[nthj]

> we need to store enough energy to power the whole country for at least 2 weeks before we can get rid of fossil fuels.

Maybe this is self-obvious, but "get rid of" seems to be carrying a lot of weight in that statement. I personally am not offended or concerned by keeping natural gas generators around for decades, even, as insurance for catastrophic disasters, if in practice they're unused 99% of the time because storage infrastructure has reached 24 hour capacity. We reach diminishing returns on increased storage.