The cleanliness of hydrogen is, in large part, why support for hydrogen vehicles has reached new heights, with President George W. Bush's proposed Freedom Car and Fuel Initiative amounting to $1.7 billion over five years. But although the chemistry of hydrogen-fueled cars is simple, the economic reality of hydrogen is far more complex, enough to forestall hydrogen-powered highways for decades.
"Hydrogen cars are a poor short-term strategy, and it's not even clear that they are a good idea in the long term," said energy scientist Alex Farrell of the University of California, Berkeley.
There are three reasons why hydrogen might be preferred over gasoline.
As Farrell and colleague David Keith, an energy scientist at Carnegie Mellon University in Pittsburgh, noted in the July 18 issue of the journal Science, first, hydrogen releases no pollutants, unlike the burning of oil, coal or gas, whose byproducts can lead to acid rain and smog.
Second, hydrogen releases no carbon dioxide gas, which traps solar heat and that much research links to global warming.
Third, instead of depending on foreign nations and the vagaries of international politics for its oil imports, the United States could manufacture hydrogen and gain energy independence.
"But if you wanted to achieve any of these goals, there are other strategies you could try and they'd probably work better, faster and cheaper," Farrell told United Press International.
For example, Keith and Farrell pointed out, although hydrogen certainly does not release pollutants such as nitrogen oxides, or NOx, into the atmosphere, there are much cheaper ways of controlling air pollution.
"If you calculate how much it would cost to put enough hydrogen cars on the road to reduce NOx emissions by a ton, it's about $1 million," Farrell said. On the other hand, enhanced and more frequent vehicle inspection and maintenance programs to lower dirty emissions "would cost much less, about $5,000 per ton," he explained.
Hydrogen advocates note burning the gas releases no CO2, but Farrell and Keith maintain such arguments gloss over where hydrogen comes in the first place. Current methods of large-scale hydrogen production are powered by burning natural gas, which produces substantial CO2.
In order to replace oil with hydrogen completely, Grant estimated the United States would need to generate some 230,000 metric tons of the gas daily, enough in liquid form to fill 2,200 space shuttle booster rockets. In order to yield enough power from combustion-powered generators to extract all this hydrogen from water -- the most ready source of the gas -- you would need an area about the size of Nevada and the resulting greenhouse gas release would be considerable.
Instead, Grant argues, four nuclear reactors could fill the energy needs of a hydrogen economy. Moreover, the Energy Policy Act of 2003 proposes a novel $1.1 billion nuclear power plant that could generate hydrogen and electricity at the same time. The Senate's energy bill also proposes subsidizing half the cost of six to 10 of these new plants in the United States.
"None of these reactors have been tested," Farrell noted. "It may not work, and even if it works, the public may not accept the nuclear option."
For several decades, Farrell noted a cheaper alternative to reducing carbon dioxide emissions would be to increase fuel economy. "Automobile manufacturers don't need to invest in anything fancy. A wide number of technologies are already on the shelf," Farrell said.
For instance, a 2002 report from the National Academy of Sciences noted 12 to 42 percent improvements in the fuel economy of light-duty vehicles would pay for themselves in lifetime fuel savings. Increased fuel economy also would help reduce dependence on foreign oil.
"If America wants to buy reduced dependence on petroleum, the use of more stringent fuel economy standards that would not significantly change the type of vehicles we drive would cost little to nothing to implement," Farrell said.
Jason Mark, director of the Union of Concerned Scientists clean vehicles program, agreed conventional fuel efficiency improvements would deliver more immediate, cost-effective reductions in emissions.
"However, with the world's automobile population doubling every 25 years, deep cuts in transportation-related global warming gases will ultimately require moving beyond combustion and moving petroleum," Mark told UPI. "We should start that transition today. Thus, we should aggressively pursue hydrogen fuel cells while picking the low-hanging fruit available through more traditional changes to engines, transmissions and vehicles that can improve vehicle fuel economy by two-thirds over the next decade."
Grant also favored a hydrogen economy. He said although it remains unproven fossil fuels are hastening global warming, "the major reason to move to hydrogen is 'no regrets.' Maybe we'll find out carbon dioxide is really bad, even worse than what opponents against emissions say it is. If we start the switch now, then later we won't regret having started."
Farrell predicted there is little chance hydrogen cars will occupy much of the transportation fleet within 25 years, but added it is possible the vehicles could be one of several transportation options after that.
"Obviously you're not going to move from gasoline to hydrogen next month. It's an enormous challenge. It makes the Apollo program pale in comparison," Grant said.
"There will be lots of intermediate steps on the switch in between,," he added. "There's a lot of discussion at the Department of Energy on how we can evolve the system in."