[kinghorse]

It would seem to be an improvement if you try to manage the environmental effects at a few thousand points (plants) than at over a billion(trucks and autos). I know beans about the technicalities but that's the way it looks to me.

[Blood of Tyrants]

There are other problems with hydrogen gas such as leakage, reactivity, and transportation. Hydrogen is not the magical fix for the environment.

[Donald Rumsfeld Fan]

Exactly right. It moves the point of pollutant emissions from a distributed system to a single points system.

Then net change in emissions will be a function conversion efficiency (fossil fuels to hydrogen) defined as the net increase or decrease for a given fuel/energy requirement.