On Jun/11/2020 at 19:45, David Spain wrote :
On 2020-06-11 7:21 PM, Alain Fournier wrote:

That 1500 km line is *very* heavy. You want to use the best strength
to weight ratio, you don't want to add the constraint that the
material is also a good electrical conductor.


Alain Fournier

Ahh but for the near-miraculous carbon nanotube in the 'armchair'
configuration (acting as a metallic nanotube) it is! From Wikipedia:

"In theory, metallic nanotubes can carry an electric current density of
4 × 10**9 A/cm2, which is more than 1,000 times greater than those of
metals such as copper..."

Dave


Ref cites:

https://en.wikipedia.org/wiki/Carbon...e#cite_note-55

https://doi.org/10.1103%2FPhysRevLett.68.631

http://resolver.tudelft.nl/uuid:4e58...2-aabcc9eaad35

https://doi.org/10.1038%2Fnnano.2007.89

Yes but carbon nanotube aren't a material. Until someone figures out how
to make a useable material out of them, you can't make a cable with
them. Just aligning lots of nanotubes one next to the other doesn't make
a strong cable. You need to get the nanotubes to hold together. And
if/when someone does figure out how to make a useable material out of
nanotubes, it isn't sure that such a material will still be highly
conductive. It might be, in which case yes running electricity in the
cable might make sense.


Alain Fournier