There’s a ton of options there besides hydrogen. Flow batteries are far more efficient than hydrogen, and there’s no particular barrier to mass production at this point. Then there’s anything from flywheels, other battery chemistries that are too heavy for EVs, or just pumping water uphill.
We need options there today. We want to be on 80% renewables by 2030 in industrialized countries, and that will require some kind of storage solution. Fortunately, we already have quite a few.