The resistivity of 99.999% aluminium drops by /1000 at 20K without most superconductor drawbacks. nvlpubs.nist.gov
(5MB) p20 - lss.fnal.govShall we chill to 20K the conductors of a 50GW 2000km ±960kV line
to reduce the losses? An ambient temperature (RT) design is there: chemicalforums
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The purer but smaller conductor costs as much metal and oil. At 1/3 the Carnot efficiency, coolers waste 1% of the carried electricity instead of 3% in Al at RT, saving around 0.1G€/year.
Feasible, in absolute terms:
- 50 plies in vacuum insulate the cold Al conductor.
- One more tube separates the vacuum from the oil. The external tube remains.
- Few vertical straps of Ti, duplex steel, glass fibers... hold the conductor.
- Bumps in other directions touch only during seisms.
- The helium in the line equals few hours of worldwide production.
- Assembling vacuum and multilayer insulation in the fields makes trouble.
- Coolant helium must run quickly within the pure Al conductor.
- It takes a cryogenic station every 5km, not pumps and dissipators every 25km.
- If the vacuum is lost, electronics must swiftly protect the line.
- This protection can't easily prolong the operations accepting losses.
- A line for <50GW <2000km favors low-tech even more.
Put together, such a line is far less reliable than the RT design
. But please don't extrapolate to electromagnets or motors.
Also: the RT and 20K designs aren't optimized. A bit more metal or oil at RT might well save as much electricity without all the vacuum and cryogenic fuss.
So the possibility exists, but I put it in sleep mode for now.
Marc Schaefer, aka Enthalpy