There are a number of carbon neutral ways of generating hydrogen already; the best tide/wave power system I've seen electrolysed water rather than running cables to shore, and there are some membrane sunlight splitters for desert use.
It's nasty stuff to store, difficult to transport; it can't be liquified like natural gas, the existing pipelines are too permeable to the tiny molecules to be easily, the one-way valves for um gas stations? are ridiculously expensive, occluding it into palladium sponge is heavy and expensive… And the effecient way of using it is in fuel cells, directly producing electricity.
The idea's good, though.