The earth is hot, so why don’t we use that to heat our homes? Geothermal heat pumps try to answer the question by doing just that.
What is a Geothermal Heat Pump?
A geothermal heat pump is simply a device that harvests heat from deep underground. Do you remember the science trick where a hula hoop of water had heat applied to one spot? If you remember, you know that the water started circulating in the hoop.
Geothermal heat pumps rely on that exact same process. Two long tubes are fed deep underground, usually with something connecting the ends together to soak up the earth’s heat, like a series of bent tubes. The tubes are then pumped up to a heat exchanger. A heat exchanger is the same device that is underground, except in reverse. In the heat exchanger, cold air is blown over a grid of hot, water-filled tubes. As the air moves past, it becomes warmer and the water becomes colder. To heat your home, all you need to do then is turn on a fan. To heat your water, you just have the pipe run through some water. You can get a dual-source heat pump that will handle both water and air heating with a single set of tubes. [1] [3]
These heat pumps work because the bottom ends of the tube are buried at a level where the ground is a constant 55 degrees Celsius. At this level, the ground is not subject to a fluctuation in temperatures that is seen at higher levels. As such, you will get the same temperature of water year-round, every year, for nearly no energy.
Where Can a Geothermal Heat Pump be Installed?
There aren’t really any geographic restrictions on where geothermal heat pumps can be installed. In areas where there is magma near the surface (i.e. Yellowstone or anywhere with plenty of hot springs) you can usually get away with far less tubing and a far shallower hole, meaning that the installation will be cheaper. And in areas where there is lots of seismic activity, you will want to consult with an expert before putting down your money. Otherwise, you could lose your investment to a shift in the earth. Beyond that, you can put a heat pump of this type pretty much anywhere, even the South Pole, if you are on land. [4] If necessary, the heating coils can even be laid horizontal.
How Much Do They Cost?
Geothermal heat pumps are expensive. If you are lucky, they cost three time as much as a comparable air and water heater. However, since you don’t have to pay much for electricity to power it, they tend to pay for themselves in 5-10 years. In addition, they are seen as an upscale addition, so your home’s value will likely rise. Another pro is that a geothermal heat pump can be expected to last 25-plus years for the components in your house and 50-plus for the loop in the ground. If you can afford the premium, geothermal heat pumps may be good deal for you. [2]
Sources:
1. http://www.consumerenergycenter.org/home/heating_cooling/geothermal.html
2. http://www.geothermalgenius.org/how-it-works.html
3. http://www.energysavers.gov/your_home/space_heating_cooling/index.cfm/mytopic=12640
4. http://en.wikipedia.org/wiki/geothermal_heat_pump
