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Fast Facts About

Principal Energy Use: Transportation
Form of Energy: Chemical

Oil is the most-used energy resource worldwide and provides more than 90% of global transportation energy. Because the majority of oil is produced by a limited number of countries, securing access to this resource has significant geopolitical consequences.

Oil (also referred to as petroleum) is a depletable, non-renewable resource burned to convert chemical energy into heat, and a leading contributor to air pollution and climate change. It is a mixture of hydrocarbons found mostly in liquid form in porous rocks beneath the Earth’s surface. The process to extract and produce oil involves prospecting, drilling, completion, and production. Various refined products (e.g., gasoline, diesel, jet fuel) are obtained from processing crude oil, an energy-intensive process.

Because of its high energy density, both by weight and volume, oil is very convenient for transport (where you have to carry your fuel with you). This makes it difficult to replace oil with less energy dense low-carbon alternatives.

Visit our Energy for Transportation; Prospecting for Oil and Natural Gas; Drilling, Completing, and Producing from Oil and Natural Gas Wells; and Gasoline, Diesel, Jet Fuel, etc. pages for more information.

Oil-Fueled Transportation Energy Systems are Highly Inefficient

From 100 units of energy resource, only 10 to 12 units of energy service are provided. The efficiency during the extraction, processing, and transport stages is 98%. Refining efficiency is 80%. Distribution is 98% efficient. And end-use efficiency in an internal combustion engine is 15%.
  • Oil production and refining processes are relatively efficient. Only 25% of production is lost between the well and the fuel pump
  • 86% of the fuel put into an automobile never reaches the wheels. It is lost to engine and driveline inefficiencies, or used to power accessories
  • ​​Less than 1% of the car’s fuel moves the driver


Energy Mix

32% of world 🌎 (#1 resource)
37% of US πŸ‡ΊπŸ‡Έ (#1 resource)

Electricity Generation

2% of world 🌎 (#7 resource)
< 1% of US πŸ‡ΊπŸ‡Έ (#8 resource)

Transportation Energy

91% of world 🌎
90% of US πŸ‡ΊπŸ‡Έ

Change in Global Consumption

Virtually no change:
⬆ 0.2%

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33% of world 🌎
41% of US πŸ‡ΊπŸ‡Έ
energy GHG emissions are from oil
(includes methane leakage)

Energy GHG emissions are ~75% of global GHG emissions.

(Visit our Natural Gas page for more information on methane leakage)

Oil Use for Transportation Is a Major Contributor to Outdoor Air Pollution

Adverse health effects from vehicle exhaust include cancer, cardiovascular disease, respiratory diseases, diabetes mellitus, obesity, and reproductive, neurological, and immune system disorders. 

Particulate matter smaller than 2.5 microns (PM2.5) emissions pose the greatest risk to health. Other pollutants include carbon monoxide (CO), nitrous oxides ( NOx), and ozone (O3). Transport contributes 8% of global and 17% of US PM2.5 emissions. 

Vehicle electrification reduces air pollution and its health effects because most of the exposure is in highly dense urban areas with heavy traffic.


Largest Proved Reserves

Venezuela 18% πŸ‡»πŸ‡ͺ
of global proved reserves

Largest Producer

US 19% πŸ‡ΊπŸ‡Έ
of global production

Largest Consumer

US 20% πŸ‡ΊπŸ‡Έ
of global consumption


Largest Proved Reserves

Texas 41%
of US proved reserves

Largest Producer

Texas 43%
of US production

Largest Consumer

Texas 19%
of US consumption

Global Trade (Crude Oil)

Total Traded

of global production

Largest Exporter

Saudi Arabia 17% πŸ‡ΈπŸ‡¦
of crude oil exports

Largest Importer

China 24% πŸ‡¨πŸ‡³
Europe 24%
of crude oil imports

Leading Refiners

US 18% πŸ‡ΊπŸ‡Έ
China 17% πŸ‡¨πŸ‡³
of petroleum product output (gasoline, jet fuel, diesel, etc.)


  • High energy density in volume and weight of oil; easy to store and transport
  • Few alternatives for transport, especially long-haul trucking, shipping, and aviation
  • Established infrastructure (e.g., fuel stations, refineries, manufacturing plants) 
  • Social and environmental externalities are not accounted for in price
  • Corporate lobby with political influence
  • Innovation in extraction drives down costs and increases available resource (horizontal drilling, hydraulic fracking)
  • Global and US economies are very dependent on oil
  • Desire to maintain economic and political power by exporting countries, including OPEC+


  • Many externalities: oil spills, air pollution, methane leakage, CO2 emissions, water use and contamination, land use
  • Depletable, non-renewable resource
  • National security: geopolitical conditions disrupt supply and price
  • Inefficient; significant losses from well to moving people
  • Public health: GHG emissions, SOx, NOx, etc. impacts near wells, refineries, and pipelines; past use of leaded gasoline
  • Legacy infrastructure and pollution issues with abandoned wells and closed refineries

Climate Impact: High

High gradient
  • Carbon dioxide is released during combustion
  • Methane leaks during extraction and production

Environmental Impact: High

High gradient
  • Ecosystem disturbance from exploratory wells, road construction, seismic techniques of exploration during prospecting
  • Significant land impacts, habitat destruction, and water contamination during extraction
  • Groundwater and soil damage from improper disposal of saline water pumped from the ground and oil and gas leakages from improperly maintained wells
  • High energy and water requirements for extraction and refining
  • Irresponsible oil production can lead to seismicity
  • Oil spills
  • Air pollution from combustion (NOx, SO2, particulate matter, volatile organic compounds)

Before You Watch Our Lecture on

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 Oil. Include selections from the Optional and Useful list based on your interests and available time.


  • Oil Sands 101. Student Energy. May 17, 2015. (3 min)
    Quick overview of Oil Sands / Tar Sands
  • Distillation Basics. Valero Refining 101 Series. October 2, 2020. (4 min)
    Explanation of distillation, a key process in oil refining.
  • How an Oil Tanker Works and Is Designed. 3D Living Studio. May 5, 2023. (8 min)
    See how oil tankers are designed, loaded, and offloaded.
  • Neighbors of the Fence. The Bitter Southerner. May 1, 2015. (18 pages)
    In depth article about the challenges facing oil refineries and fenceline communities in Baton Rouge, LA.

Optional and Useful

Our Lecture on

This is our Stanford University Understand Energy course lecture on oil. We strongly encourage you to watch the full lecture to understand oil 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.

Diana Gragg

Presented by: Diana Gragg, PhD; Core Lecturer, Civil and Environmental Engineering, Stanford University; Explore Energy Managing Director, Precourt Institute for Energy
Recorded on: October 11, 2023   Duration: 67 minutes

Table of Contents

(Clicking on a timestamp will take you to YouTube.)
00:00 Introduction 
05:27 History, Significance, and Markets 
28:58 Oil Sands / Tar Sands 
34:46 Oil (& Liquid Fuels) Trade & Transportation (Midstream) 
47:33 Oil Refining (Downstream)

Lecture slides available upon request.

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Additional Resources About

Stanford University

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