[londons_explore]

They are of the same order of magnitude...

Big high voltage transmission lines lose ~200 watts per meter in resistive losses when under full load.

The electrical energy to keep something 1 meter long at liquid nitrogen temperatures is also ~200 watts, assuming 8 inches of insulation.

The resistive losses go down with the square of the power transmitted - so they fall to zero rapidly when not under full load. Cooling losses stay approximately constant.

Therefore, I suspect a liquid nitrogen cooled superconducting cable wouldn't work out financially.

Math only correct to an order of magnitude...

[zardo]

The actual trade-off would have to be far better insulation e.g. double wall vacuum insulated stainless pipe. With much higher upfront costs.

[rini17]

So now you have two problems. Not only liquid nitrogen but also vacuum :)

[themeiguoren]

This is my own ignorance, but what determines the power carrying capacity of a wire besides melting from the resistance? Could you transmit a lot more wattage through that same line when superconducting?