We are currently working on getting a geothermal system installed. Our wonderful president removed the cap on the credit so now a straight 30% tax credit is available on a geothermal system installed in 2009. We have a ridiculously old furnace that is horribly inefficient. I hate even using it but we had to stay warm. How does a geothermal work? I'm glad you asked. :)
Up here on the surface where we all live the temperature is quite variable but deeper underground it stays fairly constant. I remember going to visit Ohio Caverns when I was little and hearing that the caves stayed about 60 degrees year round. Geothermal heating/cooling takes advantage of this property. Loops are laid into the ground either vertically or horizontally and fluid is circulated through them. This fluid absorbs the heat from the ground and circulates it into the home where it is used to heat the air. In the summer, it works in reverse by heating up the fluid in the pipes and dumping it back into the ground.
They are also really efficient. "For heating efficiency, the efficiency of an energy saving geothermal system is known as the COF or Coefficient of Performance, which is the ratio of BTU ouput (amount of heat extracted from the heat source) to BTU input (BTU equivalent of the electricity used as input). ENERGY STAR rated geothermal heat pump systems must have a COF of 3.3 to 3.6 (or greater), depending on the loop type. For comparison, the COF of the best energy-saving electric heaters is 1 (one BTU of electrical energy produces one BTU of heat). The COF of a 94% efficient high-efficiency gas furnace would be 0.94.
For cooling efficiency, the same energy efficiency rating is used as for air conditioning systems, the EER or Energy Efficiency Ratio. ENERGY STAR rated geothermal systems must have an EER of at least 14.1 to 16.2, depending on the loop type. Compare this to only 14 for most standard air conditioning systems." (Extracted from http://www.green-energy-efficient-homes.com/energy-saving-geothermal.html) Pretty cool huh?
It comes at a bit of a hefty price tag or so it seems at first glance. Our system that we plan to put in our house will cost around $20,000; however, after a credit for getting our contact at the Home & Garden Show and the tax credit of $6000 the cost is more around $13,000. When considering this will take the place of both a furnace and an air conditioner (which our house doesn't have right now), the system should pay for itself in savings within one to two years. Here's how I calculated:
Cost of system: $20,000
less H&G credit: (600.00)
less tax credit: (6,000.00)
less cost of new furnace: (5,000.00)
less cost of AC: (4,000.00)
Total remaining cost to be justified=$4,400.00
Here is where the beauty of the geothermal comes in. Since most of the "working" parts are underground and thus not exposed to the elements, the life of the unit is 20-30 years. Almost twice as long as a conventional gas fired furnace. So, that would cover the other cost.
I know not that many people read my blog, but as a huge supporter of green technology I feel it is important to let as many people as possible know that this is out there and possible. Some people at work didn't even know that geothermal was residentially available even though it has been since the late 80's. I'm proud and happy that I will get to put my money where my mouth is, though I think the few people that read my blog know that I try to do that everyday. :) Now we are just crossing our fingers on getting financing for it.