> Lower frequency (50/60 Hz) AC is the only really useful choice for transmission on low cost long runs (think 100 km and more). To push high voltage DC on long

> Lower frequency (50/60 Hz) AC is the only really useful choice for transmission on low cost long runs (think 100 km and more). To push high voltage DC on long runs generally means special cables and possibly super conductors. Pushing 60 Hz AC at 230 kV goes over simple cables. I don't think that's true. The point about HVDC is that is is cheaper to do for longer runs than HVAC (that's why they are planning to use HVDC for the new long distance power lines in Germany). Why would you need special cables for HVDC and not for HVAC? DC has less losses than AC for the same current. The only reason AC is used for transmission lines right now is that technology for HVDC wasn't quite ready/cheap enough. It is now.