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Geothermal Heat Pumps

Daniel Boone High School
Daniel Boone High saved $33,000 in energy costs the first year it had the geothermal heat pump.

Even if you’re not sure what “geothermal” means you can probably figure it out. Here are a couple of clues: “Geo” is in “geography” and “geology” so you know it has something to do with the earth. “Thermal” is like the underwear your parents make you wear when you go winter camping or snow skiing, so you know it keeps things warm.

Put the two together and here is what you get: Geothermal heat pumps use the earth to warm buildings in the winter and keep them cool in the summer. They work so well TVA helps Valley businesses and school systems install them in their buildings.

But wait a second—how can the earth heat things up or cool them down? Good question. Although the surface of the earth freezes in the winter and warms in the summer, the ground below the surface (under the frost line) stays a constant 57 degrees Fahrenheit.

A geothermal system taps into this climate-controlled world by pumping water through underground pipes. Here’s how it works:

  • During the winter, the water in the pipes absorbs warmth from the earth and heat pumps transfer it to the rooms in the building above.
  • During the summer, the reverse happens. Water is pumped down from the hot building where it is cooled underground. When it is pumped back up, the heat pumps transfer heat from the rooms into the cool water.

Why go geothermal?

diagram showing geothermal pipes buried in the ground
Water pumped through pipes buried in the earth carries heat back to the school in the winter and carries it away in the summer.

First of all, geothermal is good for the environment. The warmth of the earth is an inexhaustible source of energy. Other systems use non-renewable fossil fuels. Also, geothermal heat pumps use less electricity and the underground pipes are filled with tap water. That means no chemicals are in the system and nothing harmful can leak out.

Need some more reasons? Here you go:

  • Geothermal systems are quieter, more reliable, more efficient, and more compact compared to regular heating and cooling systems.
  • Owners of buildings using geothermal have cut 25 to 50 percent off their utility bills.
  • No cooling towers, rooftop units, or individual room air conditioning units are needed, so buildings and schools using geothermal systems look better.
  • There’s no fire hazard and no outside equipment that could potentially hurt kids