[nl]

> Extremely rare != never, though.

Can you show a single example - anywhere in the world - where this is done at grid scale?

> So it's useful to have a very low capital cost "black swan" backup system. The name of the game here is extremely low capital cost, even at the price of terrible efficiency

I've seen grid scale generators leased as a month-scale solution, so I suppose that counts. That seems more useful than any unproven scheme.