Hydrogen for road transportation: achievements and developments

At the beginning of this millenium, hydrogen appears as a potential energy carrier for the future. Thus, it could serve as a storage medium for renewable energy forms, which should play an increasing part in the world energy supply. In a closer future, hydrogen could also become a fuel for prospective fuel-cell and internal-combustion vehicles. We present here an inventory of the various technologies related to the use of hydrogen in road transportation : propulsion type (fuel cell and electric motor, or internal combustion engine), hydrogen production, on-board storage, infrastructure. Safety, standardization and regulation aspects will also be addressed. Presently, the majority of hydrogen buses are equipped with polymer membrane fuel cells (PEMFC), directly supplied with hydrogen from pressurized vessels (300 bars). On the other hand, car manufacturers are developing various types of experimental vehicles : internal-combustion engine cars with liquid hydrogen storage, fuel cell (PEMFC) cars with storage of hydrogen (liquid, gaseous, hydride) or of methanol. The type of required infrastructured will depend on the type of fuel chosen by the car makers and on the requirements of the oil companies. Several hydrogen supply stations, of different technologies, have already been set up. They deliver gaseous or liquid hydrogen produced by reforming of natural gas or by electrolysis. The building of a hydrogen-based fueling system requires the development of specific means of production, transportation, storage and delivery. Public acceptance will have to be won by guaranteeing safety, reliability, performance and competitivity. Presently, research and development work is mainly carried out on: on-board storage of hydrogen; on-board systems for the production of hydrogen from methanol and petrol; standardization and regulation.