4 ms·

Can someone explain how this makes sense economically, isn't it really expensive and lossy to transport electricity such a long distance?

Maakuth 2y ago
You double the voltage and halve the resistance. With longer cables you can invest more in more expensive stuff at the ends to deal with the high voltage.
- left-struck 2y ago
  Resistance stays the same, loss due to resistance goes down. I’m not sure it halves either, it might be better than halving but I’m not sure myself. Edit: Basic power loss formula is P=I^2R, so yes power loss is divided by 4 for a 2x increase in voltage assuming the target power delivered is held constant.
  - adrian_b 2y ago
    Usually the resistance does not stay the same, because it is preferred to use a thinner cable, to reduce its cost. At a given power, double voltage means half current. If the resistance is kept the same, that means 4 times lower losses. If the resistance is doubled by using a thinner cable, that still results in two times lower losses.
    - left-struck 2y ago
      Yeah I agree, I was just pointing out that a wire won’t change resistance due to voltage going up. Of course notwithstanding the wire heating up or something.
      - Maakuth 2y ago
        Thank you for the correction.
dzonga 2y ago
yeah - dumb question from me as well. won't a lot of power be lost during transmission ? What material would they use for the cables at those vast distances to make the numbers work ?
- danielheath 2y ago
  Obligatory jwz post on the topic: https://www.jwz.org/blog/2002/11/engineering-pornography/ https://www.jwz.org/blog/2002/11/engineering-pornography/
  - defrost 2y ago
    22 years old and about three phase AC power on copper cables rather than HVDC power on aluminium cable. But, sure, worth it for the HN=referrer porn JWZ throws up, I guess?
- adrianN 2y ago
  HVDC has reasonable losses over very long distances and solar is extremely cheap. I believe aluminum is used for these cables.
dyauspitr 2y ago
Sun shines for free once the initial infra is set up. Using HVDC at 1100 kV you could transfer up to 65% of the original power which doesn’t sound terrible.
7952 2y ago
There is a price difference between the place you buy the electricity and the place you sell it. That pays for the debt that funded construction. As long as that price difference is high enough it makes financial sense.

Maakuth 2y ago

You double the voltage and halve the resistance. With longer cables you can invest more in more expensive stuff at the ends to deal with the high voltage.

left-struck 2y ago
Resistance stays the same, loss due to resistance goes down. I’m not sure it halves either, it might be better than halving but I’m not sure myself. Edit: Basic power loss formula is P=I^2R, so yes power loss is divided by 4 for a 2x increase in voltage assuming the target power delivered is held constant.
- adrian_b 2y ago
  Usually the resistance does not stay the same, because it is preferred to use a thinner cable, to reduce its cost. At a given power, double voltage means half current. If the resistance is kept the same, that means 4 times lower losses. If the resistance is doubled by using a thinner cable, that still results in two times lower losses.
  - left-struck 2y ago
    Yeah I agree, I was just pointing out that a wire won’t change resistance due to voltage going up. Of course notwithstanding the wire heating up or something.
    - Maakuth 2y ago
      Thank you for the correction.

dzonga 2y ago

yeah - dumb question from me as well. won't a lot of power be lost during transmission ? What material would they use for the cables at those vast distances to make the numbers work ?

danielheath 2y ago
Obligatory jwz post on the topic: https://www.jwz.org/blog/2002/11/engineering-pornography/ https://www.jwz.org/blog/2002/11/engineering-pornography/
- defrost 2y ago
  22 years old and about three phase AC power on copper cables rather than HVDC power on aluminium cable. But, sure, worth it for the HN=referrer porn JWZ throws up, I guess?
adrianN 2y ago
HVDC has reasonable losses over very long distances and solar is extremely cheap. I believe aluminum is used for these cables.

dyauspitr 2y ago

Sun shines for free once the initial infra is set up. Using HVDC at 1100 kV you could transfer up to 65% of the original power which doesn’t sound terrible.

7952 2y ago

There is a price difference between the place you buy the electricity and the place you sell it. That pays for the debt that funded construction. As long as that price difference is high enough it makes financial sense.