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The Understand Energy Learning Hub is a cross-campus effort of the Precourt Institute for Energy.

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. Projects can (1) directly use high-temperature water or steam for heating buildings, agriculture, aquaculture, and industrial processes or (2) pass it through a turbine to generate electricity.

Geothermal power plants are a rare source of renewable baseload electricity. 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 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.


Energy Mix

<1% of world 🌎
<1% of U.S. 🇺🇸

Electricity Generation

<1% of world 🌎
<1% of U.S. 🇺🇸

Global Uses

Direct use heat: 57%
Electricity: 43%

Global Demand

Direct Use Heat
Significant increase:

Significant increase:


Most Installed Heat Capacity

China 47% 🇨🇳
of total global installed geothermal heat capacity

Direct Heat Uses

District Heating: 49%
Swimming and Bathing: 40%
Food Production: 11%

Highest Heat Penetration

Iceland 90% 🇮🇸
of country’s heat comes from geothermal

Most Electricity Generation

USA 20% 🇺🇸
of total global geothermal electricity

Highest Electricity Penetration

Kenya 41% 🇰🇪
of country’s electricity
comes from geothermal


Most Electricity Generation

California 71%
of total U.S. geothermal electricity

Highest Electricity Penetration

Nevada 9%
of state’s electricity comes from geothermal


  • 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)
  • 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


  • Site-specific resource with limited locations (conventional methods require heat, permeable rock, and water)
  • Tapping a subsurface resource is inherently risky and very capital intensive
  • Potential siting challenges, such as NIMBY/BANANA* or insufficient electricity transmission infrastructure
  • Resource must be managed: 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
  • Connection to electrical grid is too long and expensive
  • Permitting can be convoluted, repetitive, and long as compared to other renewables and oil and natural gas infrastructure

*NIMBY - not in my backyard; BANANA - build absolutely nothing anywhere near anything
**EGS (Enhanced Geothermal Systems) - geothermal plants using new technologies to make geothermal electricity economically viable in more locations

Climate Impact: Low

Low gradient
  • Near-zero greenhouse emissions

Environmental Impact: Low

Low gradient
  • Small amounts of air pollution (primarily H2S) in some geothermal processes
  • Some EGS projects can pose a low risk of seismicity and require additional water supply

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.


Optional and Useful

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.

Tim Latimer

Presented by: Tim Latimer, CEO, Fervo Energy
Recorded on: November 16, 2022.  Duration: 78 minutes

Table of Contents

(Clicking on a timestamp will take you to YouTube.)
00:00 Introduction
09:03 The Geothermal Resource
32:14 Geothermal Electricity
1:02:18 Direct Use of Geothermal Heat
1:04:59 Ground Source Heat Pumps
1:07:10 Geothermal is Poised for Growth
1:09:59 Q and A

Embed Code

Additional Resources About
Geothermal Energy

Government and International Organizations

Fast Facts Sources
Electricity Mix: World 2021 (BP Statistical Review of World Energy 2022), U.S. 2021 (BP Statistical Review of World Energy 2022)
Global uses: World 2021 ( Ren21 “Renewables 2021 Global Status Report”)
Demand, Direct Use: World 2015-2020 ( J. W. Lund and A. N. Toth, “Direct utilization of geothermal energy 2020 worldwide review”)
Demand, Electricity: World 2016-2021 (IRENA Renewable Energy Statistics 2022)
Most Installed Heat Capacity: China 2020 ( Ren21 “Renewables 2021 Global Status Report”)
Direct Uses: World 2015 ( J. W. Lund and A. N. Toth, “Direct utilization of geothermal energy 2015 worldwide)
Geothermal Heat Penetration: (IRENA "Geothermal")
Most Installed Electricity Capacity: USA 2021 (IRENA Renewable Energy Statistics 2022)
Most Electricity Generation: USA 2021 (IRENA Renewable Energy Statistics 2022)
Geothermal Electricity Penetration: Kenya 2021 (Energy & Petroleum Regulatory Authority, “The Energy and Petroleum Statistics Report 2021” )
Most Installed Electricity Capacity in the USA: California 2021 (Department of Energy "2018 Renewable Energy Data Book")
Most Electricity Generation in the USA: California 2021 (IEA "Geothermal Explained")
Geothermal Electricity Penetration in the USA: USA 2021 (IEA "Geothermal Explained")
More details available on request.
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