Geothermal energy is heat energy from the earth—Geo (earth) + thermal (heat).
Geothermal resources are reservoirs of hot water that exist or are human made at varying temperatures and depths below the Earth's surface. Wells, ranging from a few feet to several miles deep, can be drilled into underground reservoirs to tap steam and very hot water that can be brought to the surface for use in a variety of applications, including electricity generation, direct use, and heating and cooling. In the United States, most geothermal reservoirs are in the western states.
Benefits of Geothermal Energy
Renewable—The heat flowing from Earth’s interior is continually replenished by the decay of naturally occurring radioactive elements and will remain available for billions of years.
Baseload—Geothermal power plants produce electricity consistently and can run essentially 24 hours per day/7 days per week, regardless of weather conditions.
Domestic—U.S. geothermal resources can be harnessed for power production without importing fuel.
Small footprint—Geothermal power plants are compact. They use less land per gigawatt-hour (404 m2) than comparable-capacity coal (3,642 m2), wind (1,335 m2), and solar photovoltaic (PV) power stations (3,237 m2)*.
Clean—Modern closed-loop geothermal power plants emit no greenhouse gasses and have life cycle emissions four times lower than solar PV, and six to 20 times lower than natural gas. Geothermal power plants consume less water on average over the lifetime energy output than most conventional electricity-generation technologies**.
U.S. Geothermal Growth Potential
The 2019 GeoVision analysis indicates potential for up to 60 gigawatts of electricity-generating capacity, more than 17,000 district heating systems, and up to 28 million geothermal heat pumps by 2050. If we realize those maximum projections across sectors, it would be the emissions reduction equivalent of taking 26 million cars off U.S. roads every year.
U.S. Department of Energy Geothermal Technologies Office
The U.S. Department of Energy (DOE) Geothermal Technologies Office (GTO) focuses on realizing the potential to generate electricity and produce heating and cooling for U.S. homes from clean, domestic geothermal resources. To do so, GTO works in partnership with industry, academia, the DOE's national laboratories, and others on research, development, and demonstration activities focused on these areas:
What Does GTO Do?
- GTO receives taxpayer money, appropriated to GTO by Congress ($110M in 2021).
- To ensure money is released the right way, GTO reaches out to diverse stakeholders for strategic direction and planning (typically public/private companies, municipalities, universities, and national laboratories).
- GTO makes these plans available to the public.
- GTO offers the public opportunities to receive funding for geothermal projects. Entities apply, and after a GTO review and negotiation, GTO selects projects and releases funding to those entities. These projects may perform research, development, and demonstration activities that will drive more geothermal use.
- GTO then monitors how the entities spend those funds.
- Finally, GTO releases public data and reports, and hosts events showcasing the projects’ results and progress for broad accessibility.
The federal government invests in geothermal because it supplies clean, renewable power around the clock, emits little or no greenhouse gases, and takes a very small environmental footprint to develop. It also offers a low-carbon way to heat and cool buildings.
*Geothermal Energy Administration. A Guide to Geothermal and the Environment. 2007.
**Argonne National Laboratory. Life Cycle Analysis Results of Geothermal Systems in Comparison to Other Power Systems; Figure 16, page 43. August 2010.
Argonne National Laboratory. Water Use in the Development and Operation of Geothermal Power Plants; Table 4-3, page 26. January 2011.
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