Comment by ben_w
1 day ago
When you're on the moon, why bother with glass? You're surrounded by vacuum and dry rock.
I mean, sure, you can't go over 1022 kV or you get positron-electron pair production from free electrons, but that's still true on your outer surface even with insulation.
Would coaxial HVDC let you go further, because there's no external voltage gradient? I assume so, but mega-scale high-voltage engineering in space combines three hard engineering challenges, so I wouldn't want to speak with confidence.
That said, vacuum is also a fantastic thermal insulator, so perhaps you could do superconducting cables more easily.
I've heard of ballistic conductors*, I wonder if that would scale up… basically the same as the current flowing around a magnetosphere at that scale? https://en.wikipedia.org/wiki/Ring_current
On the other hand, you'd have to make the magnetosphere on the moon first, and "let's use the sky as a wire" sounds like the kind of nonsense you get in the "[Nicola] Tesla: The Lost Inventions" booklet that my mum liked, and therefore I want to discount it preemptively even if I can't say why exactly.
* Not superconducting in the quantum sense, but still no resistance because there's nothing to hit: https://en.wikipedia.org/wiki/Ballistic_conduction
"Just burying your wires in lunar regolith" is another proposed option for long range transmission lines, yes!
We don't know how well that would work in practice though, because there's still a few unknowns about how properties of lunar regolith change across distance.
Some wire applications do require isolation though. For example, motor wiring and other coils.
It would be extremely challenging to make usable coils out of glass coated magnet wire - but it's not like there's oil on the Moon waiting to be made into polymer coatings.
Bury? I was thinking just leave it exposed on the surface. Two chonky lines 2-3 meters apart, double use as a railway.
You make a good point about the other uses of insulation, and ISRU, on the moon.
Would ceramics work for transformers?
I see no reason why they wouldn't.
PCB-based transformers exist, and so do ceramic substrate PCBs. If you combine the two, and find a process to weld the ceramic/glass substrate plates together instead of gluing them together, it could work as a transformer.