Drill, Baby, Drill
While politicians have been arguing over drilling in the Arctic and along the coasts, an “underground” energy movement has been quietly taking shape. Last August, Google’s philanthropic group Google.org announced it was investing over 10 million dollars in an energy technology called Enhanced Geothermal Systems (EGS). Google’s initiative, called RE<C, is working to develop electricity from a renewable source that is cheaper than coal.
Geothermal’s selling point is that it can deliver vast quantities of power at all times: There’s no waiting for the wind to blow or sun to shine. And, it can be captured almost anywhere on the planet. EGS involves drilling a well miles into the earth’s hot crust and circulating a fluid through pipes back to the surface where the hot water and steam then power a turbine that creates electricity. The world’s first commercial EGS plant is underway in Australia.
The Home Version
While we’re waiting for enhanced geothermal to show up in large-scale energy production in America, the home version is well underway. About six million people in the U.S. get energy from geothermal applications—nearly half from geothermal plants in the West, and the other half from direct-use and geothermal heat pumps. Also known as ground-source heat pumps (GSHPs), geothermal heat pumps use a similar concept as an EGS plant, only on a much smaller scale. Because the upper 10 feet of the earth maintains an almost constant temperature between 50° and 60°F (10°-16°C), the pumps exchange air with the ground to heat and cool buildings.
During installation, 200-300-foot holes are drilled into the yard and pipes are inserted vertically, or pipe is laid out horizontally about six feet under the ground. Water is circulated through the pipes, and is exchanged in a heat pump about the size of a medium refrigerator inside the house.
Though the initial cost of installation is sometimes two to three times greater than that of an electric heat pump, the savings in electricity brings a payback of three to eight years (two to three years for commercial buildings). Thereafter, homeowners will enjoy a 25%-65% reduction in heating and cooling electricity costs for the life of the system—about 25 years for the unit and 50 years for the ground loop. There is a positive cash flow, since the energy savings usually exceed payment on the system, according to the International Ground Source Heat Pump Association (IGSHP).
Demand Is Growing
Ground-source heat pumps only use electricity to move heat, not produce it, so a GSHP typically supplies four to five kilowatts of heat for every kilowatt of electricity used. Three to four of these kilowatts of heat come directly from the earth itself, and are clean, free and renewable. According to the IGSHP, these heat pumps also minimize ozone layer destruction by using factory-sealed refrigeration systems, which will seldom if ever have to be recharged. And because the system doesn’t rely on outside air, it keeps a home’s inside air cleaner and free from pollens, outdoor pollutants, mold spores and other allergens.
Demand for GSHPs is increasing at a rate of about 20% per year, according to the Geo-Heat Center at the Oregon Institute of Technology. That kind of growth is about all the industry can handle for now: A recent New York Times article brought to light the struggle the industry is having in keeping up with demand for the machinery, contractors, drillers and other trained workers.
For Houses Old and New
A GSHP makes sense for a new home, since the cost of the heat pump is figured into the mortgage. Homeowners who are planning to retrofit their homes with renewable energy often first think of solar, but a GSHP may be a better first choice, says Brian Henderson of Envinity, Inc., a green design and construction company in State College, Pennsylvania. GSHPs can take care of about half of the hot water needs of a household, as well as dehumidifying the home, so once the GSHP is up and running (which it does very quietly), it’s easier to get an idea of how much solar would be needed to take care of the rest of the electric load.
According to the U.S. Department of Energy, about 64% of a home’s energy consumption is for heating, cooling and hot water. A GSHP might just be the answer to the vital need to conserve that energy, and give new meaning to the cry of “Drill, baby, drill.”