[Ginden]

> Not sure how it would work once the mercury freezes solid due to lack of sunlight, but I think it's such a beautiful (but maybe impractical) idea :).

Can't you heat it through induction heating? Vacuum is good isolation, so it won't lose heat too fast. Keeping whole pool above -30 °C probably won't require too much energy.

[marcyb5st]

Maybe. I honestly don't know and just read about it quite a while ago and can't remember the details.