John Ballman of Aurora, Colorado shows off his geothermal heat pump, which both warms and cools his home.© Warren Gretz/NREL
Hooray for Heat Pumps
A geothermal heat pump is an environmentally friendly device homeowners can use to siphon heat from the Earth’s surface to use for heating, air conditioning and hot water. Unlike conventional furnaces that must burn fuel—usually natural gas, propane or oil—geothermal heat pumps simply take advantage of the Earth’s natural heat. Typically, water is cycled through an underground pipe, and the heat in the surrounding soil warms or cools the heat pump’s refrigerant. Hot and cool air is then distributed through a home by electrically driven compressors and heat exchangers that employ the same principles as a refrigerator.
"It’s a truly renewable system using heat from the Earth’s surface and requiring a minimal amount of energy to deliver that heat," explains Lisa McArthur, a representative of the International Ground Source Heat Pump Association, a trade group. "The temperature underground is constant [low 40s in the northern U.S. to the low 70s in the South]. If a home needs to be heated in the winter or cooled in the summer, the energy source is in one’s own backyard," she says.
McArthur, who has owned her own heat pump for about a year, says, "It’s a quiet system and I am completely unaware it’s there. The air quality is also better, and so are my allergies."Depending upon the size and quantity of heat pumps, a homeowner may expect to pay a few thousand dollars more for installation than for a conventional fossil-fuel system. But with geothermal, homeowners enjoy reduced energy bills, high reliability and long life.
Clark pays roughly $125 per month to heat or cool his 5,200 square feet. As for McArthur, her new 1,600-square-foot home is the same size as her old one but costs half as much to heat and cool. "It is constantly comfortable throughout, with no hot or cold spots," she adds.
According to the U.S. Department of Energy, geothermal technology can reduce energy costs 30 to 60 percent compared to traditional furnaces. This means a geothermal unit will pay for itself in two to 10 years. Subsidies and tax incentives, which vary from state to state, can make the systems even more affordable.
"There is always initial sticker shock, but our clientele is more concerned with the environment and long-term use rather than the initial bottom line," says Scott Jones, a sales manager at ECONAR, a Minnesota-based heat pump producer. According to Jones, experienced homeowners building or buying their third or fourth (and often last) home are often more open to considering the technology, since they know they are getting a long-term investment. "For every dollar put into the building and maintenance of heat pumps, there is $3.50 of output," adds Jones.
Geothermal Goes Global
For many years, people in volcanically active places such as Iceland and New Zealand have taken advantage of the intense local geothermal heat to warm their homes and even produce electricity (by producing steam as water is pumped over the hot rocks). As a result, Iceland, for example, has largely been able to avoid the use of fossil fuels and boasts some of the purest air and water on Earth. However, the caveat of such renewable technology was always thought to be its limited geographic distribution.
But with advances in heat pump technology, geothermal energy is poised for widespread service beyond the denizens of Reykjavik. Experts say geothermal heat pumps can be used almost anywhere in the U.S. and the world.
Former oilman President George W. Bush installed a geothermal heat pump at his Texas ranch during the 2000 election campaign. The word in the industry is that Vice President Dick Cheney will soon be installing a heat pump at his private estate.
Large-scale geothermal power plants, which emit little carbon dioxide, no nitrogen oxides, and very low amounts of sulfur dioxide, are also feasible. The geothermal industry and the U.S. Department of Energy are developing technologies to recycle minerals contained in geothermal fluid so that little or no disposal or emissions occurs.
Supporters say that increased geothermal energy production could reduce dependence on foreign oil and help stem the flow of toxic emissions. One of our critical energy options, they say, may be just beneath our feet.
JESSICA WORDEN looks forward to installing a geothermal heat pump in her home.