I never even mentioned AC until you brought it up. Are you conflating discussions or something? Your reply said, "Did I miss this tremendous development in science that allows us to store electricity?" Yes, batteries allow for energy storage. Maybe your response should have been more specific, yes?
AC can drive electric motors, right? Flywheel energy storage. Yes I know the difference between AC and DC, thanks.
Right, "large" is vague. Pumped-storage hydropower would be large. Large-scale battery technology is just starting to be deployed, so extrapolate into the future. The limitation is in the lithium supply.
No I never suggested that particular storage mechanism should be used to power LA. That's a strawman argument bordering on ludicrous. You can arbitrarily choose a counter-example by picking a large enough target pool, so it's a useless point.