Hydrogen hot air: polluting with cleaner cars.

PRESIDENT BUSH'S State of the Union address included a proposal to spend $1.2 billion developing hydrogen-powered cars. California Gov. Arnold Schwarzenegger is so taken with the idea that he wants to open a statewide network of hydrogen fueling stations.

Hydrogen cars are a popular environmental cure-all because they are supposed to dramatically reduce greenhouse gas emissions. A simulation for the Reason Foundation, conducted by chemical engineer William Korchinski of Advanced Industrial Modeling, attempted to estimate the decline in carbon dioxide emissions that would have resulted from switching every car in California to hydrogen fuel in 1981. He found that the decline would likely not even be measurable. A comprehensive comparison of the emissions released by hydrogen and gasoline vehicles, as well as those caused by the manufacture, transport, and distribution of both fuels, shows that in most cases fueling cars with hydrogen would make little net difference in emissions of greenhouse gases, and in some cases would even increase them.

For example, hydrogen is made via electrolysis or by reforming hydrocarbons, and both methods take a lot of electricity--most of which comes from burning fossil fuels. And hydrogen can't be sent through pipelines, meaning more truck trips to haul hydrogen to fueling stations.

New cars have very low emissions, and hybrid gas-electric vehicles already on the market emit even less. Yet the kind of incremental improvements that drive so much real progress aren't as exciting to many environmentalists--and presidents--as flashy silver-bullet solutions.