Geothermal heat pumps: Using dirt to save money

Sisters area residents can use the earth to save up to 60 percent on heating and cooling costs - and be paid to do it.

Geothermal power generation is coming to Sisters. It is merely a matter of time. However, it is not necessary for folks to wait to be green and save energy by using the ground beneath our feet. Geothermal Heat Pump (GHP) technology is available today, and the State of Oregon and the U.S. Government will help to pay for it. Central Electric Cooperative will even loan area residents the money for its purchase and installation.

Although Sisters experiences seasonal temperature extremes, the ground remains at a relatively constant temperature only a few feet below the earth's surface. Like in a cave, this ground temperature is warmer than the air above it during the winter and cooler than the air in the summer.

GHPs take advantage of this by transferring heat stored in the earth into a building during the winter and transferring it out of the building and back into the ground during the summer.

GHPs, also known as a ground source heat pumps, are a highly efficient renewable energy technology that can provide heating and cooling for both homes and businesses. GHPs use the constant temperature of the earth as the exchange medium instead of the outside air as do conventional heat pumps. This allows GHPs to reach the high efficiencies of 400-600 percent on the coldest of winter nights compared to only 175-250 percent for conventional air-source heat pumps.

In addition to heating and cooling, GHPs can be used to provide hot water when the system is operating. Most residential systems are now equipped with desuperheaters that transfer excess heat from the GHP's compressor to the home's hot water tank in the form of superheated steam. Unfortunately, during the spring and fall when GHPs are generally not operating, the desuperheater cannot provide hot water.

However, because GHPs are so much more efficient than any other means of water heating, most manufacturers are beginning to offer "full demand" systems that use a separate heat exchanger built into the system to meet all of the household hot water needs throughout the year. These units can provide hot water as quickly and less expensively than any competing system, including the latest gas technologies.

GHPs are a well established technology and have been in use since the late 1940s. Approximately 40,000 GHPs are installed throughout the United States each year.

Since they work by concentrating the naturally existing heat of the earth, rather than by producing heat through combustion of fossil fuels, they are very environmentally friendly. From the estimated one million GHP installations that exist in the United States today, more than 5.8 million metric tons of CO2 emissions are eliminated annually. The U.S. Environmental Protection Agency estimates that these million units have had the same effect as removing nearly 1.3 million cars from the road and have reduced U.S. reliance on imported fuel by 21.5 million barrels of crude oil per year.

According to the same agency, the typical electric expense for a 2,000-square-foot home equipped with a GHP is about $1 per day.

The State of Oregon provides a Residential Energy Tax Credit for residents, including both homeowners and renters, if they purchase a closed-loop GHP.

The system can also include water heating with the desuperheater option and still qualify.

Through the installation of a GHP, taxpayers are eligible for a credit of $0.60 per kWh saved during the first year, up to a maximum of $1,500.

The federal government also provides a somewhat less generous Personal Tax Credit for the installation of a GHP. Currently the tax credit is $500; however, there is a new bill in Congress that could raise this amount significantly.

The price of a GHP is more than an air-source system of the same heating and cooling capacity. In the Sisters area, the additional costs are estimated to be recovered in energy savings over approximately five years. The GHP system's life is estimated at 25 years for the interior components and more than 50 years for the buried ground loop.

The additional cost frightens many potential buyers away from the the purchase of a GHP even though the system will literally pay for itself in energy savings and is much longer lasting than any conventional technology.

Central Electric Cooperative is ready to assist clients in the purchase through the Residential Energy Efficiency Loan Program. Qualifying customers are eligible for unsecured loans for 100 percent of the job cost up to $5,000.