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Home Forums General Discussion Geothermal energy Re: Geothermal energy

#63754
Kenwilland
Participant

As far as I understand, there are basically two kinds of useful geothermal energy, one is available in areas such as Iceland where the heat from the earth’s core is available close to the surface, or at least within boring distance. These rocks are hot enough to turn water to steam and can be used to generate electricity in much the same way as a conventional power station. This heat can also heat homes factories etc.

The other kind is made use of in ground source heat pumps. These basically work in the same way as a refrigerator, only the layout is different. Heat from the sun is absorbed by the soil and rocks and leaks out relatively slowly overnight. If you go say a metre down the soil doesn’t freeze even in winter, at least in the uk. This is the heat you are making use of. Laying pipes at this depth corresponds to the inside of your fridge, which is connected to radiators, usually underfloor inside your house, which corresponds to the back of your fridge where all the black pipes are. In your fridge these pipes get warm as they remove the heat from the food you want to keep cold.

Energy is used to compress the gas inside your system before returning it underground, but in return you get three times the energy (rough figures) heat as you put in as electricity, so it can be a cheap way to heat a house if you are prepared to dig up your garden. This electricity could even come from solar panels, PV type, to make the whole system independent of the grid. Car parks are good places to bury pipes because the tarmac or whatever is dark and so absorbs heat well.

Finally it is being used in the UK.