There's a whole spectrum of energy storage tech where the tradeoff is efficiency vs cost. At the extreme end of high cost with high efficiency you have magnetic energy storage, then slightly less-efficient but lower cost you have batteries, then in the middle you have things like synthetic methane, cracking hydrogen, and pumping water up-hill, and at the bottom for lowest-cost and lowest-efficiency you have compressed air.

Finding the right balance of overbuilding supply and storage efficiency is going to be a long process.