It's local during normal wind, but not on the rare occasions when one region has practically no wind and another has strong wind. Then it would be best if you can transport multiple gigawatts across distances of thousands of kilometres.

If you've got 1000 5MW windmills way out in the desert (or North Sea), you need a big thick transport network like you do for a nuclear power station.

Actually, no. For that purpose alone, you only need it from the wind farm to inhabited land, where it can be distributed.

Why this should lead to splits among Greens, when it's an engineering issue

Because local opposition to high-voltage power line projects and Greens aren't disjunct groups. No, it's not just an engineering issue.

_{*Lunatic*, n.
One whose delusions are out of fashion.}