Hydrogen Basics
Hydrogen (H2) is an alternative fuel that can be produced from diverse domestic resources, including renewables, and is expected to play an important, multi-pronged role in decarbonizing the transportation sector. To that end, government and industry are working toward clean, economical, and safe hydrogen production and distribution for use in transportation applications that cannot easily be decarbonized through electrification with batteries, such as 24-hour operations, long-haul operations, and operations in locations where the electric grid cannot economically support battery electric vehicles. Research and development is underway to reduce cost and improve performance of both fuel cell electric vehicles (FCEVs) and hydrogen internal combustion engine vehicles. Opportunities to use hydrogen fuel cells to produce power for charging battery electric vehicles are also being investigated.
Light-duty FCEVs are now available in limited quantities to the consumer market in localized regions domestically and around the world. The market is also emerging for buses, material handling equipment (such as forklifts), ground support equipment, medium- and heavy-duty trucks, marine vessels, and stationary applications. Reserach is also being conducted on hydrogen for aircraft auxiliary power and propulsion. For more information, see fuel properties and the Hydrogen Analysis Resource Center.
Hydrogen is abundant in our environment. It's stored in water (H2O), hydrocarbons (such as methane, CH4), and other organic matter. One challenge of using hydrogen is efficiently isolating it from these compounds.
Currently, steam reforming—reacting high-temperature steam with natural gas to extract hydrogen—accounts for the majority of the hydrogen produced in the United States. Hydrogen can also be produced from water through electrolysis. Electrolysis is more energy intensive than steam reforming but can be done using renewable energy, such as wind or solar, avoiding the greenhouse gas and harmful air pollutant emissions associated with reforming.
Today, almost all the hydrogen produced in the United States each year is used for refining petroleum, treating metals, producing fertilizer, and processing foods. However, the U.S. National Clean Hydrogen Strategy and Roadmap, developed by the U.S. Department of Energy in collaboration with multiple other Federal agencies, identifies numerous opportunities for clean hydrogen to support a decarbonized future energy system, including heavy-duty transportation, the production of liquid fuels for marine and aviation applications, renewable grid integration with storage and other ancillary services, long-duration energy storage, and many other opportunities.
Although some methods of hydrogen production generate emissions affecting air quality and greenhouse gas emissions, depending on the source, an FCEV running on hydrogen emits only water vapor and warm air as exhaust and is considered a zero-emission vehicle. Major research and development efforts are aimed at making these vehicles and their infrastructure practical for widespread use. This has led to the rollout of light-duty vehicles to retail consumers, as well as implementation of medium- and heavy-duty buses and trucks in California and fleet availability in northeastern states.
Learn more about hydrogen and fuel cells from the Hydrogen and Fuel Cell Technologies Office.
Hydrogen as an Alternative Fuel
Hydrogen is considered an alternative fuel under the Energy Policy Act of 1992. The interest in hydrogen as an alternative transportation fuel stems from its ability to power fuel cells in zero-emission vehicles, its potential for domestic production, and the fuel cell electric vehicle's fast filling time and high efficiency. In fact, a fuel cell coupled with an electric motor is two to three times more efficient than an internal combustion engine running on gasoline. Hydrogen can also serve as fuel for internal combustion engines. However, unlike FCEVs, these produce tailpipe emissions and are less efficient. Learn more about fuel cells.
The energy in 2.2 pounds (1 kilogram) of hydrogen gas is about the same as the energy in 1 gallon (6.2 pounds, 2.8 kilograms) of gasoline. Because hydrogen has a low volumetric energy density, it is stored onboard a vehicle as a compressed gas to achieve the driving range of conventional vehicles. Most current applications use high-pressure tanks capable of storing hydrogen at either 5,000 or 10,000 pounds per square inch (psi). At 5,000 psi hydrogen is marketed as H35 (35 megapascals, which is equal to 5,000 psi) and at 10,000 psi hydrogen is marketed as H70. The light-duty FCEVs produced by automotive manufacturers and available at dealerships have 10,000 psi tanks. Retail dispensers, which are mostly co-located at gasoline stations, can fill these tanks in 3–5 minutes. Fuel cell electric buses currently use 5,000 psi tanks that take 10–15 minutes to fill. Other ways of storing hydrogen are under development, including bonding hydrogen chemically with a material such as metal hydride or low-temperature sorbent materials. Learn more about hydrogen storage.
California is leading the nation in building hydrogen fueling stations for FCEVs. As of 2024, 54 retail hydrogen stations were open to the public in California, as well as one in Hawaii, and over 20 more were in various stages of construction or planning in California. These stations are serving nearly 15,000 FCEVs. California continues to provide funding toward building hydrogen infrastructure through its Clean Transportation Program. California Assembly Bill 126, which extends the Clean Transportation Program through July 1, 2035, directs the California Energy Commission to allocate at least 15% of its Clean Transportation Program funds for light-, medium-, and heavy-duty vehicle hydrogen fueling.
While retail stations are planned for some midwestern and northeastern states, with some of those already serving fleet customers. In 2023, the U.S. Department of Energy selected seven Regional Clean Hydrogen Hubs (H2Hubs) to continue expanding FCEV fueling infrastructure beyond California. These H2Hubs will collectively receive up to $7 billion through the Bipartisan Infrastructure Law to deploy clean hydrogen production and delivery infrastructure, which will form the foundation of a national clean hydrogen network to support decarbonization of multiple sectors of the economy, including heavy-duty transportation.
Vehicle manufacturers are currently offering FCEVs to consumers who live in regions where hydrogen stations exist. Non-retail stations in California and throughout the country also continue serving FCEV fleets, including buses. Multiple distribution centers are using hydrogen to fuel material-handling vehicles in their normal operations. There are currently nearly 70,000 fuel cell forklifts in the United States, as they offer an emissions-free option that can be fueled quicly and easily to meet run-time requirements and doesn't require as much maintenance as lead-acid batteries. In addition, several announcements have been made regarding the production of heavy-duty vehicles, such as line-haul trucks, that will require fueling stations with much higher capacities than existing light-duty stations. Many of these vehicles will begin testing and service in 2024 to meet Advanced Clean Trucksregulations. Find hydrogen fueling stations across the United States.
