I suspect the transmission losses would be too great for it to make too much sense.[1] But even if that weren't a problem, well, politics.
[1] https://en.wikipedia.org/wiki/Electric_power_transmission#Lo...
[1] https://en.wikipedia.org/wiki/Electric_power_transmission#Lo...
I know that the grids - as they stand right now - must balance generation and consumption. Would a large outage (or large spike) in any given part of the interconnected grids be able to take out all of it?
Nine regional interconnected grids are already functioning within China, so the technical feasibility of transmitting electricity across long distances at high voltages has already been proven."As of 1980, the longest cost-effective distance for direct-current transmission was determined to be 7,000 km (4,300 mi). For alternating current it was 4,000 km (2,500 mi), though all transmission lines in use today are substantially shorter than this." [It's unclear when "today" means, or at what voltage these lines were running. But the 1000KV range this renewable grid is running is pretty typical, and, is in the ballpark of these quoted distances.]
For reference, the circumference of earth is about 40,000km (as parent was pondering). The thing is, transformers and wire haven't exactly changed much since 1980. So until we can figure out room-temperature super conductivity, or a more efficient way of massively scaling up/down voltages than transformers, I'm inclined to believe the situation hasn't changed much since then. Then again, I'd love to be proved wrong.