That's just me being snarky, but we've been scaling towards this for decades, we just haven't fully gotten there. We can probably solve the technical problems, it seems the main issue to building a fully-connected worldwide power grid is that the cost of scaling that much isn't worth it (yet).
One of the problems with our reliance on oil is that so much comes from an unstable part of the world (although the oil itself contributes to the instability).
Cables under the ocean can be cut by anyone who can get to them with a submarine.
You would be look at cable literally going around the world - at least a good proportion of half way round to be useful. They will be vulnerable one way or another at some point.
Then there is reliability. There have been some fairly bad failures of national power grids. A failure in a global grid would be a lot worse.
Edit: I again made the mistake to comment on a thread dealing with energy x politics. Sorry, I'll try not to do that again. I'm out. It's feral.
What voltage is UHVDC at those numbers? Who is supplying the equipment? Where are the demo installations? What's the cost?
Again, the goal is economic very long distance transfer of electric power. Not a Chinese university research project.
> "HVDC transmission has typically 30-50% less transmission loss than comparable alternating current overhead lines. (For comparison: given 2500 MW transmitted power on 800 km of overhead line, the loss with a conventional 400-kv AC line is 9.4%; with HVDC transmission at 500 kV, it is only 6%, and at 800 kV it is just 2.6%.)" [1]
There are quite a few of UHVDC lines in China, not much in the rest of the world. [0] I don't know what they cost, but maybe you can estimate it based on what they decided to invest over a 10y period.
[0] https://en.wikipedia.org/wiki/Ultra-high-voltage_electricity...
[1] https://web.archive.org/web/20180730045905/https://www.sieme...
As a first guess, one would think it makes more sense to eat 30% loss (so you need 1/0.7=143% installed capacity) than to need 200% capacity plus batteries since it's night about half the time on average. And afaik HVDC is more on the order of ~15% loss
The trick is the "HV" part. China is already running 1100kv on some of their HVDC lines. Transmission losses decrease with the square of voltage, so any increment from that point would be very substantial.
I didn't see any feral responses? Did you not like the ones that pointed out that losses over 800km are <3%, and so your assertion that Ohmic losses are the issue is essentially wrong?