One energy storage method that's relatively cheap, efficient, and scalable is pumped-storage hydroelectricity. There's a 3 GW plant in Virginia that's been in operation since the 80s[1]! There is ultimately minimal need for FF peakers, or large rare-earth batteries, if governments can execute projects like this.

[1] https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Sta...