There is another issue to address that really is at the root of the 'hydrogen economy:' the difficulties in transitioning from one source of energy to another. Let's face it, no one would pay more for a vehicle powered by hydrogen under the conditions we have today. People will want gasoline-powered vehicles and any transition to another fuel source will be expensive. Hydrogen isn't like a liquid fossil fuel to store and handle, so the safety codes and gas station tanks and equipment would demand more new designs and implementation than something like gasohol.
Ethanol is way too unrealistic for practical use of a large scale in the US and with corn, but there are situations where it would make sense to use biodiesel fuel using waste products. That is only a way to make use of something that otherwise would have been lost, but unrealistic on a large scale. Vegetable oil is expensive compared to gasoline, but when it is to be disposed of; what little there is happens to be a good way to scavenge a little more energy that wasn't there before.