Whether the energy is harnessed for larger power plants or to heat and cool your home, the process of obtaining geothermal energy is basically the same. The energy gained in this process is via the heat produced by the internal temperature of the earth. If you drill or dig far enough down into the earth's crust you encounter layers of the earth that stay at a constant temperature year round (typically around 55 degrees Fahrenheit).
In terms of a geothermal heating and cooling system, pipes are laid in ditches that snake either vertically or horizontally. The pipes are then connected to the main portion of the system. After the pipes are covered back over with soil and the rest of the system is readied, a partly-water solution is added to circulate through the piping.
In the winter, the warm earth heats the pipes and the solution inside them. The liquid travels to the main portion of the system and the heat captured underground is transferred to produce warm air to heat the house. In the summer, the system works in reverse: the air intake collects the warm air which transfers to the liquid in the pipes. Once underground, the heat radiates into the surrounding soil and the cooled solution travels back around to release cool air into the house.
Benefits of Geothermal:
Almost no CO2 emissions.
Small surface footprint.
Available almost everywhere.
Facts on Geothermal:
UN World Energy Assessment reported that the geothermal resources are about 280,000 times the amount of primary energy consumed globally on a yearly basis.
(José Goldemberg (ed.), “Chapter 5: Energy Resources,” World Energy Assessment: Energy and the Challenge of Sustainability (New York: United Nations Development Programme, 2000)
The energy available roughly two miles underground is enough to supply about 30,000 years of energy in the US at the current rate of consumption.
(Bruce D. Green and R. Gerald Nix, “Geothermal‚ The Energy Under Our Feet: Geothermal Resource Estimates for the United States,” Technical Report (National Renewable Energy Laboratory: NREL/TP-840-40665, November 2006)
An MIT assessment in 2006 stated that the “extractable portion” of domestic geothermal energy is “about 2,000 times the annual consumption of primary energy in the United States.”
(Jefferson W. Tester, Brian J. Anderson, Anthony Stephen Batchelor, David D. Blackwell, Ronald DiPippo, Elisabeth M. Drake, John Garnish, et al., The Future of Geothermal Energy: Impact of Enhanced Geothermal Systems (EGS) on the United States in the 21st Century (Massachusetts Institute of Technology, 2006)
US Secretary of Energy Steven Chu has positioned that the amount of available geothermal energy is “effectively unlimited.”
(Google.org, “Enhanced Geothermal Systems (EGS)” video clip. Available at: http://www.youtube.com/)?v=O6r_3AgI49Y.)