What is geothermal energy?

The literal translation for geothermal is “earth heat” from the words geo meaning earth and thermal meaning heat.

Just below the surface of the ground, the Earth maintains a stable temperature between 50° and 60°F (10°-16°C). This ground temperature is warmer than the air above it in the winter and cooler than the air in the summer. Geothermal heat pumps take advantage of this consistent temperature to heat and cool buildings.

What are geothermal heat pump systems?

Most geothermal heat pump systems are made up of three parts: the ground heat exchanger, the heat pump unit, and the air delivery system (ductwork).

The heat exchanger is a system of pipes called a loop; the pipes are buried approximately 10 feet below the surface in close proximity to the building that will be utilizing the geothermal energy.  Usually water (or a mixture of water and antifreeze) circulates through the “loop” to absorb heat from the ground in the winter or relinquish heat to the ground in the summer.

In the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system. In the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger. As an added benefit, the heat exchanger can transfer the indoor air during the summer to the hot water heating system, providing an inexpensive source of hot water.

Geothermal heat pumps use much less energy than conventional heating systems, since they draw heat from the ground. They are also more efficient when cooling your home. Not only does this save energy and money, it reduces air pollution and provides a “green” energy alternative.

If you are interested in learning more about geothermal energy or geothermal heat pump systems, see our April 2010 newsletter article titled “Groton residents harness geothermal energy” or visit the following web sites: