Also I guess they could put a large battery at the charging station so it can take say a steady 200kw from the grid and be able to kick out 1500kw for ten minutes occasionally. That could also charge from cheap off peak electricity.
This is what everyone is already doing, even for relatively small and slow dispensers.
It's simply cheaper to have on-site batteries. It makes installation work with a smaller connection to the grid, and makes it possible to install chargers in more places without upgrading the grid connection.
Energy arbitrage is profitable on its own, so EV charging stations are almost just an excuse to get some land and a grid connection for more batteries.
Not really, all you'd need to do is make a live price ticket that's dependent on congestion and make that available over the network, and economics takes care of the rest.
Supercaps are viable for this sort of short term charge and discharge. The much maligned donut labs is suspected to be a license built Nordic hybrid supercap battery model
