Prospects of Hydrogen-Fuelled Cars

Abstract

Hydrogen has been considered a prospective fuel for future generations of cars. In the present review, various aspects of its use in this field are mentioned. Hydrogen is pure, i.e., it does not produce carbon dioxide in combustion. Moreover, it possesses a very high energy density. In contrast to fossil fuels, hydrogen is an energy carrier, i.e., it is first produced by an energy-consuming process, such as water electrolysis. In hydrogen-fuelled cars, it can be directly supplied into the combustion engine or converted to electric power in fuel cell. Hydrogen-fuelled cars are equipped with a safe and efficient hydrogen storage system. Various ways of hydrogen storage have been studied such as liquid or high-pressure hydrogen storage and storage in solid metal hydrides or in porous materials with high specific surfaces. The first two methods are currently used in the prototypes of hydrogen vehicles. The use of liquid or high-pressure hydrogen requires expensive infrastructure. Hydrogen storage in the form of light metal hydrides (MgH₂, LiBH₄, NaBH₄, NaAlH₄, Mg(AlH₄)₂) is a promising and safe alternative. The hydrides are stable at room temperature but they decompose to hydrogen at elevated temperatures or in the reaction with water. Unfortunately, their costs are high. At present, inexpensive methods of hydride preparation are the subject of extensive studies all over the world.