Sodium-ion batteries appear promising. Like, the energy density by weight of the current market offerings is absolutely too low to be useful for vehicles, but there's hope that can be improved in a relatively short timescale. Prices should be pretty good when factories finish tooling up, and most chemistries use no rare earth metals. Current densities seem great for grid storage, which is where hydrogen has the most potential right now (imo).

I still like the idea of hydrogen for some forms of transportation (freight trains, container ships, possibly aircraft if energy density could be increased or aircraft weight decreased somehow) and as a strategic emergency energy reserve. It'd be great to have more grid resilience as the environment continues to decay. I just worry about the energy costs that come with transporting hydrogen. Pipelines seem like they'd be challenging, and trucking it around seems a bit wasteful. In-situ generation would be ideal if power and water are available and hydrolysis can be made more efficient and compact, but that's not possible everywhere.

I dunno. I'm glad it's not my job to figure out the actual energy cost of everything, but I'm really hoping grid-scale sodium-ion batteries will become a reality sooner rather than later.