Hydrogen will probably fill a niche for seasonal grid energy storage. In general pumped storage > batteries > hydrogen for cost/efficiency, but hydrogen has the advantage that it's cheap to store for weeks or months at a time while pumped storage/batteries are suited only to smoothing out daily or weekly variations in solar and wind output.

It's more useful for getting from 90%/95% to 100% green energy than from 0% - 90% though, and it's more expensive than natural gas performing the same function so we likely won't see it used in anger for a while.