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

Introduction to Fossil Fuels

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Fast Facts About
Fossil Fuels

Principal Energy Uses: Electricity, Heat, Transportation
Form of Energy: Chemical

The three fossil fuels are oil, natural gas, and coal. Fossil fuels are hydrocarbons formed from deeply-buried, dead organic material subject to high temperature and pressure for hundreds of millions of years. They are a depletable, non-renewable energy resource.

Fossil fuel combustion (converting chemical energy into heat) powered the Industrial Revolution and is the largest contributor to climate change and air pollution. Significant infrastructure, economic value, geopolitical conflict, and legacy environmental issues are associated with fossil fuels.


Energy Mix
82% of world 🌎
82% of US 🇺🇸

Electricity Generation
60% of world 🌎
61% of US 🇺🇸

Fossil Fuel Dependence of Global End Uses
95% of transportation
>60% of heat
60% of electricity
is provided by fossil fuels

Change in Global Consumption
⬆ 3%

GHG Emissions Attributed to Fossil Fuels
74% of world 🌎
82% of US 🇺🇸

Stages and Impacts of Fossil Fuel Utilization

Exploration and Extraction

Drilling and mining impact natural ecosystems and nearby communities.

Transportation, Storage, and Refining

Transportation of fossil fuels expends energy: coal is moved by rail, barge, or truck, while pressurized pipelines deliver natural gas and crude oil.

Oil requires refining into other petroleum products such as gasoline, diesel, and jet fuel before it can be used. Refining is an extremely energy-intensive process.

Combustion and Post‑Combustion

Burning fossil fuels for electricity, heat, and transportation is one of the most polluting human activities, releasing greenhouse gases (CO2), air pollutants (NOx and SO2), and toxins. Power plants also use water for cooling.

After combustion, pollutants such as coal ash require management and disposal. Air pollutants can be removed from the smokestack.

Legacy Impacts and Issues

Abandoned infrastructure (mines, wells, and refineries) associated with all of the previous stages can cause ongoing environmental problems that outlast the production and use of fossil fuels.

Millions of oil and gas wells and coal mines that are no longer producing still remain. If not properly decontaminated and sealed, they continue polluting the environment.

Proved Fossil Fuel Reserves

Proved Oil Reserves

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Pie chart using 2020 data to show the countries in which global proved oil reserves are located. Canada total includes oil sands (95% of Canada's proved reserves).

70% of proved oil reserves are in OPEC nations: Venezuela, Saudi Arabia, Iran, Iraq, Kuwait, and Other OPEC.

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Pie chart using 2021 data to show the states in which US proved oil reserves are located.

70% of the US’s proved reserves are located in just 4 states - Texas (41%), North Dakota (11%), New Mexico (11%), and Alaska (8%).

Proved Natural Gas Reserves

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Pie chart using 2020 data to show the countries in which global proved natural gas reserves are located.

59% of proved reserves are concentrated in the Middle East and Russia.

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Pie chart using 2021 data to show the states in which US proved natural gas reserves are located.

Estimates of Pennsylvania's resources have increased ~30x since 2008 due to the Marcellus and Utica shales. The US is the largest producer and consumer of natural gas in the world.

Proved Coal Reserves

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Pie chart using 2021 data to show the countries in which global proved coal reserves are located.

Five countries have 75% of the world's proved coal reserves.

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Pie chart using 2022 data to show the states in which recoverable coal reserves are located.

75% of US proved coal reserves are located in just 4 states–Wyoming, Illinois, West Virginia, and Pennsylvania.

Fossil Fuel Producers and Consumers

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  • Abundant and widely available
  • Relatively low private costs (but high social and environmental costs are not factored into the price)
  • Ongoing innovation in extraction drives down costs and increases available resources
  • Government interventions (e.g., subsidies and low taxes) have significantly increased the growth of fossil fuel use (with huge social costs)
  • Easy to store and transport (via pipeline, ship, rail, truck)
  • Sunk cost and existing infrastructure motivate continued use
  • When used for electricity generation, considered a flexible/dispatchable resource that can be ramped up and down based on needs of the electricity grid
  • Few non-fossil substitutes for transportation fuels


  • Depletable and non-renewable
  • Largest source of greenhouse gas emissions and air pollutants
  • Public health impacts near sites of fossil fuel production and consumption
  • Fuel prices are volatile, reliant on geopolitical conditions
  • Legacy issues with abandoned infrastructure (e.g., wells, mines, pipelines, refineries) and solid waste (e.g., mine tailings, metal catalysts used in refining, coal ash)
  • Many other externalities, including oil spills, methane leakage, water use and contamination, inter-state conflict

Climate Impact: High

High gradient
  • Carbon emissions released during fossil fuel combustion are the single-largest driver of climate change
  • Methane leakage during oil, natural gas, and coal extraction or from natural gas pipelines

Environmental Impact: High

High gradient
  • Fossil fuel combustion is a major source of air pollution: SO2 (acid rain), NOx (acid rain and smog), CO, particulate matter, and toxins (e.g., mercury)
  • Habitat destruction during extraction, water contamination during transportation, high water use in combustion

Updated March 2024

Before You Watch Our Lecture On
Introduction to Fossil Fuels

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 videos and readings below before watching our lecture on Introduction to Fossil Fuels. Include selections from the Optional and Useful list based on your interests and available time.


Optional and Useful

Our Lecture on
Introduction to Fossil Fuels

This is our Stanford University Understand Energy course lecture that introduces fossil fuel energy resources: coal, oil, and natural gas. We strongly encourage you to watch the full lecture to understand the origins of fossil fuels, how they work, and their significant role in the global energy landscape. 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.

Jane Woodward

Presented by: Jane Woodward, Adjunct Professor, Civil and Environmental Engineering, Stanford University; Founder and Managing Partner, WovenEarth Ventures; Founding Partner, MAP Energy
Recorded on: October 2, 2023  Duration: 30 minutes

Table of Contents

(Clicking on a link will take you to YouTube.)
00:00 Introduction 
03:35 Relevance and Origin 
18:36 Resources and Reserves 
24:41 Environmental Impacts

Lecture slides available upon request.

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Additional Resources About
Fossil Fuels

Stanford University

Government and International Organizations

Fast Facts Sources

More details available on request.
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