Hydrogen technologies have experienced cycles of excessive expectations followed by disillusion.Nonetheless, a growing body of evidence suggests these technologies form an attractive option forthe deep decarbonisation of global energy systems, and that recent improvements in their cost andperformance point towards economic viability as well. This paper is a comprehensive review of thepotential role that hydrogen could play in the provision of electricity, heat, industry, transport andenergy storage in a low-carbon energy system, and an assessment of the status of hydrogen in beingable to fulfil that potential. The picture that emerges is one of qualified promise: hydrogen is wellestablished in certain niches such as forklift trucks, while mainstream applications are now forthcoming.Hydrogen vehicles are available commercially in several countries, and 225,000 fuel cell home heatingsystems have been sold. This represents a step change from the situation of only five years ago. Thisreview shows that challenges around cost and performance remain, and considerable improvements arestill required for hydrogen to become truly competitive. But such competitiveness in the medium-termfuture no longer seems an unrealistic prospect, which fully justifies the growing interest and policysupport for these technologies around the world.
The role of hydrogen and fuel cells in the global energy system