archae86:
It was NEVER true that DC was inefficient for transmission at the same voltage--what was true was that it was vastly more expensive to do voltage conversion for DC. Modern power electronics (and, no, this is not Moore's law in action) have lowered conversion costs (both from one DC voltage to another, and AC to DC and reverse), and DC is becoming more common in serious long-distance applications...
Very true, something I did not address in my earlier post. The first I heard of DC transmission was a bi-directional link between the UK and the continent, 30-40 years ago. Did this ever come to pass? The incentive claimed was peak load stagger, when one region had excess capacity, the other had excess demand.