Geothermal heat pumps are electrically powered systems that use the earth’s relatively constant temperature to provide heating, cooling, and hot water. In heating mode, GHPs extract heat from the earth and distribute it to the home or building, typically through a system of air ducts. In cooling mode, the process reverses: the GHP absorbs heat from the home or building and transfers it to the ground.
GHPs have been around since the 1940s, before solar and wind power. In fact, in 1948, J.D. Krocker, an engineer from Portland, pioneered the first commercial building use of a groundwater heat pump. With significant improvements in installation methods, materials used, electronic control systems, and efficiency, GHPs have increased in popularity somewhat. While they offer extensive environmental benefits and are cost effective and easy to maintain, they still aren’t receiving as much attention as the solar and wind energy markets.
“The state of Oregon has gone on a solar bandwagon,” Al Stephens, owner of Stephens Heating and Air Conditioning in Corvallis, said.
Stephens Heating has been working with GHPs since 1981 and is one of only a handful of companies in the immediate area that installs them.
GHPs are available with efficiencies of 50 to 70 percent — higher than other heating systems – and 20 to 40 percent higher than available air conditioners. In addition to efficiency gains, GHPs also make environmental sense. The U.S. Department of Energy reports that nearly 40 percent of all U.S. emissions of carbon dioxide are the result of using energy to heat, cool, and provide hot water for buildings.
According to the Geothermal Heat Pump Consortium, a typical 3-ton residential GHP produces an average of one pound less CO2 per hour than a conventional system. To put that in perspective, over a 20-year lifespan, 100,000 units of nominally sized residential geothermal systems will reduce greenhouse gas emissions by almost 1.1 million metric tons. That would be the same as converting 58,700 cars to zero-emission vehicles, or planting more than 120,000 acres of trees.
Curt Sommer, a renewable energy consultant from West Linn, says that there “simply aren’t any drawbacks to GHPs.”
“Everything is designed to be as environmentally friendly as possible,” he said.
With more people learning about and understanding the technology, the Oregon Institute of Technology’s Geo-heat Center says that the use of GHPs has been increasing by approximately 20 percent per year.
“The lack of awareness has kept the GHP business small,” Stephens said. “A lot of people are scared of it, they think it’s way too high-tech.”
Cost is a factor that has deterred some people from choosing GHPs. Installing a geothermal system can cost a few thousand dollars more than a conventional system, but GHPs can pay off through reduced utility bills and upkeep costs.
The International Ground Source Heat Pump Association notes that GHPs can even result in a positive cash flow because unlike solar or wind systems, energy savings from GHPs usually exceed the cost of the system. The waste heat removed from the home’s interior during the cooling season can be used to provide virtually free hot water.
“One of the hurdles we have to overcome is that most of the homes being built now people plan to live in for 2-5 years, so they don’t plan to live in the house long enough to recoup their investment in geothermal,” Stephens said.
Sommer has encouraged the Energy Trust of Oregon to consider getting more involved with incentives for GHPs. Currently, Energy Trust’s renewable power incentives are available only for projects that use geothermal hot water or steam to generate electricity. Those interested in installing GHPs may qualify for an incentive from Energy Trust’s Home Energy Solutions program, but these incentives are substantially less than the incentives offered through the Renewable Energy Program.
“It would help if the Energy Trust would jump on board,” Stephens said.