That all sounds like politics? If so, that's a point we agree on :)

None of that seems like physical issues, despite you mentioning that on the first paragraph.

> For the Russia example, in the situations Russia wouldn’t want to cut it - the US and China would love to! Or have a proxy do it for them.

If they have alternatives, otherwise they're all in the same boat whose name is "interdependence".

China's also the only country that seems to have any even slightly serious interest in attempting to build anything close to such a grid in the first place, as part of their own soft-power projection, and are the only country producing enough aluminium to attempt it anyway — half of all current global production is factories they switched on since 2006: https://international-aluminium.org/statistics/primary-alumi...

Nobody else but China will bother in the foreseeable future, and even China might not. (Which is yet another rephrasing of the same point I've been making throughout).

> And if Russia has enough battery storage to last a week or two (minimum to outlast a storm; and also more than adequate to deal with daily insolation variation), they don’t have much of a need for these cables either, correct? At least most of the time.

Sure, but a week of storage is at least* 14 times more expensive than overnight storage.

If you see your enemies building up a lot of storage without any clear reason, you know Something Is Up, just like if you see them amassing tanks on your border.

If they have a clear reason, "there is no power grid in the first place" being one, then it's harder to know they're doing something odd.

> And if they do have adequate alternatives, then why is it a big deal to have the cable? What does it actually offer?

Lower price.

I'm expecting batteries to get cheaper, but the current price is in the order of $100/kWh capacity, if they last 1000 cycles that's $100/MWh delivered*. If you have to size your battery packs for long-term use, be it Dunkelflaute or seasonal or military shenanigans, you don't get to discount that, it's what it is; but if you're only using it for emergencies, then those batteries don't wear down as fast just because you don't go through those cycles so often — how much depends on the duration and frequency of the emergency, and also how well your batteries cope whatever they do in a non-emergency condition.

A global mega-project is obviously going to be more expensive than the mere material costs; even the opportunity cost of what else they could do with the same resources is a huge question, and why it's heavily in the "politics and economics" domain rather than the mere physicality.

But the mere physicality that I'm openly and explicitly and repeatedly acknowledging comes with additional political difficulties**, that's a few hundred billion for a thing that lasts 75-120 years based on other examples; it would carry in the order of a terawatt continuously, 24/7, for about 1/250th - 1/440th the price of batteries: https://www.wolframalpha.com/input?i=%28239+billion+USD%29+%...

* Night has significantly lower demand: you've got 50% power demand, that's 1/3rd of the total daily energy demand from draining batteries, so they only add $33/MWh to the deliverable cost.

** It's frustrating that this combination is still ignored so often when I mention this physical possibility; how can I possibly be clearer that I know that all the other stuff besides actually building it is hard?