The facts do remain that H2 is more reactive and dangerous that gasoline, it's harder to store and transport safely, and there's the small matter of replacing the entire existing fleet of millions of gas-powered internal combustion engines out there with H2 engines, replacing all the gas stations, distribution channels, addressing all real safety concerns, etc etc.

Add to that, you have to commit to add many more nuclear powerplants to do the H2 generation, else you've gained nothing, emissions-wise.

This is a huge technological and logistical problem, to say the least.