the "hydrogen economy" is a pipe dream and generally a poor idea.
a MUCH more efficient, cheaper, and faster/easier to implement idea would be an "electric" economy, with electric cars and nuclear plants generating the extra electricity we'd need.
whats the point of using electricity to make hydrogen, and then using the hydrogen to fuel cars? it's much more efficient to just use the electricity to power cars directly. the technology is already here, and the distribution system would be much easier to implement. today's electric cars aren't the tiny, slow vehicles that were talked about 10 years ago - advanced in battery technology have allowed us to build vehicles which are quite fast and large enough for a family. you don't hear about it much in the media these days though - all they talk about is the "hydrogen economy" nonsense.