In his State of the Union address, President Bush outlined a vision of nonpolluting, hydrogen-powered fuel-cell cars and promised to pony up $1.5 billion over five years to make that vision a reality. Almost everyone, from environmentalists to automakers, agrees that the transition toward hydrogen is a good thing, at least in theory: It is clean, abundant, and could ultimately free the U.S. from ecologically devastating resource extraction and reliance on foreign oil. But it will take at least a decade to surmount all of the technological, economic, and political barriers to developing fuel-cell cars. To date, the technology is still in the early stages and prohibitively expensive, and a whole new fueling infrastructure would have to be built to accommodate the cars. Some environmentalists criticize the Bush “freedom car” plan as too timid and too long-term, thereby letting carmakers off the hook in the present. They also note that fuel-cell cars won’t be a truly clean technology unless the hydrogen used in such cars is generated by clean energy.