What Lies Beneath: Ground Source Heat

Held just below the earth’s surface is a huge energy storage device, capable of absorbing 47% of the sun’s energy—that’s more than 500 times the energy mankind needs every year in a clean, renewable form.  GeoExchange systems, also known as geothermal heat pumps or ground source heat technology, take advantage of this great reservoir, transferring a home’s or business’ heat from one place to another using a simple process to provide both heating and cooling.

closed loop GeoExchange system uses the earth as the heat transfer medium, employing antifreeze pumped through a continuous loop of sealed polyethylene pipes buried beneath the ground vertically or horizontally.  In contrast, open loop systems draw water directly from a well, lake, or pond and pump it through a heat exchanger at the geothermal heat pump, after which the water is returned to its source.

In winter, GeoExchange systems bring the earth’s warmth up to a building and then transfer it into each room or zone via a heat pump.  In summer, they work in reverse to provide air conditioning, absorbing heat from inside a building and dissipating it to the cooler earth below.

Sara Quinn is the communications director for the Geothermal Heat Pump Consortium (GHPC), a partnership of national organizations and other groups working to increase awareness of GeoExchange technology.  Despite the challenge of public awareness, Quinn states that the average growth rate of installations has exceeded 20 percent during the last six years. “It’s a significant increase, even though we’re just a small part of the HVAC market.”

Quinn also says the term GeoExchange was adopted due to confusion between geothermal heat pumps and geothermal power.  “Power uses geysers, while pumps use the earth’s regular temperature,” she explains.  “Geothermal power generation is done mainly on the West Coast, whereas you can install a geothermal heat pump anywhere in the United States or the world.  Wherever you can drill a hole or trench, you can install the system.”

Steve Hoover, a Western Pennsylvania entrepreneur in the field, began equipping rural and suburban homes with geothermal heat pumps about seven years ago.  Currently, as vice president of technological services for GeoPower Systems, LLC, his company is involved only with businesses and community units (developments or densely populated homes) in urban areas.  GeoPower operates in a unique fashion. The business doesn’t charge any upfront installation fees (the systems’ biggest obstacle) and, instead, collects the monetary difference in energy savings between a guaranteed 10 percent, kept by the consumers, and the actual savings percentage, which ranges from 30-70 percent in heating mode to 20-50 percent in the cooling mode.

“By and large,” Hoover says, “geothermal is the most efficient way to heat and cool buildings, taking life-cycle costing—installation, maintenance, and replacement—into consideration.  Nothing comes closer.”

Maintaining the units, as documented by the U.S. Department of Labor, costs 40 percent less than traditional systems.  “The pipes are guaranteed for 50 years,” Hoover states, “and if anything goes wrong, it’s usually not a problem with the geothermal aspect of the system.”

“All you have to do is change a filter occasionally,” Quinn agrees, “and, since the unit is housed indoors in an attic or basement, there are no weatherization problems to worry about.  Also, no pollutants are emitted since there is no combustion process on-site.  Only a small amount of electricity is used to manipulate the heat pump.”

Doubting the ability of GeoExchange systems to ever be competitive on their own due to low volume production and high pricing, Hoover believes their real future lies in a partnership with other emerging technologies.  “We’re going to see a lot of geothermal combined with solar and fuel cells because of the way they complement each other.  People will be able to generate their own electricity through the cells, which in turn can operate the heat pumps.”

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