Such hydrogen storage facilities already exist, actually. But the hydrogen the store is produced via steam reformation which emits carbon. The big issue with hydrogen storage cheaply producing hydrogen without producing CO2.
Inefficiency doesn't matter if you are storing curtailed energy.
If it makes more financial sense and uses less resources to overbuild solar 3x and curtail 60% of the energy than paying for fuel, then you have 2 units of energy you have already paid for spread out over 6-8hrs/day.
As long as using your $300/kw electrolyser at reduced duty cycle is cheaper and less resource intensive than mining and shipping gas, you do it.
