Since the mid-1990s, the emergence of a hydrogen economy and the speed with which it will arrive have been vigorously debated. As a disruptive technology, dominant designs for the production, storage and distribution of hydrogen have not yet been established. Neither have performance characteristics been achieved to compete with the existing combustion engine, though the efficiency and durability of hydrogen fuel cells are improving. This publication highlights the uncertainties involved in making choices about hydrogen and fuel cells in planning the development policies on national energy, environment and transport sector.--Publisher's description.