People I know have learned a hell of a lot about journalism when somebody writes an article on a subject in which the reader is very knowledgable (I wish they would remember it when the subject is something they don't know much about.)

That being said, hydrogen isn't a normal fuel as such. Not like oil or biofuels. It's more of a chemical "battery," a system for storing energy that has to be manufactured. A lot of writers forget this. Yeah, I know, if you look a the big picture, oil and biofuels are also chemical batteries for storing solar energy, but you know what I mean.

It's just pushing the energy production issue one step back. There are some advantages--it's easier to generate clean power at centralized locations than in a million cars, for example.

I suspect the NO2 and other pollution issues, which are quite minor, could be easily handled by current anti-pollution car tech.

More critical issues are where the hydrogen comes from, and how it's transported and stored in the vehicles.

I haven't looked at the numbers for energy density, particularly for gaseous hydrogen under pressure, but I'm wondering if battery technology isn't going to overtake hydrogen as a transportation fuel anyway. Its light weight might give it some application in air transport, but the increased size of fuel tanks even for liquid hydrogen makes it a problem, never mind cryogenic issues.