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.