Small-Scale Geothermal: Ground Source Heat Pumps

[WolfattheDoor]

While doing some research for my website, I came across the idea of ground source heat pumps. I suppose you could call it a small-scale form of geothermal although, if the heat comes from the sun, it would really be a kind of solar heating. On my site, I shall class it as geothermal anyway.

See http://www.est.org.uk/myhome/generating ... undsource/ for info.

[Bandidoz]

Sorry - it's Solar.

The source of the heat is the Sun, not the Earth.

[Andy Hunt]

But then, biomass is really solar too, isn't it?

[mikepepler]

Sorry - it's Solar.

The source of the heat is the Sun, not the Earth.

Depends how deep you go. The usual home systems buried a few feet down are solar heat, but a lot of systems go much deeper and use heat from the earth's core. Some use old mines for example, and having been down a deep old mine in the Peak District and noticed it get warmer near the bottom, I can see why it works.

[Neily at the peak]

even the fossils are solar!

in the long run.

[Bandidoz]

Mike - if you look at the EST page it's clear they are only going a few feet under the surface.

[Joe]

According to the the International Ground Source Heat Pump Association, they're both geothermal and solar. In the "what is geothermal?" section of their website, it says...

Ground source heat pumps (GSHPs) are electrically powered systems that tap the stored energy of the greatest solar collector in existence: the earth. These systems use the earth's relatively constant temperature to provide heating, cooling, and hot water for homes and commercial buildings.

http://www.igshpa.okstate.edu/geothermal/geothermal.htm

[mikepepler]

According to the the International Ground Source Heat Pump Association, they're both geothermal and solar. In the "what is geothermal?" section of their website, it says...

Ground source heat pumps (GSHPs) are electrically powered systems that tap the stored energy of the greatest solar collector in existence: the earth. These systems use the earth's relatively constant temperature to provide heating, cooling, and hot water for homes and commercial buildings.

http://www.igshpa.okstate.edu/geothermal/geothermal.htm

It's still all to do with depth. Soil doesn't conduct heat very well, so if it's within a few feet of the surface it's not geothermal. Some systems drill straight down, rather than laying a flat system a few feet deep, this costs a lot more but it is certainly geothermal.

[Cycloloco]

According to the the International Ground Source Heat Pump Association, they're both geothermal and solar. In the "what is geothermal?" section of their website, it says...

Ground source heat pumps (GSHPs) are electrically powered systems that tap the stored energy of the greatest solar collector in existence: the earth.

It's still all to do with depth. Soil doesn't conduct heat very well, so if it's within a few feet of the surface it's not geothermal. Some systems drill straight down, rather than laying a flat system a few feet deep, this costs a lot more but it is certainly geothermal.

I agree with the above.
According to some of the posts in this thread wind and wave and biomass would have to be classified as solar but we have separate sections.
Geothermal has to be from deep in the Earth by definition.

Read the stuff above and you see that it is electrically powered but not saying where the power came from. Usually it is the mains but it could be wind/biomass etc. Also heat pumps can take heat from air or water or the ground.

Really, all heat pumps are examples of high efficiency use of electricity in that you can get a few times more effect than immediate use of the basic power. As such they are better thought of as efficiency measures or conservation measures for existing power sources. Where do they fit on Powerswitch? They are not a new power source so I suggest in General Discussion.

[mikemutch]

Hi, I'm new to this forum and stumbled across it while doing some project research. I work as an engineer in the heating industry and a large portion of my work is laying out the ground loop heat exchangers.

Based on your references, I assume that you are speaking of the low-temperature closed-loop systems used as an alternative to outdoor heat pumps and not the high-temperature turbine systems. Heat pumps do not generate power and usually pull their power from the main. I have seen several zero-consumption houses that pair the high efficiency geothermal heating design with solar panels and batteries to balance the overall electrical demand to zero.

That being said, I am not certain the term solar applies to this technology. It is for the most part a bio-mass heat exchanger system that aims to get around the efficiency problem of current air-source systems (i.e. in the winter you are trying to exhaust cold air into even colder ambient air). Solar impact is mute since these machines take energy out of the ground and put it back in. In some installations there is actually a net heat gain depending on how many hours it is operated in cooling. If there is no net change in energy (aside from the energy required to operate the machine) can it be solar powered?

[heinbloed]

As Bandidoz said already: Geothermal power is tapped from the inner part of our planet. Heatpumps tapping into the solar energy are discussed here: http://www.powerswitch.org.uk/forum/vie ... 24b3d4861a

Imagine a concrete block/granite block in black, the size of a house, 1,000m3, lying in the front garden. It would heat up during the day, during the entire summer because of it's exposure to the sun. And when tapped into with the aid of a heatpump it will release the stored energy. Would this heat/energy then be called "solar" energy or "geothermal" energy? Think logic.