The hydrogen economy has received increasing attention recently. Common reasons cited for investigating hydrogen energy options are improved energy security, reduced environmental impacts, and its contribution to a transition to sustainable energy sources. In anticipation of these benefits, national and local initiatives have been launched in the United States, creating pilot "roadmaps" and technology partnerships to explore hydrogen economy platforms. Although hydrogen can provide several positive improvements over a carbon- or uranium-based energy system, several problems are also likely. As well, competitive technologies (e.g., hybrid vehicles) may offer comparatively greater economic and/or environmental advantages. Before policies to advance a hydrogen energy economy proceed, it is vital that all aspects of hydrogen be compared with other available alternatives. Important questions to ask in this regard are whether a hydrogen economy can fulfill key energy needs and whether there are appropriate roles for hydrogen to play in a sustainable energy future. (Contains 2 figures.)