair of tap shoes.

        No, I just figured the ground would warm up when I tapped it.

  • I have one. (Score:5, Interesting)

    by haeger ( 85819 ) on Sunday January 18, 2009 @05:19PM (#26509353)

    About a year ago we installed one of these in our house. The temperature around here varies between -15 C to about +30 C (get with the metric program people) and our heatpump is working wonders with our heating and economy. It cut the costs down to 1/3 of what it used to be and will have paid itself off in less than 5 years with current prices.
    We drilled about 200m down which gives the best performance for the size of our house.
    Also we put a large watertank that the heatpump warms up which increases the lifespan of the pump and our next project is to put solar panels that will heat the watertank during mars-oct, thereby increasing the savings even more. It will also "reload" the hole/well that the heatpump takes its heat from increasing the efficiency during winter.
    Now if I could only produce electricity somehow to power the heatpump (or parts of it) things would be awsome.

    I'm amazed that more people don't use this technology. In my opinion there shouldn't be an energy crisis anywhere as all the technology we need to fix things are already availible. More or less anyway.


    • Re:I have one. (Score:4, Insightful)

      by Fallingcow ( 213461 ) on Sunday January 18, 2009 @07:58PM (#26510809) Homepage

      I'm amazed that more people don't use this technology.

      Like most things, it's not for everyone.

      Our quote for installation here was about $25,000 for a system that would heat/cool a 3000sqft house.

      The house cost us less than $100,000, and we probably won't be here more than 3 years or so. No way in hell the house's value will be increased by at least the difference between our savings and the remaining cost of installation when we sell. Conclusion: we would lose money putting in that system.

      It's sad, but unless these kinds of improvements become more highly-valued by home buyers or people stop being so damn mobile, for many of us it's just not worth it to make long-term energy efficiency investments in our houses.

      • Re: (Score:2, Interesting)

        by jfanning ( 35979 )

        We investigated one here in Finland when we built our house four years ago. They were starting to become very popular about that time since electricity prices just keep going up.

        But in any event we were advised not to go that way since the investment would be too large for a house our size (total room area of 130 sq metres).

        So we have a air exchange system that heats the incoming air using the outgoing air. It is mandatory in Finland that all new houses have a total air exchange approximately every two hour

    • I have one too, a retrofit on my existing house. It eliminated the external (and massively undersized) air conditioning unit, and runs much more quietly than the gas system did. And the gas system was only 6 years old when I replaced it, so it wasn't a dinosaur.

      One piece of cool tech I haven't seen mentioned directly is that the heat pump itself creates heat; this is siphoned off by a water-based heat recovery system into a secondary hot water tank. When the primary hot water tank needs input water, it gets

  • The Goethermal Heat Pump Consortium [] is an industry group. Their site is full of information resources, blogs,and forums. [] -- over 7500 published book reviews.

  • by chrispitude ( 535888 ) on Sunday January 18, 2009 @06:06PM (#26509709) Homepage

    Side note to the OP, the phrase "geothermal" to most homeowners does mean ground-source heat pump technology, not the stuff they use in Greenland.

    I have a modest 2000sqft home in northeastern PA (Poconos area, I'm 8 miles south of Camelback ski resort). I had two contractors out to quote ground-source DX (direct exchange) systems, and both quotes were in the mid-$20k range. Too rich for my blood.

    I went with a Hallowell cold-weather heat pump [] for pleasantly less than half that. The Hallowell is mostly sold in Canada and upper New England, but it's been slowly working its way south. When I called them to ask about my application, the guy laughed and said "Man, you're in the tropics!"

    It's only been running for a few weeks now, but I've been very impressed so far. It hit -3F two nights ago and the heat pump still ran entirely off the first compressors in stage 1 (stage 2 was still not needed). The air coming out of the vents was warm to the touch. In fact, the system has yet to resort to resistance heat down to -3F exterior temperatures. We keep our house set to 66F. I've been able to kick the heating oil furnace and storage tank to the curb. No more timing oil pre-buys against market prices, no more noisy power venters, no more oil storage tank taking up basement space, no more yearly burner tuneups and vent pipe cleanouts. I even get nice 18 SEER air conditioning to replace my builder-grade central air conditioning unit.

    Pictures of the complete home renovation are at:

    my house renovation []

    The entire system is on a dedicated subpanel, and I've put a subpanel meter on it to measure total kWh usage. This will allow me to directly measure operational cost each month.

    Another factor that steered me away from ground-source is balancing the break-even time versus the system lifetime. If it takes me 20 years to break even on the ground-source and the system needs replaced not too long after, I haven't really gained anything. If the Hallowell takes me 7 years to break even and the system lasts 2-3 times longer than that, I've saved quite a bit of money. Break-even isn't everything; it has to be balanced against the expected lifetime of the system. Plus, I'd have to factor in the cost of repairing the yard after the loops were dug and installed. They claim that just a 3' circle of ground is disturbed to drill the loops, but one of the guys eventually admitted the machines rip up the yard pretty bad as they drive around the hole to drill the loops at different angles.

    I found the guys at Hallowell to be very helpful to talk to. I don't work for them and I have nothing to gain. I simply speak as a satisfied customer. For new construction, rolling a ground-source system into the mortgage would be the way to go. For my existing construction with an established yard, simply setting the Hallowell on an outdoor pad was an excellent path forward for me.

    - Chris

    • I'm in Central Wyoming and I'm interested in something like this but I'm also tinkering around with various 'get off the grid' projects and I'm curious how much power generation I'd have to install in order to run one of these.

      So, if you feel like sharing, what exactly is your kWh usage?

  • by Nimey ( 114278 ) on Sunday January 18, 2009 @06:34PM (#26509959) Homepage Journal

    I can't help but wonder about what would happen if a sufficient number of people in an area used heat pumps, long term.

    What would happen if the ground got abnormally warm? Would this cause any problems with ground strength, or soil moisture, or what have you?

    I'm genuinely curious here. Has anyone done a study about this?

    • by DamonHD ( 794830 )


      Have a look at [] where Prof MacKay deals with this.

      In practice you can mitigate the problem (which will only be a problem at all in dense population areas) by capturing solar heat in summer, eg excess not needed for solar hot water, and using that to warm the ground. Then the ground is a straight-forward heat-store, maybe a little like this: []



    • by jbengt ( 874751 )
      When designing the ground-coupled heat pump system, you need to balance the heat gained by the ground in the summer with the heat removed from the ground in the winter. Where they don't balance out, you need to figure that the ground will warm-up (or cool down) over time, and you'll need more heat exchange piping in the ground.
      You're not really adding and removing any more heat to the ground than you would add and remove from the air, only a little less waste heat due to better efficiencies. Since the h
  • This can be done on larger scales, using old coal mines that have been flooded with water. At depth, the water is fairly constant, and the volume of water is large enough, that it can be used as a sink for heat pumps. Here in Nova Scotia, Springhill [] uses old coal mines to help with heating. From wiki:

    The abrupt end of the coal mining industry presented incredible economic challenges to the town. An unexpected legacy and benefit from the closed mines is being realized in geothermal energy. The mines in Sp

    • In bad form, I'll reply to my own post to add a bit more info:

      The difference between the geothermal heat source, and a geothermal heat pump is this: the underground temperatures are not high enough to provide your heating (they're typically 65'F or so, I believe). Pumping 65'F water through your house (after losses along the way) isn't going to do much for you.

      But because it is a constant temperature, you can use a heat pump, with refrigerant, a compressor, evaporator, etc., to extract the heat from it. W

  • by Anonymous Coward on Sunday January 18, 2009 @11:06PM (#26512157)

    I'll get to the point but first a little background.

    It is an odd reversal here, but because sewer rates are so high here and city water metering was the way to measure sewer use. People in the suburbs started drilling wells in my area because it has an easy to get at artesian water table. Without the the use of city water there was no way to tax the sewer use. Got the idea and how it is going to apply?

    So the city in it's infinite wisdom decide that wells were 'verboten' no matter what over the whole area. There is no way that you can get a permit.

    Now you may think that explaining what you want to do to heat your home would get you a variance. Not simply because the city won't budge, but even more ludicrous is they think you will cheat and not put the water back in the ground as that costs more, but will dump the water into the sewer and increasing the water to the plant for free on your side. Thus making you a thief before found to be one. So easier and cheaper for them is to ban wells period no matter how well intentioned you are to green the planet.

    It's to bad I wrote this late as it is not likely to be moderated high enough to get noticed and other point out a similar problem in their area that stops this type of system dead before it lives.

  • Self-powering? (Score:3, Interesting)

    by Zaphod-AVA ( 471116 ) on Monday January 19, 2009 @12:35AM (#26512741)

    I have always thought that combining one of these systems with a passive solar heat storage block and a Stirling engine to help power the pump would be fantastic.

"I prefer the blunted cudgels of the followers of the Serpent God." -- Sean Doran the Younger