Automakers are showing new interest because key problems with fuel cells—their limited capacity to convert hydrogen to electricity and their susceptibility to freezing—have largely been overcome in recent years. At the same time, the first mass-produced electric vehicles based on batteries—the fuel cell's technological rival for the zero-emissions mantle—have seen sales slow because their range remains disappointing and their prices high.
I've always thought of battery powered cars as a middle man in the evolution toward hydrogen fuel cells. Undoubtedly, electric cars both convinced people to try something new and made the prospect of owning a zero emission vehicle tangible. But there was no chance for them to become the energy source for cars. If you want to drive a long distance, what are you going to do? Swap battery packs? Hang out at the diner for a couple hours while your car charges? That isn't practical.
Now that the kinks are worked out, I'm excited to see an emergence of hydrogen cars. It will take time to get the price down, but they'll get there.