Abstract
Keywords. Hydrogen, Alternative Fuels, Safety, Safety Operation, Transportation
Hydrogen is the most abundant element in the universe, accounting for more than 90% of the molecules and more than 75% of the mass [21]. However due to the small molecule size and high buoyancy, it is not available in it´s free form on Earth. As the simplest element, and the simplest fuel, hydrogen has gained the attention of the automotive industry [2-11] as an environmentally friendly alternative fuel. Automotive companies have already introduced many vehicles powered by hydrogen fuel cells or hydrogen internal combustion engines. In support of the rapid advancements in hydrogen-powered transportation, major oil companies and dispenser manufacturers have started developing the necessary infrastructure. As a fuel, hydrogen is unique. As a gas, hydrogen is odorless, colorless, tasteless, and burns invisibly in sunlight. Solutions such as the odorants used in natural gas are not yet available for automotive hydrogen because the odorants currently available can poison the fuel cell catalyst. Additionally, the lower flammability limit of hydrogen is lower, and the flammability range wider, than fuels such as gasoline. For those reasons, hydrogen safety is essential at all levels - at the fueling station, in the vehicle, and at the operator interface level. Hydrogen production and distribution are beyond the scope of this paper. In this paper we present an overview of hydrogen safety measures and monitoring techniques that are widely in use at hydrogen fueling stations. Special emphasis will be on hydrogen safety at the vehicle level. Some leak detection and sensing technologies are reviewed and some safety mitigation strategies are explained.