It is great to see Reuters bring to the public the esoteric but very important topic of High Voltage DC Power Transmission. This is the technology that could be taking power from the Great Plains to the coasts. I think that they underestimate the amount of grid expansion that is going to happen worldwide. Very troubling that the US does not have a dog in this hunt!
“Do you want to remap with secondary farm roads or with highways? The supergrid is this highway,” Poux-Guillaume said.”
The Atlantic Wind Connection is an example of an ambitious plan for HVDC power transmission which would provide access to windpower up and down the Eastern Seaboard.
The Grain Belt Express Clean Line HVDC is a land based project that is being developed to bring interior wind from the Great Plains East.
Lots more about HVDC with references including information about efficiency HERE
Wikipedia provides a good introduction to HVDC. However, not so much on how it is relevant to renewables, though there is a little bit towards the end.
Other resources include this IEEE Spectrum article on HVDC advances,
HVAC – Here is an article about expanding portions of the grid with HVAC and the difference between HVAC 345kV and 765kV