>>11356367There is a way to ask that nicely.
It's been a while, but here is as I remember it:
Loses in high voltage AC wires in air or ground are mostly due to resistance of the wire itself. Not the medium around it, because Impedance (summarily name for Capacitance / Inductivity) of air and ground is negligible. Therefore it does not matter all that much if it's AC or DC. Therefore, since the "conversion" between different voltages is considerably easier with AC, that's why it's predominantly used.
However, once you put the wire in water, the impedance starts playing the more important part in calculating loses, up to a point where having a "frequency of 0Hz" as in DC has an impact. Therefore the savings in loses justify considerably more expensive conversion equipment required on either side.
To put this in perspective, you can literally transform 230kV line into 230V line with a piece of coiled wire. Yeah. That's essentially what transformer is.
To do the same, you need an equivalent of Switched-mode power supply, because no, resistance-based Voltage splitter is really not a good solution, thanks to the incredible losses it introduces.
