Thirsty? Imagine bending down to your car tailpipe and taking a big slurp.
Hydrogen-powered vehicles could make that possible (though you'd probably prefer to get your drinking water elsewhere). Unlike gasoline-driven combustion engines, the hydrogen fuel cell generates power not by burning, but through a chemical reaction in which hydrogen and oxygen are converted into energy with water as the only byproduct. It's not just clean, as a fuel source, hydrogen offers nearly three times the energy of gasoline since it burns hotter and faster.
The concept of such a clean car is appealing, but a growing number of critics are saying it's time to wake up and embrace technologies, such as gas-electric hybrid vehicles, that they say are more feasible.
"The things that matter here are energy security, climate change and air pollution," said David Keith of the Department of Engineering and Public Policy at Carnegie Mellon University in Pittsburgh. "Focusing on fuel-cell cars makes no economic sense for any of these goals."
President Bush declared in his 2003 State of the Union address that he aimed to have hydrogen-powered cars on the road in significant numbers by 2020 and pledged $1.2 billion in federal money for the effort. The energy department followed up this year by including $318 million for both fuel cells and hydrogen production in its 2005 budget.
Thinkers like Jeremy Rifkin of the Foundation on Economic Trends argue that adopting a hydrogen-fueled economy could not only lead to cleaner skies, but also liberate the country from its dependence on foreign oil and make energy more accessible to the masses. This is because each hydrogen fuel-cell vehicle contains the parts to essentially be a portable power plant. This means that when not in motion, cars could be hooked up to help power outside units.
"In the new hydrogen fuel-cell era, even the automobile itself is a 'power station on wheels' with a generating capacity of 20 kilowatts," he wrote in his book, "The Hydrogen Economy: The Creation of the Worldwide Energy Web and the Redistribution of Power on Earth."
But in the past year, two reports, one from the National Academy of Sciences and another in the journal "Science," plus a recently published book have all argued that placing such focus on hydrogen fuel-cell vehicles may be counterproductive. A better, more viable solution could lie in a technology that is already catching on -- the hybrid vehicle.
"We already have a technology that can reduce emissions by 30 (percent) to 50 percent," said Joseph Romm, chief official for alternative fuels for the Department of Energy under President Clinton and author of the book "The Hype About Hydrogen: Fact and Fiction in the Race to Save the Climate." "So I think hybrids, not fuel cells, should be the focus of government policy for the next two decades."
Romm and others point out that hydrogen is a fuel carrier, not a fuel source, which means it must be produced from other sources. While the hope is renewable resources, such as windpower, might someday be used to produce hydrogen, right now the most cost-efficient way of making it is from natural gas in a process that releases carbon dioxide into the atmosphere. And that, critics say, defeats the purpose of switching to hydrogen in the first place.