Agree with shields, I believe Hydrogen in the next form of transportable energy when oil fields dry up.Here the comparison should be between storage batteries Vs liquefied Hydrogen for +15 kw energy requirements. We will not and should not abandon it just because technology for a Hydrogen system now has not reached a stage one should like to have. Li battery if proved to be viable will serve as the intermediary solution , just to escape the immediate gas/diesel solution for Automobiles , not to mention the possible ecological problems that may come up. China's recent troubles facing the enormous storage battery recycling/ disposal problems with the lead related batteries used in their electric two wheelers now engulfing their streets is a pointer to the future likely headaches environmentalist may face with Lithium batteries.
There are a number of possible green ways for generation of Hydrogen under study, a combination of solar power being the most attractive. When it will be practical is not a question that cannot be answered easily.