Geothermal Heat Pumps: Are They Right For Your Home?

Baseload geothermal power gets all the attention because it has such enormous potential for delivering low-carbon 24/7 power.

But geothermal heat pumps (GHPs) are every bit as deserving of attention because they are the most energy efficient form of heating and cooling a building over much of this country. And if you power GHPs with a renewable source of electricity, they are probably the best way to eliminate the need for natural gas heating in the winter while at the same time slashing peak demand in the summer.

The U.S. Energy Information Administration released their "Survey of Geothermal Heat Pump Shipments, 2006" last month. It found "that manufacturers shipped 63,682 geothermal heat pumps (GHP) in 2006, a 33 percent increase over the 2005 total of 47,830."

Read the full story

-OR-

More on green energy from the Huffington Post

Comments

[mamacat]

Sounds like it could work. Talk about this technology has been around for decades. I don't know why it hasn't gotten more publicity.

We had a contractor-neighbor 55 years ago who installed a mini-heat pump in his place. He just up and did it on his own because he felt like it. Seemed to work pretty well, and saved him money, even back when electricity was cheap.

[mamacat]

I guess I should clarify my comment. 50+ years ago A/C units that could cool down the whole house were pretty much unheard of. What our neighbor did (and it worked pretty well) was a modification of the heat pump idea. Instead of having pipes that went into the ground, he took water from his swimming pool and circulated it in the house to cool it down. As an added benefit, the pool got heated up. It actually worked, though not as well as a modern whole-house A/C unit. Of course, it didn't do him any good in the winter. Sure made his pool comfortable.

This fellow was a bachelor, and liked to experiment with different ideas. The neighbors were all impressed with his ingenuity, because it really worked.

[DeCapeJack]

Not sure about retrofitting, but building a new house with a GHP make a lot of sense. When I built my place in Delaware in 2005, I spent about $20,000US for the GHP system, which was about twice the cost of conventional heating and AC systems. Of course, the heat pump is run by electricity, and the house, by the way, has about 1700' ft of living space. I also built a well insulated house and took advantage of some minor passive solar heating through a good southerly exposure. My average monthly electric bill is between $50 & $70, winter and summer, and that covers my lights, fridge, GHP, computing, TV's, etc. True, I also use Energy Star rated appliances and mini-fluorescent lights. Many of my neighbors are paying $300 - $400 / month on heating and electricity, so I save at least $300/month. It took me less than 3 years to pay the difference of the GHP vs. conventional heating and cooling. Many states provide a rebate for similar systems, so their return on investment is even more dramatic. The numbers would be no where as good for retrofitting an existing house, of course. But for a new place, its a good strategy.

[sloburnjo]

wolfgang is wrong
coyotew is wright
i live in Montreal, Quebec, Canada your neighbour to the north.
geo thermal is alive and kicking here and i presume in my sister provinces
single family dwellings,multi family condo developments are springing up all over town, in all price ranges.
tax breaks, incentives and government green money is available and many are taking advantage.
and believe me we enjoy real winters and humid summers present one excepted.
chin up my friends, pressure your politicos and change can happen
but then again you guys are afraid to do the right thing

[loki]

Only if you can afford it. and the majority of Americans just cant afford to renovate green. GOing Green is still being used as a profit making trend. Until it get more affordable for everyday people, only those who can afford to pay the higher bills, will be the ones who can go Green. Going Green is a rich mans game.

[Hopalongpoppyseed]

Hear, hear!

[wolfgangmo]

The farther north you go the worse this technology works.

What they are talking about here is not true geothermal [read about Iceland if you want to know what geothermal is and how it can be used]

The units described in this article are in truth a type of forced geothermal where the heat differentials are created by placing energy into the ground to be used at another time. It is efficient but not highly efficient.

We could get much better results at a lower cost by simply going to an 8 inch insulated wall on all new construction using current technology.

Geothermal, real geothermal which comes from the ground rather than forced geothermal which uses energy to place heat in the ground, is a good technology, but it has limited uses otherwise.

The idea of neighborhoods grouping resources to get off the grid as much as possible.

On the bright side there is a new solar cell company which did it's testing at the arctic circle and had great results. And a Japanese company has proven that they are year away from a production on a battery that could power a car that will charge in only 1/2 an hour. The future is here.

[HappyRabbit]

Not a particularly insightful or accurate description of a geothermal heat pump. Here is a very readable description of the newest of these technologies.

[coyote4]

"The farther north you go the worse this technology works."

*
Hellooooooo.............? You know nothing about this. Geothermal is one thing; this is another. This is just a larger and reversible refrigerator.

2 systems:
- air to air heat exchangers lose efficiency in the north as temperatures drop.
- heat pumps that use a ground based "heat sink" do not have this issue because they are deep enough to take advantage of steady earth temps. The ground may be frozen soid at 2 feet, but go deep enough and the temperature is steady.

The cost in this system is in digging and placing the underground piping. The rest is the similar to the cost of a central air conditioner. The benefit is that the system is reversible so that in summer it cools and winter it heats just for the cost of the electricity to drive the pump.

Government subsidies and no-interest loans are needed to drive Green tech retrofits.

[Egalitare]

You're talking apples (large-scale energy production using hot springs, thermal vents, etc.) and oranges (using a residential-based technologies to reduce one's carbon footprint). These are not mutually exclusive, BTW.

Stop trying to be a "purist" and take what solid gains are out there on any and all fronts.

[RememberTheAlamo]

Hi All,

This should be a considered for every new housing development . . . We could place these under the streets. Make loops which everybody could share and turn our neighborhoods into quiet energy efficient zones . . . reducing the the heating/cooling load by 60-75% might make it possible to use solar to run the remainder of the house energy load (maybe).

It comes down to the coefficent of heat transfer (between the pipe and the earth) and the energy (coefficient of friction) to pump the liquid around. If you used a solar pump to accelerate the liquid flow, even when the system is off . . . calculations show the heat transfer would be even more efficient.

Also discovered this form of heating/cooling changed the way a house is designed. We are able to move the liquid to the second/third floor, before the heat exchange . . . this localizes the heating and cooling, meaning shorter ducts and far shorter copper pipe runs. (Less energy loss) Also provided an opportunity to truly "zone" the HVAC.

Would make for some real "green zones".

[KillTheMessenger]

What struck me most about the article is the tiny number of installations. The technology is vastly underutilized.

[RememberTheAlamo]

Hi KillTheMessenger,

Me too . . . but it would appear many of these companies just brought products to market and the distribution channel is still forming.

It is the "ground-loop" geothermal which holds promise. It takes up space, but is buried about 6-9' down. "Slinky-pipe" appears to be the mechanism which made ground loop geothermal doable . . . . will assume must HVAC men don't have small excavators (in the 307-SSR range) to dig the trenches so this is not a one-stop contract.

But we adapt . . . and where there is a market there will be a vendor!

They even have computer programs to size the pumps/pipes!

[jsarets]

New housing developments should have central water plants that furnish heated and chilled water to a few dozen housing units. The central plant can take advantage of economies of scale, minimizing ground-loop approach delta-T and providing large heat pumps with efficient centrifugal compressors and counterflow cooling towers.

Housing units can employ the heated and chilled water in forced air systems or zonal fan-coil units, but because of the long pipe runs, the significantly lower hot water temperature requirements of radiant floor systems would minimize parasitic pipe losses (chilled water is much less of a problem).

During cooling season, establish a nice stack effect by opening a rooftop relief vent that induces natural ventilation through baseboard intakes that add convective heat transfer to the radiant floor. Natural ventilation, all-water thermal distribution, neighborhood central plant, and ground-loop heat exchange. That's how you eliminate over 80% of typical HVAC energy consumption.

[RememberTheAlamo]

Interesting . . . guess we were engineering your "dad's geothermal loop"!

So the central water plant wouldn't use geothermal?