Some Geothermal Terms Defined

Ok, so you’ve heard about geothermal – but you’re not really sure what it is or how it actually works.  There is a lot of information out there about geothermal energy – on a large scale (as in power plants) and on a smaller scale (as in residential) – and some of it is downright confusing.  Below are some terms and diagrams that may help clear up some of the questions you have – and hopefully aid you in making an informed decision about your heating and cooling needs.

There is a lot of talk about GWH and MWe in geothermal discussions – break it down like this:


GWh – gigawatt hour thermal. A unit of heat energy for non-electrical uses equal to 1000 megawatt hours (MWh).

A GWh can heat 860 thousand tons of water one degree centigrade (or bring about 9 million quarts of freezing water to a boil).

MWe – megawatt electrical. A unit of electrical power equal to 1000 kilowatts (kWe) – enough (in the U.S) for about 1000 people.


A Ground Source Heat Pump system can be installed in a residential structure of any size, anywhere, whether it is single-family or multi-family. GSHPs can be installed on almost any size lot: under lawns, landscaped areas, driveways, or the house itself. An existing house can be retrofitted with a GSHP using the ductwork that is already there. We will be able to determine any ductwrok issues or requirements you may have and whether any modifications are required. 

The Department of Energy (DOE) and the Environmental Protection Agency (EPA) have both endorsed ground source heat pump systems as among the most energy efficient and environmentally friendly heating, cooling, and water heating systems available. In a 1993 report, the EPA concluded that geothermal technologies represent a major opportunity for reducing national energy use and pollution, while delivering comfort, reliability and savings to homeowners.

The diagrams below show how geothermal work:

In the winter:

geothermal in winter 

And in the summer:


Ground Source Heat Pumps offer great benefits:


  • Can be a combination heating/cooling and hot water heating system
  • Made of mechanical components that are either buried in the ground or located inside the home
  • About the same size as a traditional heating/cooling unit
  • Can cut energy consumption by 20 to 50% and reduce maintenance costs
  • Keep the air warmer in the winter (90 -105 F) and at a more consistent temperature throughout the home, eliminating the hot and cold spots common with other systems
  • Very quiet, providing a pleasant environment inside & outside the home
  • No noisy fan units to disturb outdoor activities
  • No exposed equipment outdoors; children or pets cannot injure themselves or damage exterior units
  • No open flame, flammable fuel or potentially dangerous fuel storage tanks


This entry was posted on Friday, June 29th, 2012 at 3:41 pm. Both comments and pings are currently closed.

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