Every day, American drivers eat up nearly 7 billion miles of pavement - roughly the distance to Pluto and back - getting where they want to be.
In the process, they consume enough oil to fill more than 150 supertankers. More than half of that oil comes from abroad, weakening the country's economy and complicating its foreign relations. And when burned, every drop spews pollutants that damage health and contribute to global warming.
It can't go on indefinitely. With automobile use rising worldwide, petroleum reserves gradually dwindling and concerns over U.S. dependence on foreign oil increasing, most energy experts agree that a shift away from fossil fuels is inevitable during this century.
President George W. Bush has responded with a $1.7 billion research program to develop hydrogen as America's next energy source. In 20 years, he predicted, Americans will drive cars propelled by hydrogen-powered fuel cells that emit exhaust containing nothing more toxic than pure water.
"Our scientists and engineers will overcome obstacles to taking these cars from laboratory to showroom," Bush said in his last State of the Union address, "so that the first car driven by a child born today could be powered by hydrogen, and pollution-free."
Even so, both enthusiasts and critics of the technology agree that switching from fossil fuels to a hydrogen-based energy infrastructure will be no small feat.
Right now it costs about 10 times as much to operate a hydrogen-powered fuel cell car as it does to run one with an internal combustion engine. And the small amount of hydrogen that is produced today comes from natural gas and other fossil fuels, generated in a process that releases the greenhouse warming gas carbon dioxide into the atmosphere.
To create an environmentally friendly and economically viable hydrogen energy economy, engineers will have to develop a safe and cost-effective way to store and distribute a highly flammable gas, both on board vehicles and throughout a fuel distribution system. They will also have to either develop ways to make hydrogen with renewable energy, or find a way to capture the carbon dioxide released in hydrogen production and keep it out of the atmosphere.
"This is barely the beginning of the learning curve," said Daniel Sperling, director of the Institute for Transportation Studies at the University of California at Davis.
The administration proposes spending a total of $1.7 billion over the next five years on two related lines of hydrogen research: One program funds the development of cars that can run on hydrogen; a second funds the creation of a storage and distribution infrastructure that will keep their tanks topped off. Automobiles are at the center of the administration's hydrogen plan, Department of Energy Assistant Secretary David Garman explains, because of the unsustainability of their fuel source.
"Over the long term a petroleum-free option is eventually required," Garman recently told the House Science Committee. "That's why the president, during his State of the Union address, announced a groundbreaking plan."
Hydrogen power itself is hardly a new idea. Hydrogen fuel cells already propel experimental vehicles and supply power for some buildings. NASA has used them on spacecraft for decades.
Though you can get energy from hydrogen simply by burning it, the most efficient way to harness the element is with a fuel cell. Like a battery, a fuel cell generates electricity with a chemical reaction. The most common type combines hydrogen and oxygen to make water, generating electricity that can be used to drive a motor, light a neon sign or power a computer.
Aside from the water, which is pure enough to drink, there are no byproducts. As advertised, fuel cells are pollution-free.
The hydrogen they run on, however, doesn't necessarily get a seal of environmental approval. The most important thing to understand is that, unlike oil or coal, there are no natural stores of hydrogen waiting to be pumped or dug out of the ground. Hydrogen has to be produced.
Hydrogen can be made from water in a pollution-free process using electricity generated by solar, wind or geothermal power. But that process can usually be done less expensively using electricity generated by fossil fuels such as coal or natural gas.
Cheaper still, in most cases, is extracting hydrogen directly from fossil fuels. Coal, oil and natural gas all consist primarily of carbon and hydrogen, which can be separated from one another with heat. Unless the carbon is captured and isolated from the environment, however, it will combine with oxygen in the atmosphere to produce carbon dioxide, the primary culprit in global warming.
People have even proposed ways to make hydrogen with nuclear power.
"The fundamental question from today's perspective is how to produce hydrogen," said Andreas Schafer, a research associate at the Massachusetts Institute of Technology's Center for Technology, Policy and Industrial Development.
Last year the Department of Energy convened a committee of energy experts, many from auto and oil companies, to draft a National Hydrogen Energy Roadmap that addresses the production issue and many others. As a renewable energy advocate, American Solar Energy Society chairman Mike Niklas felt hopelessly outgunned at the meeting.
"There was hardly anybody there from renewables and there were hundreds of people who represented the coal industry and the nuclear industry," Niklas said. "It was a joke."
Environmentalists complain that the Bush administration is putting too much emphasis on fossil fuels and nuclear power as hydrogen sources, and ignoring pollution-free renewable alternatives.
"They're cutting renewables in the name of hydrogen," said Niklas, a North Carolina builder of solar-powered homes.
The Department of Energy budget request for fiscal year 2004, released in February, calls for dramatic increases in hydrogen research while cutting or holding steady funding for programs devoted to renewable energy and conservation.
Supporters of the plan say that's the best course, because generating hydrogen from natural gas is a well-established technology that is cheaper than making the fuel with renewable energy. It would be foolish, they argue, to simultaneously pursue cost-effective renewable production technologies while building a massive supply infrastructure.
"Once there's a demand for hydrogen, then we can concentrate on renewable hydrogen," said Brian Walsh, technical director of Fuel Cells 2000, a nonprofit advocacy group.
The National Hydrogen Energy Roadmap comes down heavily on the side of fossil fuels, especially natural gas, as the most practical hydrogen source.
It also relies heavily on the future of sequestration technologies that isolate carbon dioxide either underground or deep in the ocean. If any of the current pilot projects work, fossil fuels would suddenly become a much more environmentally benign source of hydrogen.
"There are reasons to believe it should be possible to store this stuff and it won't be able to get back out," said Joan Ogden, a research scientist at the Princeton Environmental Institute. "If it works as people project it might, it could be a relatively low-cost fix."
Ogden's economic analysis shows that even with the additional cost of carbon sequestration, fossil fuels would still be less expensive than renewable sources of hydrogen.
Such analyses frustrate environmentalists, who charge that big oil has co-opted the federal government's hydrogen research budget. The DOE's budget proposes no increase in solar energy research money for 2004, holding steady at just under $80 million. Wind power research falls 5.5 percent from 2003, geothermal loses 3.8 percent and biomass shrinks 18.9 percent.
"Much of next year's proposed spending comes from cutting other renewable energy (research and development) programs. That's not acceptable," Rep. Sherwood Boehlert, R-N.Y., said during a recent House Science Committee hearing.
Until a hydrogen solution materializes, environmentalists advocate conservation measures such as better vehicle fuel economy standards and tax incentives for wind and solar power. They complain that the most recent increase in the Department of Transportation's fuel economy standards - 1.5 miles per gallon over the next three years for light trucks and SUVs - is small compared to what is technically feasible.