[Jamie]

We usually try to couple a Hydronic Radiant system with a geothermal system for maximum efficiency. Geothermal is an excellent cooler, and coupled with a comfortable, efficient radiant system, it is a great combination.

[Mercani]

I started wondering why sea water is not used for cooling during summer.
Usually seawater is much colder(especially at some depth) than air temperature during summer. We could build a large pipeline to the ocean about 100 m deep and cycle the water through pipelines in coastal cities. (for example Miami). The water would cycle through the needed buildings. Alternatively it could be used as the colder side of AC units. (pumping heat from hot to cold is much more efficient than pumping from hot to hot.)
This requires a new set of pipeline network(similar to natural gas pipes), but I'm pretty confident it would reduce AC use tremendously, saving huge amounts of electricity. AC would still be needed, but used much less.

[Doly]

You still need energy to pump that water out of the sea.

[Tanada]

$this->bbcode_second_pass_quote('Mercani', 'I') started wondering why sea water is not used for cooling during summer. Usually seawater is much colder(especially at some depth) than air temperature during summer. We could build a large pipeline to the ocean about 100 m deep and cycle the water through pipelines in coastal cities. (for example Miami). The water would cycle through the needed buildings. Alternatively it could be used as the colder side of AC units. (pumping heat from hot to cold is much more efficient than pumping from hot to hot.) This requires a new set of pipeline network(similar to natural gas pipes), but I'm pretty confident it would reduce AC use tremendously, saving huge amounts of electricity. AC would still be needed, but used much less.

[mistel]

Here in Toronto the large buildings in the downtown core use the water of lake Ontario for cooling: link

[fsq4cw]

We have been using a geothermal heat pump for almost 2 years now. The money we've saved on heating alone is paying for 2 return airline tickets to Europe - a lot better to burn it in a jet going somewhere on vacation than in our basement and up the chimney!
While others are still debating, 'When's the pay back?' we'll be looking at the Mona Lisa!
More information on this and other related subjects can be found at: link

SR: how-efficient-is-it-magazine.com

[agni]

$this->bbcode_second_pass_quote('Mercani', 'I') started wondering why sea water is not used for cooling during summer. Usually seawater is much colder(especially at some depth) than air temperature during summer. We could build a large pipeline to the ocean about 100 m deep and cycle the water through pipelines in coastal cities. (for example Miami). The water would cycle through the needed buildings. Alternatively it could be used as the colder side of AC units. (pumping heat from hot to cold is much more efficient than pumping from hot to hot.) This requires a new set of pipeline network(similar to natural gas pipes), but I'm pretty confident it would reduce AC use tremendously, saving huge amounts of electricity. AC would still be needed, but used much less.

[strider3700]

Yeah they do that in toronto. I think they where having issues with muscles living in the pipe and blocking it up. Great idea however.

[Kingcoal]

I think geothermal is the way to go. Cheap heat and cheap air conditioning. A guy I work with has a heatpump and a well. He put 2 and 2 together and installed a geothermal heatpump. The unit runs water from his well through the heat exchanger. The only drawback is it needs to have the lime buildup cleaned out periodically, but that is minor compared to the savings. He said his summer air conditioning is practically free for one.

[Keith_McClary]

They have "Geothermal Heating" in Iceland where the rocks underground are hot due to volcanic activity.
But there is also a "Geothermal Heating" technology which pumps heat from underground wells at a temperature a few degrees above freezing to heat houses to room temperature. This uses about 4 times less energy than combustion heating (in cold climates) but the equipment is very expensive ($15,000 more than furnace) and it runs on electricity. Where I live, everyone heats with natural gas and electricity comes mostly from coal. Even with current high gas prices, electricity costs twice as much as gas per gigajoule.
Should I go with this new technology (from Sweden, only a few installations in this region) or stick with the tried and true gas furnace?

[Barbara]

The only thing I know is that George W.Bush in the Crawford Ranch use geothermal technology for heating and air conditioning. I'd stick with the bigoilers...

[nocar]

Keith_Mclary, We installed a geothermal system like you describe here, in the Stockholm area, about 8 years ago. We have had very little trouble.
At that time, it was not possible to combine it with a cooling system for hot days, which it is today. Well, for us hot days is not much of a problems, but putting some heat back into the hole improves the efficiency when the cold weather arrives.

We have a 90 meter hole into the granite bedrock under our house, that was drilled for the installation. That was the most expensive part. If we would install it today, I think we would drill deeper, like 120m. Deeper hole means higher cost for installment, but more efficient heating in colder temperatures. It is used for both space heating and hot water. It is most efficient in not terrible cold weather. Under - 8 C or so, the heat pump must be helped by some extra electricity, but luckily, here it gets that cold only for a few short spells most years.

The system can also be combined with solar water heating, which might be good in your place, but of course increase installment costs somewhat.
Of course, the whole thing runs on electricity. A very import question then is how your electricity is generated. Here it is by a mix of hydro and nuclear, very little fossil fuel. Swedish electricity is inexpensive compared to the rest of Europe. We have saved lots of money on our system - we used to heat by oil, and our oil furnace and tank had to be replaced at that time anyway, so for us you have to subtract that from the installment cost. But an important factor for us was the environment and global warming (even though I often think that I would like a warmer climate here).

If your electricity is by coal, you have to take into consideration the likely price development of coal compared to natural gas. And also environmental aspects. Also the heating system of your house - for us the oil furnace was in the basement, leaking heat into the basement which kept it dry. A few years after installing the heat pump, with a colder and more humid basement we got some mold growing. So we had to install some new radiators in the basement.

[frankthetank]

I was just going to post on this. The new house we'll be moving into has its own well and a large yard with no trees. I was thinking that maybe installing this type of system would be a good choice? Anyone in the states have this? The energy is free in my book, its just the upfront costs.

[Caoimhan]

It is my understanding that if you already have a well drilled at your home location, the process of installing a heat pump is extra simple.

[Elfstrom]

More correct terms for what you are describing are "Ground source heat pump" or "earth energy system" or "GeoExchange".
"Geothermal" has traditionally been used to describe systems using active volcanic-source heat, like in Iceland. Somehow along the way it became used to describe ground-based heat pumps.

Ground source heat pumps have been around for quite some time, and the principle behind it is sound. It is indeed economic. Presumably if you could store energy from solar and wind you could use an off-grid heat pump.
Normally it requires land for you to dig up, but if you're constructing a new building it's even possible in an urban area. The new condo we'll be eventually moving into next year in Toronto uses vertical shafts directly below the condo building for the earth energy system.

[Starvid]

Earth heat pums really rock. Only thing better is district heating and that sadly constitues a natural monopoly.

[Keith_McClary]

$this->bbcode_second_pass_quote('nocar', 'K')eith_Mclary, We installed a geothermal system like you describe here, in the Stockholm area, about 8 years ago. We have had very little trouble. ... If your electricity is by coal, you have to take into consideration the likely price development of coal compared to natural gas. And also environmental aspects. Also the heating system of your house - for us the oil furnace was in the basement, leaking heat into the basement which kept it dry. A few years after installing the heat pump, with a colder and more humid basement we got some mold growing. So we had to install some new radiators in the basement.

[IslandCrow]

I to am looking at ground heat exchange (possibly with some solar panels) to replace an oil furnace in the house I just bought. A few days ago the wife listened to a radio program about a man how had installed a similar system and the only draw back the person could find was the 'investment' costs. At today's oil price it represents a payback in 10 years ---- quite a long time, but if you calculate rising oil prices (and corresponding rising electricity prices) the pay back period is shorter, with significant financial savings 5 or so years down the road.

The problem I am facing is finding the money to make the switch, probably needing to take a loan on top of a mortgage, which as many people here feel is a "NO NO". At least the house came with a full oil tank so I can delay any move until spring. At least then I would be in a better position to asses the risk of keeping with oil heating a bit longer (say one more year) verses taking on a bigger debt.

[Curmudgicus]

Geothermal heat pumps are one of the best ways around to reduce the energy load of a house. It works for heating, cooling, and water heating. It isn't a cheap retrofit, but it isn't too much more expensive in a new house. A colleague of mine in Northern Virginia has it in a 2200 square foot house, and his annual heating/cooling/hot water bill last year was $475. There are some great manufacturers in the US too. If you live in a colder climate, ECONAR makes a great geothermal heat pump.

[Starvid]

Every day there are dozens of ads from earth heatpump companies in my morning paper. The technology is very mainstream and also very popular, especially for single family houses. I believe the payback time is 5-10 years. More info: heat pump