The idea that an automobile can be "zero emissions" can only be valid if the production of its fuel is accounted.

Any discussion of zero-emissions vehicles that is within current range of possibility seems to be based upon the employment of electrical motors. The two principal methods toward powering these motors appear to be the employment of batteries and the use of so-called "fuel cells."

A fuel cell converts the hydrogen component of a fuel into electricity and water — just as in reverse the application of electricity to water separates it into oxygen and hydrogen.

A fuel cell can work with pure hydrogen or with hydrocarbon fuels.
get quote about how it's easier to transport electrons than molecules article iht about a company wants to develop infrastructure batteries http://www.nytimes.com/2007/10/29/technology/29agassi.html

"Its much easier to transport electrons than octane molecules," he said. Weve already got a grid that goes around the entire world; all we have to do is extend it."