Hydrogen
Fast Facts About
Hydrogen
Principal Energy Uses: Electricity, Transportation
Hydrogen is a versatile energy currency that can be produced from fossil fuels or water and that also occurs naturally in rocks underground. Hydrogen has very low energy density by volume but is extremely energy dense by weight. Although it is currently used primarily as a feedstock for oil refining, chemicals, and fertilizers, hydrogen shows promise as a clean fuel for heavy-duty transportation, steel-making, heating, and energy storage. Hydrogen is often referred to as the “Swiss Army knife of decarbonization” because it has potential in hard to decarbonize applications; however, it is still nascent and a lot needs to happen (regulatory, tech innovation, infrastructure build-out) before it can contribute to decarbonization.
Today, the vast majority of produced hydrogen is created from fossil fuels, but hydrogen can be created through electrolysis, the process of using electricity to create hydrogen from water. Electrolysis is more expensive than fossil fuel hydrogen and other fuels, but the relative costs are rapidly decreasing due to technological innovation, government subsidies, investment activity, and commercialization.
Geologic hydrogen, hydrogen that occurs naturally in rocks underground, is difficult to detect and has long been overlooked. However, breakthroughs in recent years have generated significant interest and investment in the prospect of geologic hydrogen as an economically viable clean energy source.
Current Status
Categories of Hydrogen*
Brown Hydrogen
Hydrogen produced from coal gasification
Grey Hydrogen
Hydrogen produced from steam methane reforming, a process which converts natural gas into hydrogen and CO2
Yellow Hydrogen
Hydrogen produced from grid electricity through electrolysis
Pink Hydrogen
Hydrogen produced from nuclear energy through electrolysis
*All hydrogen is the same. Colors are assigned based on the environmental impact of how the hydrogen was produced. The colors above are listed in order of their environmental impact. (brown is worst; green, and potentially white/gold, are best).
The Future
Potential Significant Markets
- Steel production
- Trucks, planes, and ships
- Long term energy storage
- Building and industrial heating
- Clean chemicals
Growth of VC Investment in Hydrogen
Increase: ⬆220%
(2018-2023)
2018: $500 million
2023: $1.61 billion
Drivers
- High energy density by weight
- Can be a low to no carbon fuel
- Strong policy support and subsidies for hydrogen production
- Can be paired with renewables to produce zero carbon fuels
- No air emissions when using / burning hydrogen; only byproduct is water
- Potential for long term energy storage
- Potential to decarbonize steel production
- Potential to replace carbon fuels in transportation
- Most abundant element on the planet
- Reduces reliance on imports of fuels
Barriers
- Very low energy density by volume
- Expensive to produce from clean energy (electrolysis)
- Geologic hydrogen is difficult to detect and is not yet economically recoverable, but this is an active area for start-ups and new tech
- Difficult to transport and distribute (hydrogen is only liquid at very high pressure and low temperature)
- One of the most fugitive gases in the world due to small atom size
- Extremely expensive to build necessary infrastructure for hydrogen transportation and storage (e.g., specially sealed pipelines, refueling stations)
- Safety concerns of hydrogen fires
- Lack of public awareness/understanding
Our 10-Minute Take On
Hydrogen
If you're short on time, start by watching this video of key highlights from our lecture on Hydrogen.
Presented by: Diana Gragg, PhD; Core Lecturer, Civil and Environmental Engineering, Stanford University; Explore Energy Managing Director, Precourt Institute for Energy
Recorded: September 12, 2025
Duration: 10 minutes
If you liked this video, watch the other 10-Minute Takes here!
Before You Watch Our Lecture on
Hydrogen
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 Hydrogen. Include selections from the Optional and Useful list based on your interests and available time.
Essential
- Hydrogen 101. Student Energy. May 18, 2015. (3 min)
Quick overview of what hydrogen is and the two main ways we make it (since it’s an energy carrier, not an energy resource, we have to make it). - Your Definitive Guide to Understanding Hydrogen. Cipher. February 28, 2024. (1 page)
A "cheat sheet" for what hydrogen is and why everybody's talking about it now. - The Truth About Hydrogen. DW Planet A. February 25, 2022. (12 min)
Explores the drivers and barriers to hydrogen contributing to a decarbonized future. - Can Hydrogen Help the World Reach Net Zero?. Financial Times. June 13, 2023. (24 min)
Explores the role hydrogen could play in the global push for net zero emissions. - How Does a Fuel Cell Work?. Naked Science Scrapbook. October 7, 2011. (4 min)
Simple demonstration on how fuel cells work. - China moves to supercharge green hydrogen as U.S. pulls back. Canary Media. October 28, 2025. (2 pages)
Explains how China’s new national grants for hydrogen-related industries could accelerate green hydrogen production.
Optional and Useful
- A Treasure Hunt For Underground Hydrogen Is On. Cipher. March 6, 2024. (3 pages)
A look at the recent and rapidly growing interest in searching for geologic hydrogen. - How Much Clean Energy Does It Take To Make Green Steel?. Canary Media. May 22, 2024. (4 pages)
Examines U.S. green steel projects using clean hydrogen. - One Year In, Us Clean Hydrogen Hubs Face Questions — And Have Few Answers. Canary Media. October 16, 2024. (5 pages)
Evaluates the progress and transparency of the $7B U.S. clean hydrogen hubs initiative. - World’s First Entirely Hydrogen-Powered Ferry Welcomes Passengers on July 19 in San Francisco Bay. San Francisco Bay Ferry. July 12, 2024. (2 pages)
Announces the launch of the world’s first commercial passenger ferry powered 100% by hydrogen fuel cells. - NCPA LEC Hydrogen Project. NCPA Power. November 16, 2023. (7 min)
Overview of a Northern California Power Agency project to use green hydrogen by burning it inside of natural gas turbines. - Unique Time in History for Energy and Hydrogen | Dr. Arun Majumdar | Episode 10. Stanford Hydrogen Innovators Podcast. August 2023. (37 min)
Dr. Majumdar's perspective on where hydrogen should and should not play a role in our energy transition. - What is Hydrogen Energy?. McKinsey & Company. October 2, 2024. (4 pages)
Explains what hydrogen energy is and its potential role in decarbonizing major industries. - What Is Green Hydrogen and Will It Power the Future?. CNBC. December 3, 2020. (15 min)
View interviews of experts and policy makers on how hydrogen fits into the future clean energy space.
Our Lecture on
Hydrogen
This is our Stanford University Understand Energy course lecture on hydrogen. We strongly encourage you to watch the full lecture to understand the potential roles of hydrogen in achieving net zero 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: Diana Gragg, PhD; Core Lecturer, Civil and Environmental Engineering; Explore Energy Managing Director, Precourt Institute for Energy, Stanford University
Recorded on: October 28, 2024 Duration: 25 minutes
Table of Contents
(Clicking on a timestamp will take you to YouTube.)
00:00 Introduction
04:35 What is Hydrogen?
15:58 Where Do We Use Hydrogen?
17:15 Where are Things Going in the Future?
Lecture slides available upon request.
Frequently Asked Questions About
Hydrogen
Hydrogen is a versatile energy currency that can be produced from fossil fuels or water and that also occurs naturally in rocks underground. When hydrogen and oxygen react to produce water, energy is released. In a fuel cell, it’s possible to break the reaction into two parts and create electricity. A fuel cell works just like a battery with a much higher capacity that you can recharge by adding more hydrogen.
Hydrogen shows promise as a clean fuel for heavy-duty transportation (trucks, planes, and ships), steel-making, building and industrial heating, long-term energy storage, and clean chemicals. However, it is currently used primarily as a feedstock for oil refining, chemicals, and fertilizers.
Advantages of hydrogen energy include:
- High energy density by weight
- Can be a low to no carbon fuel
- Can be paired with renewables to product zero carbon fuels
- No air emissions when using/burning hydrogen
- Most abundant element on Earth
Disadvantages of hydrogen energy include:
- Very low energy density by volume
- Expensive to produce from clean energy (electrolysis)
- Geologic hydrogen is difficult to detect and not yet economically recoverable
- Difficult to store and transport (hydrogen is only liquid at very high pressure and low temperature; necessary infrastructure is extremely expensive to build
- One of the most fugitive gases in the world due to its small atom size
- Safety concerns of hydrogen fire
- Lack of public awareness/understanding
Hydrogen energy is still nascent and a lot needs to happen (regulatory, tech innovation, infrastructure build-out) before it can contribute to decarbonization. Creating hydrogen from electrolysis rather than from fossil fuels is more expensive, but the relative costs are rapidly decreasing due to technological innovation, government subsidies, investment activity, and commercialization.
Hydrogen is an energy currency, not a primary energy resource, so whether or not it is renewable depends on how it is produced. Almost all hydrogen today is produced from fossil fuels and is not renewable. The very small share of hydrogen produced from water through the process of electrolysis using renewable sources like wind and solar is renewable. Geologic hydrogen, which is difficult to detect and not yet economically recoverable, is continuously produced naturally deep within the Earth when water interacts with certain iron-rich minerals and rocks. However, scientists don’t yet know the rate at which it is generated to determine its renewability.
Additional Resources About
Hydrogen
Government and International Organizations
- International Energy Agency (IEA) Hydrogen
- US Department of Energy (DOE) Hydrogen Program
- US Energy Information Administration (EIA) Hydrogen Explained
- US Hydrogen and Fuel Cell Technologies Office (HFTO)
- US Alternative Fuels Data Center (AFDC) Hydrogen Fueling Station Locations
- California Energy Commission (CEC) Hydrogen Vehicles & Refueling Infrastructure
Fast Facts Sources
- Geologic Hydrogen: Cipher. A Treasure Hunt For Underground Hydrogen Is On. March 6, 2024.
- Hydrogen Sources (2023): International Energy Agency (IEA). Hydrogen: Tracking. 2024.
- Hydrogen Uses (2023): International Energy Agency (IEA). Global hydrogen demand by sector in the Net Zero Scenario, 2020-2030. 2025.
- Change in Global Hydrogen Demand (2019-2023): International Energy Agency (IEA). Global hydrogen demand by sector in the Net Zero Scenario, 2020-2030. 2025.
- Growth in Investment (2018-2023): Pitchbook. Private investment in hydrogen breaks record. 2022; S&P Global. European hydrogen market attracts private equity investment as US deals falter. 2025.