Hydrogen (H2) is a potentially emissions-free alternative fuel that can be produced from domestic resources. Although not widely used today as a transportation fuel, government and industry researchers are working toward the goal of clean, economical, and safe hydrogen production and fuel-cell electric vehicles.
Hydrogen is locked up in enormous quantities in water (H2O), hydrocarbons (such as methane, CH4), and other organic matter. Efficiently producing hydrogen from these compounds is one of the challenges of using hydrogen as a fuel.
Currently, steam reforming of methane (natural gas) accounts for the majority of the hydrogen produced in the United States. Almost all of the hydrogen produced here each year is used for refining petroleum, treating metals, producing fertilizer, and processing foods. Hydrogen has been used for space flight since the 1950s.
Hydrogen also can be used to power fuel cell electric vehicles, which are zero-emission vehicles. Major research and development efforts are aimed at making fuel cell electric vehicles practical for widespread use.
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 electric vehicles, its potential for domestic production, and the fuel cell vehicle's potential for high efficiency-it's two to three times more efficient than an internal combustion engine.
The energy in 2.2 pounds (1 kilogram) of hydrogen gas is about the same as the energy in 1 gallon of gasoline. Because hydrogen has a low volumetric energy density, it is important for a fuel cell vehicle to store enough fuel onboard to have a driving range comparable to conventional vehicles. Some hydrogen storage technologies are available and undergoing more research and demonstration. These technologies include compressing gaseous hydrogen in high-pressure tanks at up to 10,000 pounds per square inch. Other storage technologies are under development, including bonding hydrogen chemically with a material such as metal hydride, or low temperature sorbent materials.
More Information Located on the Alternative Fuels Data Center