Geothermal Energy
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Fast Facts About
Geothermal Energy
Principal Energy Uses: Heat, Electricity
Form of Energy: Thermal
Geothermal energy makes use of abundant natural heat deep below the Earth’s surface. Geothermal resources are accessible where the Earth’s crust is thin or faulted or near volcanic activity, which often occurs near tectonic plate boundaries.
Geothermal has two main uses:
- Direct Use Heat: High-temperature water or steam is used to provide heat for buildings, agriculture, aquaculture, industrial processes, and recreation (e.g., hot springs)
- Electricity: High-temperature water or steam is used to run a steam cycle power plant and generate electricity
There are three things needed in a traditional geothermal resource–permeability, heat, and water. Finding these conditions requires significant up-front capital expenditures. The exploration begins with geophysical assessments but eventually actual drilling and testing must be done to ensure that these conditions are present. These similarities with the oil and gas exploration process enable the transfer of knowledge, technology, and jobs from the fossil fuel industry to geothermal.
Geothermal power plants are a source of 24/7 renewable electricity, unlike wind and solar which are variable and dependent on weather conditions. Geothermal energy has traditionally been limited to places with suitable geology and the natural existence of water or steam in the reservoir, but new technologies ("Enhanced Geothermal Systems" or "EGS") are making geothermal resources available and easier to find in more locations. We categorize the geothermal resource as semi-renewable. Although the Earth’s heat is non-depletable, the use of geothermal energy must be carefully managed in each location to prevent water or steam depletion.
Note: Ground source heat pumps are often referred to as geothermal heat pumps, but they are an energy efficiency measure and do not use the geothermal resource. Instead of using the Earth’s heat, these heat pumps use the ground, which maintains a constant temperature (warmer than the winter air and cooler than the summer air), as a heat source or sink, allowing them to be more efficient than air source heat pumps. See our Energy Efficiency and Buildings pages for more information.
Significance
Energy Mix
<1% of world 🌎
<1% of U.S. 🇺🇸
Electricity Generation
<1% of world 🌎
<1% of U.S. 🇺🇸
Global Uses
Direct use heat: 59%
Electricity: 41%
Changes in Global Demand
Direct Use Heat
Increase:
⬆78%
(2016-2021)
Electricity
Increase:
⬆25%
(2016-2021)
Direct Heat (World)
Largest User of Direct Heat
China 57% 🇨🇳
of global geothermal direct heat use
Direct Heat Uses
Swimming and Bathing: 44%
Space Heating: 39%
Greenhouse Heating: 9%
Industrial Applications: 4%
Other: 4%
Highest Direct Heat Penetration
Iceland 90% 🇮🇸
of country’s heating demand is met by geothermal
Electricity (World)
Most Geothermal Electricity Capacity
US 18% 🇺🇸
Indonesia 16% 🇮🇩
of global geothermal electricity capacity
Most Geothermal Electricity Generation
US 20% 🇺🇸
Indonesia 17% 🇮🇩
of global geothermal electricity generation
Highest Geothermal Electricity Penetration
Kenya 44% 🇰🇪
of country’s electricity comes from geothermal
Electricity (US)
Most Geothermal Electricity Generation
California 70%
of US geothermal electricity generation
Highest Geothermal Electricity Penetration
Nevada 10%
of state’s electricity comes from geothermal
Expansion of Geothermal Resources and Technological Improvements
Almost all new geothermal plant additions in the US since 2000 have been binary cycle, which require lower temperature geothermal reservoirs (allowing geothermal to be used in more locations) and emit no greenhouse gasses or air pollution. Binary cycle plants are also being deployed around the world.
US Geothermal Capacity by Plant Technology
Enhanced Geothermal Systems (EGS) are being explored and developed:
- The combination of heat, permeability, and naturally occurring water exists in limited locations
- EGS expands the geographic availability of the geothermal resource by creating permeability and/or adding water in locations where those don’t occur naturally
There are opportunities for geothermal projects to be co-located with other high energy need systems:
- Direct Air Capture (carbon removal) - energy intensive and can be located almost anywhere. With co-location, the geothermal resource can provide lots of 24/7 energy for the Direct Air Capture process
- Lithium Extraction - geothermal brines often contain dissolved lithium
- Data centers - energy intensive and can be located near geothermal plants that provide the 24/7 baseload power they need
Costs of US Geothermal
Unsubsidized LCOE*: $61 - $102/MWh
Subsidized LCOE: $37 - $87/MWh
Geothermal is subsidized in the Inflation Reduction Act and other policies.
*LCOE (levelized cost of energy) - allows for the comparison of different electricity generating technologies
Compare costs with subsidies and for other resources on the Introduction to Renewable Energy Fast Facts
Unlike wind and solar which have been getting increasingly cheaper, geothermal’s costs have remained relatively steady over the last 10 years. Geothermal is just starting to apply technological advances from the oil and gas industry, so is in the early stages, and costs are expected to decline in the coming years.
The costs of the power plant infrastructure and exploration and drilling are the vast majority of geothermal costs, with actual production costs being low.
Drivers
- Abundant resource: heat from the Earth
- Baseload source of energy: can run day and night regardless of weather
- High capacity factor compared to other renewable energy systems (90-95% for new geothermal plants, 78% for all geothermal plants)
- Relatively low climate and environmental impacts
- Technology and practices can be leveraged from oil and gas industry, such as drilling methods
- New EGS* technologies are expanding places where geothermal can be used
Barriers
- Tapping a subsurface resource is inherently risky and very capital intensive
- Site-specific resource (conventional methods require the presence of heat, permeable rock, and water)
- Potential siting challenges, such as NIMBY/BANANA** or insufficient electricity transmission infrastructure
- Resource must be managed to be sustainable: geothermal reservoirs naturally recharge, but can be depleted if over-exploited
- Potential seismicity risk for EGS projects
- Some air emissions possible, including H2S
- Some systems (such as EGS) may require additional water supply
- Weak policy support compared to other technologies, but improving
*EGS (Enhanced Geothermal Systems) - geothermal plants using new technologies to make geothermal electricity economically viable in more locations
**NIMBY - not in my backyard; BANANA - build absolutely nothing anywhere near anything
Climate Impact: Low
- Small amounts of CO2 can be released in some geothermal processes
- New binary systems have zero GHG emissions
Environmental Impact: Low
- Small amounts of air pollution (primarily H2S) can be released in some geothermal processes
- Some EGS projects can pose a low risk of seismicity and require additional water supply
- Can have land and habitat impacts
Before You Watch Our Lecture on
Geothermal Energy
We assign videos and readings to our Stanford students as pre-work for each lecture to help contextualize the lecture content. We strongly encourage you to review the Essential readings and videos before our lecture on Geothermal Energy. Include selections from the Optional and Useful list based on your interests and available time.
Essential
- Why We're Betting on Enhanced Geothermal Electricity. Google. November 28, 2023. (1 min)
Overview of Google's commercial geothermal project with Fervo Energy to help power their operations in Nevada. - Is the Future of Energy...Pouring Water on Hot Rocks in the Ground?. Vox. September 13, 2023. (5 pages)
Explains "enhanced geothermal" and the challenges ahead for geothermal. - This Overlooked Energy Source Could Supply 50% Of Electricity. CNBC. May 6, 2021. (16 min)
A look into the factors causing increasing interest in geothermal energy by both new company startups as well as established traditional oil and gas industry giants. - Geothermal Energy Is Renewable and Powerful. Why Is Most of It Untapped?. DW Planet A. December 18, 2020. (10 min)
An introduction into how geothermal energy can be harnessed for power generation and a look into some of the factors preventing wide-scale adoption. - Batteries Are Dirty. Geothermal Power Can Help. Vox. November 21, 2022. (8 min)
Demand for nickel to make lithium-ion batteries creates environmental and health hazards where it is mined, particularly in Indonesia, an area where there is tremendous geothermal energy potential and subsequently potential for cleaner lithium-ion battery production. - Why Geothermal Energy Is Being Viewed as a Viable Alternative to Fossil Fuels. PBS NewsHour. March 25, 2022. (5 min)
An overview of recent advances in geothermal energy power production innovations and the external factors influencing them.
Optional and Useful
- Geothermal 2021. NEED.org. 2023. (4 pages)
An introduction to geothermal energy, types of geothermal power plants, direct use applications, geothermal economics and environmental impacts. - Renewables 2023 Global Status Report - Geothermal Power and Heat. REN21. 2023. (4 pages)
Annual source for current geothermal energy market and industry trends, installed capacity, and direct use information. - Puna Geothermal Venture. KHON2 News. October 5, 2021. (5 min)
A look into how geothermal energy fits into the State of Hawaii's clean energy goals. - Nearly Half of U.S. Geothermal Power Capacity Came Online in the 1980s. EIA Today in Energy. November 20, 2019. (1 page)
A brief overview showing geothermal capacity additions over time, as well as comparative capacity factors non-fossil fuel utility scale electricity generators. - History of the Geysers. Calpine Corporation. January 28, 2013. (8 min)
History and overview of The Geysers, the first commercial geothermal electric generation unit in the Western Hemisphere. - Drilling Surprise Opens Door to Magma-Powered Electricity. ARSTechnica. January 29, 2014. (2 pages)
An introduction into the concept of magma-enhanced geothermal systems. - Geothermal Energy in the 21st Century: Unconventional EGS Resources. Forge Utah. January 6, 2021. (33 min)
An exploration of unconventional Enhanced Geothermal Systems technologies and their potential for electricity generation.
Our Lecture on
Geothermal Energy
This is our Stanford University Understand Energy course lecture on geothermal energy. We strongly encourage you to watch the full lecture to understand geothermal as an energy system and to be able to put this complex topic into context. For a complete learning experience, we also encourage you to watch / read the Essential videos and readings we assign to our students before watching the lecture.
Presented by: Dawn Owens, Adjunct Lecturer, Civil and Environmental Engineering, Stanford University; Head of Development and Commercial Markets, Fervo Energy
Recorded on: December 1, 2023 Duration: 63 minutes
Additional Resources About
Geothermal Energy
Stanford University
- Stanford Geothermal Program
- Roland Horne - Geothermal energy
- Earth & Planetary Sciences Department
- Dennis Bird - Geothermal energy
- Aeronautics and Astronautics Department
- Debbie Senesky - Geothermal energy
Industry Organizations
Fast Facts Sources
- Energy Mix (World 2022): Energy Institute. Statistical Review of World Energy. 2023.
- Energy Mix (US 2022): US Energy Information Administration (EIA). Total Energy: Energy Overview, Table 1.3. January 2024.
- Electricity Mix (World 2022): Energy Institute. Statistical Review of World Energy. 2023.
- Electricity Mix (US 2022): US Energy Information Administration (EIA). Total Energy: Electricity, Table 7.2a. January 2024.
- Global Uses (2021): REN21. Renewables 2022 Global Status Report, Chapter 3. 2022.
- Changes in Global Demand (2016-2021): REN21. Renewables 2022 Global Status Report, Chapter 3. 2022; REN21. Renewables 2017 Global Status Report, Chapter 2. 2017.
- Largest User of Direct Heat (World 2021): REN21. Renewables 2022 Global Status Report, Chapter 3. 2022.
- Direct Heat Uses (World 2019): REN21. Renewables 2022 Global Status Report, Chapter 3. 2022.
- Highest Direct Heat Penetration (World): International Renewable Energy Agency (IRENA). Geothermal. 2024.
- Most Geothermal Electricity Capacity (World 2022): International Renewable Energy Agency (IRENA). Renewable Energy Statistics 2023: Geothermal Energy Capacity, p 88. 2023; REN21. Renewables 2022 Global Status Report, Chapter 3. 2022.
- Most Geothermal Electricity Generation (World 2021): International Renewable Energy Agency (IRENA). Renewable Energy Statistics 2023: Geothermal Energy Production, p 89.
- Highest Geothermal Electricity Penetration (World 2020): Energy & Petroleum Regulatory Authority (EPRA). Energy and Petroleum Statistics Report, p 11. 2021.
- Most Geothermal Electricity Generation (US 2022): US Energy Information Administration (EIA). Geothermal Explained: State Rankings for Geothermal Electricity Generation. 2022.
- Highest Geothermal Electricity Penetration (US 2022): US Energy Information Administration (EIA). Geothermal Explained: State Rankings for Geothermal Electricity Generation. 2022.
- US Geothermal Capacity by Plant Technology: National Renewable Energy Laboratory (NREL). 2021 U.S. Geothermal Power Production and District Heating Market Report, p 10, Figure 3. 2021.
- Costs of Geothermal (US 2023): Lazard. Levelized Cost of Energy Analysis–Version 16.0, pp 2-3. April 2023; International Renewable Energy Agency (IRENA). Renewable Power Costs in 2022, pp 170-174. 2023.
More details available on request.
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