“Distributed Generation”
This is dozens — tens of thousands of roof tops and other spaces — tops of shopping malls and parking structures as just two examples — all equipped with their own (smaller) battery banks, and all contributing to “the grid”.
Massive centralized generation and massive battery banks are inefficient, and “ten-ring vulnerable” as targets.
Distributed generation can’t easily be knocked out, as it comes from literally everywhere.
All the technology is now on the shelf to do this. Now. Today. Some residential solar electric systems already are tied in to their local grid and generate more than they use. Right now. Today.
Just make or incentivize many more. (Probably each one would be made a bit larger than they are at the moment, to provide some extra margin.)
Only at extremely high cost.
The ability to tie this all into the grid is not feasible at this time. Perhaps it can be in the future. The problem is in shutting down the grid and bringing it back up. You have to be able to shut down each contributor to the grid and isolate them from the grid. It is very difficult in practice, though it sounds easy.