Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?
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. "
This discussion has been archived. No new comments can be posted.

Tapping the Earth For Home Heating and Cooling

Comments Filter:
  • "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 JWSmythe ( 446288 ) * <jwsmythe@@@jwsmythe...com> 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 Yvan256 ( 722131 ) on Sunday January 18, 2009 @04:24PM (#26508887) Homepage Journal

    Slashdot, which is supposed to be run by nerds, still doesn't support UTF-8. Simply use HTML entities next time.

  • by navyjeff ( 900138 ) on Sunday January 18, 2009 @05:21PM (#26509367) Homepage Journal

    What is a grundel, and why would you want to save it?

    A grundel [wikipedia.org] is an Old English bipedal monster or dragon, descended from Cain. I would imagine you would want to save it for yourself in order to keep your neighbor's dog off your lawn.

  • 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.
  • 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.

  • mental diagram (Score:2, Insightful)

    by zogger ( 617870 ) on Sunday January 18, 2009 @08:19PM (#26510949) Homepage Journal

    I don't live in that area anymore and didn't take pictures, but I think you can get it with this mental diagram. It's easy, Just a cheap plug in water pump and they use the existing coil and the squirrel cage blower. You'll need to use adapters to match the sizes on the coil. I guess you could use like a cheap/small used swimming pool pump, I didn't see what they were using, they just said a "water pump", sitting on a little shelf alongside the AC unit in a box. It was remarkably simple. I didn't even pick up on it until I visited their store a few times (normal cool inside like it had regular AC running, small little store) and noticed the water pipelines dropping down from the back of the unit (you could see it from the parking lot), so I went over and checked it out, then asked them about it. The guy who owned the store just took the old AC when it died and modded it. The creek is around 40 or so feet away, runs year round, little trout stream in north georgia mountains, so it is more or less pretty cold even in the summer months. They just drain it in the winter.

    Thinking about it, you could build one with a car radiator and a box fan (measure window to get sizes where you need to put it), same deal, just add the pump, then maybe a little sheet metal shroud to tidy it up so it looked good. I've been meaning to build one myself, we don't use AC here, but I water the garden so much with cold well water that I keep thinking..hmmm..might as well. Just anther project, and I was going to put an underground tap out there anyway to eliminate hundreds of feet of garden hose out on the ground.

  • Re:Cap and trade (Score:4, Insightful)

    by Agripa ( 139780 ) on Monday January 19, 2009 @01:38AM (#26513059)

    As I see it, the big problem is that cap and trade is spectacularly susceptable to rent seeking and regulatory capture [volokh.com]. A carbon tax levied on non-renewable energy to offset negative externalities is much easier to both administer and understand while providing incentives through economics.

  • 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.

I am more bored than you could ever possibly be. Go back to work.