Find answers to our most frequently asked questions and learn more about the use of geothermal energy.
1. What is geothermal energy and how does it work?
Wells can be drilled into the earth to tap this energy. In the form of naturally occurring steam and hot water, geothermal energy can be drawn to the surface to generate electricity, heat and cool buildings, and serve other uses.
2. What are the benefits of using geothermal energy?
Several attributes make geothermal a beneficial source of energy, including:
- It's clean, offering energy that can be extracted without burning fossil fuels such as coal, gas, or oil. Using geothermal for electricity produces only about one-sixth of the carbon dioxide of a natural gas power plant, and little—if any—nitrous oxide or sulfur dioxide. Binary-cycle geothermal plants, which operate in a closed cycle, release essentially zero emissions.
- Geothermal power is “homegrown,” offering a domestic source of reliable, renewable energy.
- Geothermal energy is available 24 hours a day, 365 days a year, regardless of weather. Geothermal power plants have a high-capacity factor—typically 90% or higher—meaning that they can operate at maximum capacity nearly all the time. These factors mean that geothermal can balance intermittent sources of energy like wind and solar, making it a critical part of the national renewable energy mix.
- Geothermal energy can also be used to heat and cool homes and businesses, either with geothermal heat pumps or through direct use.
Learn more on our Geothermal Basics page and check out our GeoVision analysis.
3. Why is geothermal energy a renewable resource?
- Geothermal energy is heat that flows continuously from the Earth’s interior to the surface—and has been doing so for about 4.5 billion years. The temperature at the center of the Earth is about the same as the surface of the sun (nearly 6,000°C, or about 10,800°F).
- This heat is continually replenished by the decay of naturally occurring radioactive elements beneath the subsurface and will remain available for billions of years, ensuring an essentially inexhaustible supply of energy.
Learn more on our Geothermal Basics page.
4. Where is geothermal energy available?
In the United States, conventional hydrothermal resources—natural reservoirs of steam or hot water—are available primarily in the western states, Alaska, and Hawaii. However, geothermal energy can be tapped almost anywhere with geothermal heat pumps and direct-use applications. Enhanced geothermal systems (EGS), which can produce power wherever there is hot rock, will be increasingly deployed as the technology is further developed. EGS will also help expand geothermal heating and cooling nationwide.
Learn more about the Geothermal Technologies Office's projects to advance geothermal technologies.
5. What are some environmental benefits of using geothermal energy?
Geothermal technologies offer many environmental benefits, including:
- Low emissions from electricity generation. Geothermal power plants largely release only excess steam, with most plants discharging no air or liquid. This makes geothermal power plants a clean source of electricity and an important contributor to the nation’s zero-carbon future. Reaching the levels of geothermal electricity deployment outlined in the GeoVision analysis could help the United States avoid greenhouse gas emissions equal to the annual emissions of 6 million cars.
- Critical materials. Some geothermal plants produce solid materials, or sludges, that require disposal in approved sites. Some of these solids are now being extracted for sale (zinc, silica, and sulfur, for example), making the resource even more valuable and environmentally friendly. In addition, lithium—a critical material—is present in high concentrations in some geothermal brines. Learning to cost effectively extract that lithium could provide the United States with a domestic source of this important material.
- Efficiency and reduced carbon emissions for heating and cooling. Geothermal energy offers U.S. homes and businesses low-carbon and energy-efficient heating and cooling options, such as geothermal heat pumps, which use the constant temperature of the Earth to regulate heat from buildings. Reaching the target number of installed geothermal heat pumps outlined in the GeoVision analysis could help the U.S. avoid greenhouse gas emissions equal to the annual emissions of 20 million cars.
- Comparably low water use. By 2050, geothermal energy could represent 8.5% of total U.S. electricity generation while being accountable for only 1.1% of power-sector water withdrawals. The majority of this growth could be supported using non-freshwater sources.
Learn more in the GeoVision analysis Supporting Task Force Report: Impacts.
6. What is the visual impact of geothermal technologies?
District heating systems and geothermal heat pumps can usually be integrated easily into communities, with almost no visual impact. Geothermal power plants tend to have a lower profile and smaller land footprint compared to many other energy-generation technologies, and they do not require fuel storage, transportation, or combustion.
Learn more in the GeoVision analysis.
7. Can we run out of geothermal energy?
Geothermal energy is heat that flows continuously from the Earth’s core to the surface—and has been doing so for about 4.5 billion years. This heat is continually replenished by the decay of naturally occurring radioactive elements in the Earth’s interior and will remain available for billions of years, ensuring an essentially inexhaustible supply of energy. Geothermal power plants operate by drawing fluid or steam from underground reservoirs, and these reservoirs have been demonstrated long term at geothermal plants such as Lardarello in Italy (1913), Wairakei in New Zealand (1958), and The Geysers in California (1960).
Some geothermal power plants have experienced pressure and production declines, but operators are finding solutions to maintain reservoir pressure. For instance, the city of Santa Rosa, California, pipes its treated wastewater to The Geysers geothermal field to be used as reinjection fluid, thereby prolonging the life of the reservoir while recycling the treated wastewater.
Learn more about U.S. geothermal history.
8. Is geothermal energy expensive?
Over the long-term, geothermal power offers a cost-effective means of achieving aggressive decarbonization pathways; in the short-term, however, developing geothermal systems carries significant up-front costs.
Geothermal heat pumps (GHPs), for example, are cost-effective, mature technologies that have been in existence for decades but remain a niche application, due to the costs of implementing ground heat-exchanger loops. Likewise, the costs of building a geothermal power plant are heavily weighted toward early expenses rather than fuel to keep them running. Geothermal energy’s high-capacity factor—its ability to produce electricity 90% of the time or more—means that costs can be recouped more quickly because there is very little downtime once a plant is operational. But exploration activities—from pre-drilling geotechnical studies through exploration, confirmation, and development drilling—have a collective impact on overall project costs and success.
Learn more about how GTO’s research, development, and demonstration is tackling this issue.
9. What are the different types of geothermal power plants?
There are three geothermal power plant technologies being used to convert hydrothermal fluids to electricity: dry steam, flash steam, and binary cycle. The type of conversion is selected during project development and depends on the state of the subsurface fluid (steam or water) and its temperature.
Learn more about power plant types and see illustrations of each on the Electricity Generation page.
10. What does it cost to develop a geothermal power plant?
Costs of a geothermal plant are heavily weighted toward early expenses, rather than fuel to keep them running. Exploration activities—pre-drilling geotechnical studies, exploration, confirmation, and development drilling—have a collective impact on overall project costs and success. Most geothermal power plants can run at greater than 90% availability (i.e., producing more than 90% of the time), which means that costs can be recouped more quickly. However, operators need to balance operations with costs and electricity prices. Running at 97% or 98% can increase maintenance costs, but higher-priced electricity justifies running the plant 98% of the time because the resulting higher maintenance costs will be recovered.
Learn more about power plant types on the Electricity Generation page.
11. What makes a site good for geothermal electric development?
Elements that indicate a site may be good for geothermal electricity development include hot subsurface geothermal fluid with low mineral and gas content, shallow aquifers for producing and reinjecting the fluid, a location eligible for permitting, proximity to existing transmission lines or load, and other characteristics. Geothermal fluid temperature should be at least 300°F/149°C, although plants can operate on fluid temperatures as low as 210°F/99°C.
Learn more about power plant types and see illustrations of each on the Electricity Generation page.
12. How do geothermal heat pumps work?
Geothermal heat pumps, or GHPs, use the constant temperature of the shallow Earth (40–70°F/4.5–21°C) to provide heating and cooling solutions for buildings wherever the ground can be cost-effectively accessed to depths below seasonal temperature variations. The thermal energy storage properties of the rocks and soils allow GHPs to act as a heat sink—absorbing excess heat during summer, when surface temperatures are relatively higher—and as a heat source during the winter, when surface temperatures are lower. This increases efficiency and reduces the energy consumption of heating and cooling for residential and commercial buildings.
Learn more about geothermal heat pumps.
13. What is an enhanced geothermal system (EGS)?
The presence of hot rocks, permeability, and fluid underground creates natural geothermal systems. Small underground pathways conduct fluids through the hot rocks, carrying energy in the form of heat through wells to the Earth’s surface when the conditions are just right. At the surface, that energy drives turbines and generates electricity.
Sometimes conditions are not perfect for natural geothermal systems; the rocks are hot, but they are not very permeable and contain little water. The injection of fluid into the hot rocks enhances the size and connectivity of fluid pathways by reopening fractures. Once created, an enhanced geothermal system (EGS) functions just as a natural geothermal system does. The fluids carry energy to the surface, driving turbines and generating electricity.
Learn about EGS, how it works, and its future in the United States.
14. How does geothermal district heating and cooling work?
District and community-scale geothermal heating and cooling systems use one or more underground loops to create a heating and cooling network that can use a series of heat pumps. New and different configurations of these systems are emerging in universities and communities all over the United States. GTO’s Community Geothermal Heating and Cooling Design and Deployment initiative is focused on supporting communities in implementing such systems and will grow the body of replicable case studies to increase deployment nationwide.
Learn more about community geothermal systems.
15. What are barriers to geothermal development in the United States?
Barriers to deploying geothermal resources are mainly a result of geothermal energy’s unique characteristics as a subsurface resource. Exploring, discovering, developing, and managing geothermal resources is inherently complex and can have greater risks and upfront costs than other renewable energy technologies. Geothermal can also face barriers in land access, permitting, and project financing. In addition, all geothermal resources share a key non-technical barrier: lack of awareness and acceptance. Resources like solar and wind are easy to see and feel, but—by its nature—geothermal energy is relatively unknown because it’s in the subsurface.
Learn more about barriers to geothermal deployment in section 2.4 of the GeoVision analysis and this report on non-technical barriers.
16. How is geothermal covered in the Bipartisan Infrastructure Law?
The 2021 Bipartisan Infrastructure Law includes $84 million for the Geothermal Technologies Office to stand up 4–7 enhanced geothermal system (EGS) pilot demonstration sites over the next four years. The new law focuses on projects that demonstrate EGS technology in different geologic and geographic settings—including one in the eastern portion of the United States—using a variety of techniques and well completions.
Learn more about the Bipartisan Infrastructure Law EGS pilot demonstration sites.
17. How is geothermal covered in the Inflation Reduction Act?
The Inflation Reduction Act (IRA) has numerous provisions that include geothermal. The IRA will lower costs for families, combat the climate crisis, reduce the deficit, and ask the largest corporations to pay a fair share. This includes lowering energy costs—saving families $500 per year on energy bills—and tackling the climate crisis as the most significant legislation in U.S. history to cut pollution, advance environmental justice, and improve American energy security.
The IRA extends the investment tax credit (ITC) and the production tax credit (PTC) for renewables, including geothermal, through 2024. It also provides a 30% tax credit, up to $2,000, for the purchase of a heat pump (geothermal or air source), as well as funding for states to offer rebates on household efficiency improvements.
Learn more about the Inflation Reduction Act by the Numbers and its impact in your state.
18. What kinds of research does the Geothermal Technologies Office do?
GTO works to reduce costs and risks associated with geothermal development by supporting innovative technologies that address key exploration and operational challenges. In partnership with industry, academia, and the Department of Energy’s national laboratories, GTO works on research and development activities in the following areas:
19. What are some current Geothermal Technologies Office initiatives?
GTO’s Geothermal Everywhere page is a great place to find the latest GTO initiatives. You can also sign up for the Drill Down monthly newsletter for updates about GTO’s initiatives, funding opportunities, and other news.
Learn more about GTO’s areas of research.
20. How does the Geothermal Technologies Office fund research?
GTO’s budget is set through congressional appropriations. Each year, GTO proposes a body of research to be pursued in the next fiscal year and the accompanying budget through what is called a Congressional Budget Justification, or CBJ. Congress reviews the information and sets a budget within the scope and confines of the overall federal fiscal year budget. CBJs are a matter of public record.
GTO organizes its portfolio to ensure we are investing in high-value and high-return research with real potential to expand geothermal deployment.
Learn more about what GTO does and how it funds projects.
21. How do I know which funding opportunity is right for me?
GTO offers a range of funding opportunities that help industry, academia, national laboratories, communities, and entrepreneurs research, develop, and demonstrate geothermal innovations. GTO creates Funding Notice webpages for each funding opportunity to help potential applicants understand the objectives, major requirements, and application timeline, as well as navigate the application process. Some opportunities also have shorter versions of that guidance, called Quick Guides, to help potential applicants understand the FOA and application requirements. For example, explore our Geothermal Energy from Oil and gas Demonstrated Engineering (GEODE) Funding Notice page and Quick Guide.
GTO’s website also includes a page dedicated to open funding opportunities, and the Office of Energy Efficiency and Renewable Energy (EERE)—of which GTO is a part—has a dedicated funding opportunities page as well. GTO also funds projects as part of the Small Business Innovation Research program, and several geothermal-related prizes under the American-Made Challenges program.
All funding opportunities and application details are accessible at the EERE Exchange portal.
To stay up to date on our latest funding opportunities and prizes, subscribe to the Drill Down newsletter and sign up for office updates.
22. What student opportunities are there in geothermal energy?
DOE participates in several initiatives designed to give students real-world experience in geothermal.
The Geothermal Collegiate Competition offers students the opportunity to compete for cash prizes, gain resume experience in the renewable energy industry, and engage with established industry professionals as well as their local communities.
The U.S. National Science Foundation (NSF) and DOE are partnering on an opportunity through NSF’s INTERN program that will support 10 to 20 six-month research internships per year to work in the geothermal industry on projects that advance geothermal technologies.
The Clean Energy Innovator Fellowship program, sponsored by GTO and seven other offices, funds recent graduates and energy professionals to work with energy organizations for up to two years to advance clean energy solutions and increase access to clean energy career opportunities across the country.
Other student programs GTO participates in include GEM fellowships, the Minority Serving Institutions Partnership Program internship program, and fellowships under the American Association for the Advancement of Science and the Presidential Management Fellows program.
Additionally, all GTO-funded projects are required to upload their data to the Geothermal Data Repository (GDR) for public use. Those data are complemented by Final Technical Reports that GTO researchers upload to OSTI.gov. Students are encouraged to access and use the GDR for research and educational purposes.
Learn more about student opportunities by signing up for the Drill Down newsletter.
23. How can I find someone to install a geothermal system at my home or business?
It’s great that you are interested in using geothermal in your home or business! There are a few ways you can research possible installers. A good place to start is on the Energy Saver Geothermal Heat Pump page, which describes the various types of systems and provides resources for organizations with databases of installers nationwide. You can also contact your state energy office or do an Internet search on “geothermal installers in my area” or similar terms; most installers have websites that explain their services and provide contact information. A qualified installer can also help you understand any incentives that might be available for the system(s) you are considering, or you can check the Database of State Incentives for Renewables and Efficiency.