After many false starts, hydrogen power might now bear fruit
Hydrogen has an efficiency problem. You need to convert other forms of energy to hydrogen at a loss. Then you need to store it and transport it, which is costly and may impose quite some energy cost for cooling or compression. Then you need to convert it back to electricity, also at a loss. If you start at electricity, the electrical grid and batteries would be much more efficient. If you start at oil or gas, you could use convention ICEs and get comparable overall efficiencies. For them transport and delivery is a solved problem.Hydrogen fuel cells are clean where you use them. But so are batteries. Inner cities could be kept cleaner using either. Inner city traffic is mostly short range, so batteries are at an advantage.Batteries have a rare earth problem. But so do Hydrogen fuel cells. There is work to reduce it for both technologies.Hydrogen fuel cells have a problem with varying loads. You would use additional batteries in cars to supply peak demand when accelerating or store braking energy. For comparable weight, range, and price you could replace all hydrogen technology with more batteries. Those bigger batteries would also wear out slower because the power demand per cell is lower.So, when would hydrogen make sense? I think only if you don't care for efficiency. When you have so much electrical power that it costs you nothing and is available at least a few hours every night. Hydrogen would do well in a combination with large scale nuclear fission/fusion. It could take decades until we get there if we ever go that route.I see that, as batteries become less and less expensive, the niche where Hydrogen could have good advantage is getting smaller and smaller. However you twist and turn it, either oil&gas or batteries have the advantage.