Hydrogen can be stored in underground caverns and that can be relatively easily scaled to TWh. Electrolysis and fuel cell can get you 70% or so of your electricity back. So it is less efficient then batteries. However there might be a place for hydrogen as seasonal storage. Also the storage makes sense as quite a few processes use hydrogen anyway.

So there is a use case, but right now we mostly should just add renewables and batteries. We are nowhere close to a solar/wind grid, which does actually need seasonal storage. Also grid size helps a lot and there are options such as burning waste.