Based on the annual consumption of petroleum by the United States for its transportation industry (available from BP), converting that to a hydrogen-fuel equivalent energy, and incorporating the increased efficiency of fuel cells in EVERY VEHICLE....

... I estimate that the United States will have to construct an additional 120 commercial nuclear reactors dedicated to electrolyzing water into hydrogen. This will cost ~ $1.68 trillion for construction, and the public will continue to pay for them long after decommissioning, due to the interest paid on bonds sold to pay for the construction in the first place. In the end it is unknown what the cost of nuclear power is, but in the first ten years is exceeds $4000 per installed kilowatt.

It should also be noted that in all the world there are only 230 nuclear powerplants. And all of those produce ~10,000 metric tonnes of radioactive waste every year, and geological repositories such as Yucca Mountain, when operational, will accept only ~2000 tonnes annually. Increasing the nuclear waste production worldwide by 50% wouldn't be a very good idea. And do you expect the rest of the world to follow the lead of America? Hello?!?! And by the way the fuel tank issue will not be resolved. The most compact storage medium for hydrogen fuel is bonded to carbon (hydrocarbons), which we are currently using (gasoline).

Biomass is the key. It's cheap to produce, in fact it practically grows all by itself. We need to breed a ocean plant that floats on the open sea, so we can make use of more surface area and catch more of the sun's rays. In terms of cost it is the best...

Cost to plant 10,000 acres of corn $30 million

Cost to erect 10,000 acres of solar modules $97 billion + cost of inverters, batteries, transmission lines, etc.

Biomass rules. It is the simplest, most inexpensive, most cohesive plan for energy independence in existence. To make it work we simply need to make sure every vehicle out there is equipped to burn biofuels, by requiring automakers to build only Flexible Fuel Vehicles. That way, consumers have a choice when supplies dry up and prices fluctuate. Right now most vehicles are locked into a petroleum nightmare, unable to mix more than about 10 percent by volume of ethanol with their gasoline, because their engines aren't equipped to burn it properly.