Geothermal

A geothermal plant in Iceland.

The geothermal process is based on a simple premise: Below the frost line — usually about four feet deep — the earth is a constant temperature of about 50 degrees Fahrenheit all year long. During the winter, the heat pump absorbs heat from the ground and uses it to warm the air in your home. In the warmer summer months, the process is reversed, taking heat from your home and transferring it back into the ground.

The basic elements of a geothermal system include: underground loops of plastic piping, a liquid antifreeze system, a heat pump, and an air distribution system.