[ncmncm]

Batteries are also chemical storage, but I guess you mean synthetic fuels. Their cheap tankage, easy transportability, and ready sale value forgive a great deal of inefficiency. If not drawn down every night, efficiency hardly matters. Overnight storage wants efficiency and unlimited cycles. But transmission lines will probably end up preferred where available.

Buoyancy storage, where deep water is ready to hand, and mineshaft storage, where you have one, will be very, very cheap and efficient. Transmission lines mean such conveniences need not be especially nearby. But Europe is absolutely perforated with mineshafts.

Besides smoothing, there is very little use for storage yet, because we haven't got enough to charge it from. Charging storage from NG turbines would be worse than silly. So, we build out generating capacity first, then storage.