Hydrogen is difficult to store. But it enjoys the square-cube law. If you increase the size of a tank by a factor of 2 in all 3 dimensions, the capacity increases by a factor of 8, but the cost only by a factor of 4.

Hydrogen has some huge advantages over other green options. But, also some huge disadvantages. If you want to diminish the disadvantages, you need to exploit the square-cube law, and that means you need huge scale.

In other words, hydrogen is a non-starter for cars. It has a very low chance of success for buses, but not zero. It could work very well for trains. And it could work extremely well for electricity generation at city scale.

Storage is just part of the problem with hydrogen. The process of generating hydrogen has never been cost-effective. It's just not possible to make hydrogen cheaply right now. Solar energy, on the other hand, gets so cheap that it won't make sense to produce hydrogen with it, then transport it to a city and convert it to electricity. We should just send the electricity directly.

> It could work very well for trains.

Only if you completely ignore overhead wires. Electrifying main rail corridors is a no-brainer, and batteries are more than sufficient for short last-mile spurs.