How Geothermal Energy Works

The document describes geothermal energy as a sustainable, baseload power source derived from Earth's internal heat. It details three types of power plants—dry steam, flash, and binary cycle—and the use of ground-source heat pumps for building climate control. While the U.S. is a global leader in capacity, largely centered in California, the text highlights emerging technologies like Enhanced Geothermal Systems (EGS) and co-production in oil and gas wells as keys to unlocking vast untapped energy reserves.

• Geothermal energy provides a consistent source of baseload electricity with capacity factors comparable to nuclear and coal power, making it a stable alternative to variable renewables like wind and solar.
• The United States is a global leader in geothermal capacity, with over 3,300 MW installed across eight states; California alone hosts more than 40 plants that generate nearly 7 percent of the state's electricity.
• There are three primary geothermal power plant designs: dry steam (direct steam use), flash (depressurizing hot water into steam), and binary cycle (using a heat exchanger and a secondary liquid like isobutane). Binary systems offer the most growth potential because they can utilize lower-temperature water resources.
• Ground-source heat pumps utilize the constant underground temperature of approximately 50°F to heat and cool buildings. These systems are highly efficient, circulating 3 to 5 times the energy they consume, though high upfront costs and installation difficulties remain barriers to wider adoption.
• Enhanced Geothermal Systems (EGS), or "hot dry rock" technology, involve fracturing deep rock reservoirs with high-pressure water to create circulation. An MIT study suggests EGS could provide 100 gigawatts of electricity by 2050, though the technology carries a low risk of induced seismic activity.
• Co-producing geothermal electricity from existing oil and gas wells could utilize the 25 billion barrels of hot water produced annually in the U.S. to generate up to 3 gigawatts of baseload energy.

APA

Union of Concerned Scientists (2008). How Geothermal Energy Works. https://www.ucs.org/resources/how-geothermal-energy-works

Chicago

Union of Concerned Scientists. How Geothermal Energy Works. 2008. https://www.ucs.org/resources/how-geothermal-energy-works.

Wikipedia

{{cite report |author=Union of Concerned Scientists |title=How Geothermal Energy Works |date=14 July 2008 |url=https://www.ucs.org/resources/how-geothermal-energy-works |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{unionofconcernedscientists2008how, author = {{Union of Concerned Scientists}}, title = {{How Geothermal Energy Works}}, institution = {Union of Concerned Scientists}, year = {2008}, month = jul, url = {https://www.ucs.org/resources/how-geothermal-energy-works}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }