"Auto-industry ads depict hydrogen cars as the vehicular route to clean, blue skies. President Bush and Gov. Arnold Schwarzenegger are among their biggest champions. The politicians' enthusiasm for the technology -- a leading proposal to solve global warming -- is shared by many scientists.
But reality could prove more complex, some critics say. Among the problems detailed at the American Geophysical Union conference in San Francisco last week:
-- Hydrogen is a very "leaky" gas that could escape from cars and hydrogen plants into the atmosphere. This could set off chemical transformations that generate greenhouse gases that contribute to atmospheric warming.
-- The extraction of hydrogen for cars from methane, which is currently the richest available source of hydrogen, will generate carbon dioxide, a major greenhouse gas.
-- Hydrogen can also be extracted from ordinary water via a process called electrolysis. However, using current technology, mass electrolysis of water would require intense sources of energy. If those energy sources burn fossil fuels, they, too, would generate greenhouse gases.
These problems are not necessarily showstoppers, and they may be overcome by future technical innovations. In any event, many scientists believe the environmental problems posed by hydrogen cars may prove to be less severe than the problems generated by today's fossil-fuel-dependent cars. But given such issues, some experts are cautioning that much more research is needed before the nation prematurely commits itself to developing the "hydrogen economy."
"I'm supportive of research and development, but we are at least two decades away from (deploying) the vehicles on a mass level," said MIT-educated physicist Joseph J. Romm, a former U.S. Department of Energy official, in an interview. Romm's book, "The Hype About Hydrogen: Fact and Fiction in the Race to Save the Climate," was published earlier this year by Island Press. "Americans are very much believers in technology and optimism, and yet when you look at the compelling details" about hydrogen cars, Romm said, "it doesn't make bloody much sense."
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http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2004/12/20/MNGEPAEI591.DTL