As mentioned, you can't do it with batteries.

To capture the 1.21 GW from a lightening strike requires a flux capacitor.

As far as I know, we have yet to figure out how to capture power from a lightning strike. There is a lot of energy there, but it's static electricity which is completely different from what any grid runs on.

You'd probably use some kind of capacitor

To capture it? Quite a few I'd imagine. The energy you could collect though from one hit is quite low.