[dreamcompiler]

The difference is not really about distance. Your link is accurate though.

High voltage is always more efficient for power transmission over any distance than low voltage, regardless of AC vs DC, in any conductor whose resistance is not zero. This is because of I^2R losses.

For any specified value of [high] voltage and a specified wire and a specified distance, DC will be slightly more efficient than AC, for other reasons like skin effect.

But we don't want high voltage in our homes, so changing voltage down for consumption and up for transmission is essential.

Voltage changing was basically impossible with DC back when the grid was invented 120 years ago. But it was easy with AC. So our grid is AC.

Today we have power semiconductors which allow us to switch DC voltages easily. If the entire grid were being invented today -- from scratch -- it would be entirely DC.

[flangola7]

Wikipedia tells me HVDC runs at 100s of kilovolts. What kind of semiconductor can handle that without promptly turning into plasma?

[cwillu]

https://en.wikipedia.org/wiki/File:Pole_2_Thyristor_Valve.jp...

My understanding is that the semi's are stacked so that any individual switch only sees a voltage it can handle, with safeguards to cut off the whole mess on failure.

[dreamcompiler]

Big ones, usually made of silicon carbide.