Geothermal Energy Can Be Sexy
by Justin Thomas, Virginia on 09.28.05
You can use geothermal methods to heat and cool your house. If you dig a channel six feet down in the ground under your house, you access an area where the temperature remains relatively constant year-round. To find out more, visit the Geoexchange web site, which has more information that you've ever want to know about this sort of thing. So how do you make it sexy? We'll that's up to you — how to use all the geothermal heat.
From their site:
Studies show that approximately 70 percent of the energy used in a geoexchange heating and cooling system is renewable energy from the ground.
Interesting trick. I think that they are refering to using the ground as a source/sink for thermal energy. If that's the case then they systems doesn't exactly use the energy, it just transports it.
The remainder is clean, electrical energy which is employed to concentrate heat and transport it from one location to another.
I think most of the readers here may find this statement amusing. I did.
Response to previous poster:
They _are_ technically using the energy. (I'm not going to launch into a thermodynamics discussion on conservation of energy.) However, with a significantly large thermal mass you're right. It's easy to ignore.
As an example, if a large number of people used a small lake as a thermal mass to cool their homes in the summer. We can see how this may effect the temperature of the lake. The enviromental impacts in soil or rock below a building are more reasonable and easily ignored.
Question:
If 70 percent of the energy is renewable then what is the remaining 30 percent?
Does that mean that to heat a house they use the thermal mass of the earth to get the temperature part of the way there and then use the fossil fuel (electricity/gas) of choice to get the building remaining amount? Or is the thirty percent the cost of circulating the energy in the system? Or some combination of the two?
The energy that doesn't come from the ground is the electricity used to activate the fans and pump the liquid and all that.
It's not necessarily non-renewable, though. If you have solar panels, a wind-turbine, buy green electricity or live somewhere where electricity comes from hydro/wind/etc (like here in Quebec), it can be pretty much 100% green.
Neither the article nor the responders mention the fact that a closed-loop geothermal home heating-cooling system is 40% to 60% more efficient than the best gas or oil units and has essentially zero maintenance cost. The big problem is that few people know about it!