That was about the amount in both cases. Slightly more in the no-hydrogen case than otherwise. Hydrogen contributed only marginally.

Yes, it's a lot of batteries. So what? It's not like the current battery production is some firm limit. If anything, the very large future demand ensures batteries will be driven down their experience curve, so the cost will be even lower than assumed.

The world spends something like $10T per year on energy. Any replacement energy system is going to be a big thing.

You need to make an argument that is more than you expressing fear of large numbers.