Environmental Impacts of Geothermal Energy

The document details the environmental footprint of geothermal power, distinguishing between hydrothermal and enhanced geothermal systems. It highlights that while closed-loop systems minimize air emissions and water contamination, open-loop systems release gases like hydrogen sulfide and carbon dioxide. The text notes that geothermal energy has significantly lower life-cycle global warming emissions than coal or natural gas, though it can be associated with land subsidence and increased earthquake frequency.

• Geothermal plants impact water quality and consumption, though most U.S. facilities use closed-loop systems to prevent contamination, and there are no reported cases of water contamination from geothermal sites in the United States. Water requirements for cooling range from 1,700 to 4,000 gallons per megawatt-hour, but the use of geothermal fluids instead of freshwater can reduce the overall impact.
• Air emissions vary by system type: closed-loop systems have minimal emissions, whereas open-loop systems emit hydrogen sulfide, carbon dioxide, ammonia, methane, and boron. Hydrogen sulfide converts to sulfur dioxide, which can cause heart and lung disease and acid rain, although geothermal SO2 emissions are approximately 30 times lower per megawatt-hour than those from coal plants.
• Geothermal energy production can lead to land subsidence due to water removal from reservoirs and an increase in earthquake frequency, particularly with hydrothermal plants and enhanced geothermal systems (hot dry rock) that use high-pressure water to fracture rock.
• Life-cycle global warming emissions for geothermal energy are significantly lower than for fossil fuels. Open-loop systems emit approximately 0.1 pounds of carbon dioxide equivalent per kilowatt-hour, and enhanced geothermal systems emit approximately 0.2 pounds, compared to 0.6 to 2 pounds for natural gas and 1.4 to 3.6 pounds for coal.

APA

Union of Concerned Scientists (2013). Environmental Impacts of Geothermal Energy. https://www.ucs.org/resources/environmental-impacts-geothermal-energy

Chicago

Union of Concerned Scientists. Environmental Impacts of Geothermal Energy. 2013. https://www.ucs.org/resources/environmental-impacts-geothermal-energy.

Wikipedia

{{cite report |author=Union of Concerned Scientists |title=Environmental Impacts of Geothermal Energy |date=5 March 2013 |url=https://www.ucs.org/resources/environmental-impacts-geothermal-energy |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{unionofconcernedscientists2013environmental, author = {{Union of Concerned Scientists}}, title = {{Environmental Impacts of Geothermal Energy}}, institution = {Union of Concerned Scientists}, year = {2013}, month = mar, url = {https://www.ucs.org/resources/environmental-impacts-geothermal-energy}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }