Do you know the difference between "geothermal energy" and a "ground source heat pump"? All I know is they both run into the ground. But as this article from Green Building Elements explains how together they can more efficiently heat and cool your home at a dramatically reduced price.
Simply stated, a geothermal energy system uses heat from below the surface of the Earth as an energy source (think: tapping into a geyser or a volcano for power).
A "ground source heat pump," also known as a "geoexchange system," uses the ground's stable year-round temperature to more efficiently heat or cool your home. How it does this is best explained by this video. Interested? Do a search on this site to find qualified geoexchange contractors in your area.