Hydrogen Basics

Hydrogen (H2) is an alternative fuel that can be produced from diverse domestic resources. Although hydrogen is in its infancy in the market as a transportation fuel, government and industry are working toward clean, economical, and safe hydrogen production and distribution for widespread use in fuel cell electric vehicles (FCEVs). FCEVs are beginning to enter the consumer market in localized regions domestically and around the world. The market is also developing for buses, material handling equipment (such as forklifts), ground support equipment, medium- and heavy-duty vehicles, and stationary applications. 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 of the challenges of using hydrogen as a fuel comes from being able to efficiently extract it from these compounds.

Currently, steam reforming, combining 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. This is more energy intensive but can take advantage of inexpensive excess renewable energy, such as wind or solar, while avoiding the harmful emissions associated with other kinds of energy production.

Almost all of the hydrogen produced in the United States each year is used for refining petroleum, treating metals, producing fertilizer, and processing foods.

Although the production of hydrogen may generate emissions affecting air quality, depending on the source, a 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 initial rollout of production vehicles in northern and southern California, and more recently in the northeastern states in 2018.

Learn more about hydrogen and fuel cells from the 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 FCEVs, its potential for domestic production, its fast filling time, and the fuel cell's 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). For example, the FCEVs in production 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 about 5 minutes. Other storage technologies are under development, including bonding hydrogen chemically with a material such as metal hydride, or low-temperature sorbent materials. Learn more about hydrogen storage.

Chart showing FCEV fueling times. The average fueling time is 3.7 minutes with 37% of fueling times less than 3.3 minutes and 15% of fueling times more than 2.5 minutes. DOE's target for 2020 is 5kg of fuel delivered, and DOE's ultimate target is 5kg delivered in 2.5 minutes.

Data from retail hydrogen fueling stations, collected and analyzed by the National Renewable Energy Laboratory, show the average time spent fueling an FCEV is less than 4 minutes.

California is leading the nation in funding and building hydrogen fueling stations for FCEVs. As of mid-2018, there were 35 retail hydrogen stations open to the public in California and 22 more in various stages of construction or planning. California continues to provide funding for building the infrastructure, with the Energy Commission having authorization to allocate up to $20 million per year through 2024 until there are at least 100 operational stations. In addition, 12 retail stations are planned for the northeastern states, and some of these should be open by the end of 2018. Non-retail stations in California and throughout the country also continue serving FCEVs, including buses, for research or demonstration purposes. Also, multiple distribution centers across the country dispense hydrogen to material-handling vehicles in their normal operations. Vehicle manufacturers are only offering FCEVs to consumers who live in regions where hydrogen stations exist. Find hydrogen fueling stations across the U.S.