1. Storage: Pumped hydro and/or peaker batteries.
Hydro: mountains with lakes at both the top and bottom are in very short supply.
Peaker Batteries: I think a giant slice of the next 20 years of battery research will be centered on making batteries that don't have Lithium (and to a lesser extent Cobalt, Nickel, and a few other things) in them. Lithium-Iron-Phosphate was a great advancement in cheaper (although a bit worse in some categories besides energy density, like cold weather response) batteries, but we really need good rechargable batteries that don't use Lithium, yet avoid nightmares like NiCad and Lead-Acid. (for reasons of 'memory' degradation and Pb poison, respectively)
I don't think there's all that many people that appreciate that Lithium wasn't chosen for battery research because it's the cheapest and best thing to make batteries out of, but because it's a pretty good thing to make LIGHTWEIGHT batteries out of. Low weight is great for things people carry around, but the way EV builders are pac-manning up Lithium from mines, it's surprising it hasn't gone up in price like a rocket. Time to diversify, particularly for batteries intended to sit in the middle of nowhere (next to a power plant, or grid interconnect line, of course).
Supposedly BYD is selling Sodium based batteries in their cars, but it's so new I haven't heard anything as far as reliability, although it seems to be at least somewhat functional and pretty inexpensive. If there's one thing this planet has, it's plenty of Sodium, available worldwide, with a few even higher waste sodium sources could be tapped, maybe like water purification discharge. A couple of salt water lakes that could use less metal in them, come to think.
I'd really love to hear Telsa announce Sodium batteries, but I haven't heard enough to know if it's just the money arrangements with whoever aren't in place, the fabrication arrangements aren't in place, or there's a long term suitability reason.