[nl]

It's extremely rare to need to store months of energy at grid scale.

Wind power works really well in winter as well as summer. In many places solar works sufficiently well in winter given the lower consumption levels due to lower air conditioning usage.

[pfdietz]

Extremely rare != never, though. 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 (which is ok since this system will almost never be running.) Hydrogen stored underground and burned in turbines could do it.

[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.

[goodcanadian]

This is true in a lot of places. However, in the places that I am most familiar with, energy consumption is MUCH higher in the winter due to heating . . .

This may be where the international HVDC lines come in (that a sibling comment of yours mentioned), I suppose.

[distances]

I don't think any country in the north would rely on imported energy for winter survival. I think pretty much every country even in EU counts that critical enough to warrant domestic capacity.

[goodcanadian]

Which is why essentially every country in Europe relies on Russia for gas supplies?

I suspect most of Northern Europe would be happier importing energy from Southern Europe or even North Africa than relying on Russia as they currently do.