> Storing hydrogen is insanely difficult. Doing it at grid scale has to have astronomical costs

Surprisingly, storing hydrogen at grid scale is the only time it's relatively easy to do so.

Hydrogen can be stored in salt caverns, and those are already used extensively for long-term natural gas storage, so the infrastructure for grid-scale hydrogen storage is more-or-less already there (some piping would need to be upgraded).

Small-scale use (like cars) doesn't make economic or logistical sense, but large-scale use (like seasonal electricity storage or green steel manufacturing) is looking fairly reasonable.