In the fall of 2003, a few months after President George W. Bush announced a $1.7-billion research program to develop a vehicle that would make the air cleaner and the country less dependent on imported oil, Toyota came to Washington, D.C., with two of them. One, a commercially available hybrid sedan, had a conventional, gasoline-fueled internal-combustion engine supplemented by a battery-powered electric motor. It got about 50 miles to the gallon, and its carbon dioxide emissions were just over half those of an average car. The other auto, an experimental SUV, drove its electric motor with hydrogen fuel cells and emitted as waste only water purer than Perrier and some heat. Which was cleaner?

Answering that question correctly could have a big impact on research spending, on what vehicles the government decides to subsidize as it tries to incubate a technology that will wean us away from gasoline and, ultimately, on the environment. But the answer is not what many people would expect, at least according to Robert Wimmer, research manager for technical and regulatory affairs at Toyota. He said that the two vehicles were about the same.

This article was originally published with the title Questions about a Hydrogen Economy.

Comments