Top Gear <3 Honda FCX Clarity Hydrogen Car
British cult car show Top Gear has just test-driven the Honda FCX Clarity hydrogen fuel cell car, and they were quite impressed. In fact, in a segment they call "The Future of the Car" they call it "the most important car for a 100 years." But there's a problem wit that... Read on for more, including the video of the Top Gear segment.
They just hand-wave over the problem of where to get hydrogen. Even if you can make the fuel cell itself a lot less expensive and get a fuel cell car in every garage (and many teams of brilliant scientists and engineers are working on just that, though we aren't there yet and the FCX is probably a million dollar car), you still need to fuel them.
It takes quite a bit of energy to perform electrolysis on water to split the oxygen from the hydrogen, and then it takes some more energy to compress the hydrogen for use in a car. Where is that energy going to come from? And if we were to have that much energy, could it not be used to directly charge the batteries of electric cars, which keep improving slowly but surely. By the time hydrogen fuel cells are affordable, battery electric cars will be much better than they are now.
You could also get hydrogen from natural gas (which would be more efficient than burning gasoline from a CO2 perspective, though that's assuming fuel cells are affordable), but you're back to having a fossil fuel problem (not to mention the national security problems this could cause to many countries, making them even more dependent on natural gas producers).
Another potential scenario is genetically modified organisms that produce hydrogen. This is promising, but we're not quite there yet.