> It sounds great until you realize the only viable way to get large amounts
> of hydrogen is to extract it from natural gas or petroleum.  At that point
> you realize hydrogen puts us back where we started, except with a lower
> overall efficiency.

Not if fuel cell technology and H2 infrastructure are well implemented.  Check out this link for info that helps dispell myths about the upcoming hydrogen economy (very dense but worth it):

http://www.rmi.org/images/other/Energy/E03-05_20HydrogenMyths.pdf