Inside the earth is a large heat source that can be used for geothermal energy. Evidence of this heat and energy is steam or lava that comes out of volcanoes. In locations where this heat source is close to the earth’s surface, it can be used for electric power generation.
Another form of geothermal energy is the low-temperature geothermal energy due to the average ambient temperature at that location. This energy is available to everyone with a heat pump system that utilizes the ground temperature just below the surface which remains around 50 to 60 degrees (F) all year.
A geothermal heat pump utilizes the constant temperature of the ground to bring heat into the home during the winter and get rid of heat to the ground in the summer. The system has pipes that are buried under the ground in a vertical or horizontal manner to create a loop for water to flow. The water is circulated with a pump, and a heat exchanger inside the house transfers heat between the inside air and water in the loop.
Because the ground temperature is nearly constant all year, the heat pump can provide both heating in the winter and cooling in the summer from the same system. Although the system will need an extra source of energy for extremely hot or cold days, it can provide a large fraction of the heating and cooling at little cost while creating no pollution.
The N.C. Solar Center uses a geothermal heat pump to provide heating and cooling to the NCSU Solar House.