That's according to San Jose State University's Donald Anthrop, professor emeritus of environmental studies at the university and author of more than 60 papers and articles on energy and water resources.

In an "issue briefing paper" published by the Washington, D.C.-based Cato Institute, Anthrop says although hydrogen power is "all the rage" in American politics, policymakers should calculate the environmental costs of harnessing hydrogen for widespread use in the transportation sector before any more taxpayer money is spent.

Advocates of the "hydrogen economy" tout that fuel cells emit only water vapor and heat, and are thus a source of "pollution free" energy.

"This characterization is grossly misleading," says Anthrop, "because it fails to consider the issue of hydrogen production."

Hydrogen is currently produced by two methods; electrolysis and steam reforming, both of which Anthrop contends are grossly inefficient for mass-scale production.

"Replacing 16 quads of gasoline-fired energy with 32 quads of coal-fired energy [the amount he estimates is needed to power the entire U.S. vehicle fleet] to produce electrolysis hydrogen would result in a 2.7-fold increase in carbon emissions," he concludes. "Replacing gasoline with electricity fired by the fuel mix currently employed in the generation sector would increase net carbon emissions from 309 million metric tons to 610 million metric tons."

Meanwhile, the overall energy efficiency of the steam reforming process - the leading current method of hydrogen production - is only about 30%, Anthrop says, "much less than if natural gas were simply burned in an electrical power generating plant."

Inefficiencies aside, about 15 trillion cubic feet of natural gas would be needed to provide the 66.7 billion kilograms of hydrogen needed to power the entire U.S. vehicle fleet, if it were all fuel cell-powered vehicles, he says. That's nearly three times the amount of natural gas currently consumed in the U.S., Anthrop adds.

"The economic problems involved in delivering hydrogen to fuel cells are difficult to remedy because they stem from fundamental thermodynamics," he says. "Although technological improvement may well increase the efficiency with which energy is used along some if not all of the production chain, the challenges are so immense that the confident predictions of imminent economic breakthroughs heard from the political class are hard to take serious."

Before dumping any more tax money into hydrogen-powered fuel cell initiatives - like President George W. Bush's "FreedomCAR" program and California Gov. Arnold Schwarzenegger's (R) plans for a statewide network of hydrogen refueling stations - Anthrop suggest policymakers "get out their calculators and seriously consider the environmental costs of bringing this dream to reality. If they do, they'll find that harnessing hydrogen for widespread use in the energy sector will consume more energy that it will save, and it will worsen, not better, environmental quality."