electure,
Your description is not quite correct, but really is something for everyone who likes the idea of electric cars or hydrogen cars to think about.
Most hydrogen is _not_ produced using electricity. Rather it is made _chemically_ using fossil fuel feedstock. For example, you can react natural gas and water in appropriate conditions to produce hydrogen and carbon dioxide.
This, of course, means that hydrogen simply moves the pollution to your hydrogen production factory, rather than eliminating pollution.
In theory, in the future, the hydrogen could be produced electrolytically using renewable electricity sources. This is an important possibility because often the sun is shining or the wind is blowing at a time when you don't need the electricity, so having something to do in order to store that energy (say by making hydrogen) is a great way to use this electricity. But right now hydrogen as a fuel offer no big benefit to the environment.
(Note that there are small benefits, eg. building the hydrogen infrastructure now would enable the 'ideal' use of hydrogen later, and having all of your pollution produced in a central location means that you can do more to capture/treat it, etc...)
Regarding C-H's comparison between batteries and fuel cells, despite _all_ of the hype, they are essentially the same. They are both electrochemical cells, meaning that by letting certain internal reactions run, you can extract electrical power, and by pumping electrical power into the cell, you can cause those reactions to run in reverse.
Fuel cells are simply batteries in which the chemical reagents are separated and in separate storage from the reacting surfaces, whereas in a battery everything is combined into your electrodes. Any advances in fuel cell science will help improve batteries and vice-versa. 'Charging efficiency' of a fuel cell (kWh to produce the H2 to produce 1 kWh should be comparable to the charging efficiency of a battery.
IMHO it is _really_ hard to beat the energy density and convenience of a take full of dead organic matter. This is why the hybrid electric cars are going to win out for a long time yet to come.
-Jon
