Hydrogen as Fuel

The interest in hydrogen as an alternative transportation fuel stems from its clean-burning qualities, its potential for domestic production, and the fuel cell vehicle's potential for high efficiency (two to three times more efficient than gasoline vehicles). Hydrogen is considered an alternative fuel under the Energy Policy Act of 1992.

The energy in 2.2 lb (1 kg) of hydrogen gas is about the same as the energy in 1 gallon of gasoline. A light-duty fuel cell vehicle must store 11-29 lb (5-13 kg) of hydrogen to enable an adequate driving range of 300 miles or more. Because hydrogen has a low volumetric energy density (a small amount of energy by volume compared with fuels such as gasoline), storing this much hydrogen on a vehicle using currently available technology would require a very large tank—larger than the trunk of a typical car. Advanced technologies are needed to reduce the required storage space and weight.

Storage technologies under development include high-pressure tanks with gaseous hydrogen compressed at up to 10,000 pounds per square inch, cryogenic liquid hydrogen cooled to -423°F (-253°C) in insulated tanks, and chemical bonding of hydrogen with another material (such as metal hydrides). See the fact sheet Hydrogen Storage

2003 In 2003 Tsolakis at Alabama University of Birmingham showed that "partial replacement of the hydrocarbon fuel by hydrogen combined with EGR resulted in simultaneous reductions of smoke and nitrogen oxides emissions (NOx) without significant changes to engine efficiency". Similar results have been presented by a team of scientists from Zhejiang University, China, which found that "a little amount of hydrogen supplemented to the gasoline-air mixture can extend the flammability of the mixture... improving the economy and emissions of engines".