4 ms·

Impressive piece of work, first time I’ve heard of this. I had heard that tunnels were a good first step for rolling out super conducting cables, but that does

by zeristor 10mo ago

Impressive piece of work, first time I’ve heard of this. I had heard that tunnels were a good first step for rolling out super conducting cables, but that doesn’t seem to be a thing. Superconducting cables have progressed a lot. I’m assuming that setting up a cryogenic system to keep cables cool enough, in a confined space wasn’t thought to be worth it. The tunnels look tight enough, and boiling liquid nitrogen from a leak could cause asphyxiation I imagine.

lukan 10mo ago
"I had heard that tunnels were a good first step for rolling out super conducting cables, but that doesn’t seem to be a thing." Yeah tunnels underground would be better for superconducting cables, but it is indeed not really a thing as the cooling and installing and maintainance would be waaaay more expensive, than just using higher voltage. Or if one really cares about the loss, use direct current - but we are talking aber very small distances here. If superconducting would be easy, we likely just would have fusion plants everywhere with no need for transporting electricity long distances.
- ferfumarma 10mo ago
  > Or if one really cares about the loss, use direct current I thought direct current had higher transmission losses vs AC
  - tallowen 10mo ago
    AC has higher losses over a transmission wire because of the changing magnetic field that it induces which creates losses.
    - HPsquared 10mo ago
      There's a cool effect where if you hold a fluorescent tube under a high voltage power line, capacitive coupling from the varying electric field causes it to light up. Some energy is continually leaking out via this route, the tube just reveals it. (Magnetic induction too) https://youtu.be/0D50Dcvzkr4 https://youtu.be/0D50Dcvzkr4
      - afandian 10mo ago
        You can feel it yourself if you have a piece of metal, like a bike.
  - LargoLasskhyfv 10mo ago
    Not if it's really high direct current, like https://en.wikipedia.org/wiki/High-voltage_direct_current https://en.wikipedia.org/wiki/High-voltage_direct_current Problem is they need these https://en.wikipedia.org/wiki/HVDC_converter https://en.wikipedia.org/wiki/HVDC_converter , for these https://en.wikipedia.org/wiki/HVDC_converter_station https://en.wikipedia.org/wiki/HVDC_converter_station which are expensive. So it depends on circumstances, how and when its economically feasible to use HVDC, or not.
  - teo_zero 10mo ago
    Tesla vs. Edison is back! :)
mr_toad 10mo ago
The tunnels are just for ease of maintenance. https://en.wikipedia.org/wiki/London_Power_Tunnels https://en.wikipedia.org/wiki/London_Power_Tunnels
- locknitpicker 10mo ago
  > The tunnels are just for ease of maintenance. The fact that the tunnels are 50 meter underground leads me to wonder if their main requirement comes from national security needs.
  - defrost 10mo ago
    London underground is prime real estate - to find a level and avoid * the recent new massive and extensive sewer tunnels, * the secret basement extensions of the ultra rich, multi story archival storage, vaults, etc, * the new underground tunnels (rail / subway for US readers), * old roman and other buried but still 'conserved' architecture, * crypts, graves, plague pits, * WWII UXB's etc. etc is a hell of a 3D needle to thread - there's > 2,000 years of urban layering in that small area.
    - OJFord 10mo ago
      And unmapped (and changing, inadvertently diverted) rivers
  - ant6n 10mo ago
    There’s Probably simply too much city in the way on higher levels. If you wanna knock out the grid, hit the substations and power plants.
  - deleted 10mo ago
    [deleted]
- everfrustrated 10mo ago
  The way the regulator regulates capital returns incentivises overspending on lavish infrastructure works as a way to return more profits back to the shareholders.
zeristor 10mo ago
From Gridlock to Grid Power: The Promise of Superconducting Cables https://ee.eng.cam.ac.uk/index.php/2025/09/22/from-gridlock-to-grid-power-the-promise-of-superconducting-cables-in-the-uk/ https://ee.eng.cam.ac.uk/index.php/2025/09/22/from-gridlock-... An interesting article, I’ll download the IoP report and maybe read it. But it talks about doing the hard work to improve the Technological Readiness Level from 7 to 9. Although these cables need rare earths so might be problematic.
BrtByte 10mo ago
I think tunnels like this are more about future-proofing access than betting on a specific technology
quickthrowman 10mo ago
> Superconducting cables have progressed a lot. I’m assuming that setting up a cryogenic system to keep cables cool enough, in a confined space wasn’t thought to be worth it. Yeah, the cost isn’t worth it. Buying two transformers to step up the voltage on one end and step down the voltage at the other end is going to be several orders of magnitude cheaper than actively cooling cables to 20K for their entire length.
schainks 10mo ago
Indeed, the cooling infra needed for cryo makes the price per watt go up by unreasonable amounts per unit length. Also your cryo liquid should ideally be something that doesn't do the following things: 1. Leaks — shouldn't cause asphyxiation risk to humans who need to fix the leak. 2. Broken cable due to disaster – coolant doesn't turn into explosives when in contact with high voltage high current electricity. However, UHV DC electricity in tunnels could be financially attractive and safe if you can cool the tunnels properly (no superconducting cryo)
- quickthrowman 10mo ago
  > However, UHV DC electricity in tunnels could be financially attractive and safe if you can cool the tunnels properly (no superconducting cryo) AC transformers are so much cheaper than DC converter stations that I don’t think this will ever be true. At the distances HVDC has a distinct advantage at, you wouldn’t be building tunnels. HVDC is mostly useful for grid ties between unsynchronized grids.

lukan 10mo ago

"I had heard that tunnels were a good first step for rolling out super conducting cables, but that doesn’t seem to be a thing." Yeah tunnels underground would be better for superconducting cables, but it is indeed not really a thing as the cooling and installing and maintainance would be waaaay more expensive, than just using higher voltage. Or if one really cares about the loss, use direct current - but we are talking aber very small distances here. If superconducting would be easy, we likely just would have fusion plants everywhere with no need for transporting electricity long distances.

ferfumarma 10mo ago
> Or if one really cares about the loss, use direct current I thought direct current had higher transmission losses vs AC
- tallowen 10mo ago
  AC has higher losses over a transmission wire because of the changing magnetic field that it induces which creates losses.
  - HPsquared 10mo ago
    There's a cool effect where if you hold a fluorescent tube under a high voltage power line, capacitive coupling from the varying electric field causes it to light up. Some energy is continually leaking out via this route, the tube just reveals it. (Magnetic induction too) https://youtu.be/0D50Dcvzkr4 https://youtu.be/0D50Dcvzkr4
    - afandian 10mo ago
      You can feel it yourself if you have a piece of metal, like a bike.
- LargoLasskhyfv 10mo ago
  Not if it's really high direct current, like https://en.wikipedia.org/wiki/High-voltage_direct_current https://en.wikipedia.org/wiki/High-voltage_direct_current Problem is they need these https://en.wikipedia.org/wiki/HVDC_converter https://en.wikipedia.org/wiki/HVDC_converter , for these https://en.wikipedia.org/wiki/HVDC_converter_station https://en.wikipedia.org/wiki/HVDC_converter_station which are expensive. So it depends on circumstances, how and when its economically feasible to use HVDC, or not.
- teo_zero 10mo ago
  Tesla vs. Edison is back! :)

mr_toad 10mo ago

The tunnels are just for ease of maintenance. https://en.wikipedia.org/wiki/London_Power_Tunnels https://en.wikipedia.org/wiki/London_Power_Tunnels

locknitpicker 10mo ago
> The tunnels are just for ease of maintenance. The fact that the tunnels are 50 meter underground leads me to wonder if their main requirement comes from national security needs.
- defrost 10mo ago
  London underground is prime real estate - to find a level and avoid * the recent new massive and extensive sewer tunnels, * the secret basement extensions of the ultra rich, multi story archival storage, vaults, etc, * the new underground tunnels (rail / subway for US readers), * old roman and other buried but still 'conserved' architecture, * crypts, graves, plague pits, * WWII UXB's etc. etc is a hell of a 3D needle to thread - there's > 2,000 years of urban layering in that small area.
  - OJFord 10mo ago
    And unmapped (and changing, inadvertently diverted) rivers
- ant6n 10mo ago
  There’s Probably simply too much city in the way on higher levels. If you wanna knock out the grid, hit the substations and power plants.
- deleted 10mo ago
  [deleted]
everfrustrated 10mo ago
The way the regulator regulates capital returns incentivises overspending on lavish infrastructure works as a way to return more profits back to the shareholders.

zeristor 10mo ago

From Gridlock to Grid Power: The Promise of Superconducting Cables https://ee.eng.cam.ac.uk/index.php/2025/09/22/from-gridlock-to-grid-power-the-promise-of-superconducting-cables-in-the-uk/ https://ee.eng.cam.ac.uk/index.php/2025/09/22/from-gridlock-... An interesting article, I’ll download the IoP report and maybe read it. But it talks about doing the hard work to improve the Technological Readiness Level from 7 to 9. Although these cables need rare earths so might be problematic.

BrtByte 10mo ago

I think tunnels like this are more about future-proofing access than betting on a specific technology

quickthrowman 10mo ago

> Superconducting cables have progressed a lot. I’m assuming that setting up a cryogenic system to keep cables cool enough, in a confined space wasn’t thought to be worth it. Yeah, the cost isn’t worth it. Buying two transformers to step up the voltage on one end and step down the voltage at the other end is going to be several orders of magnitude cheaper than actively cooling cables to 20K for their entire length.

schainks 10mo ago

Indeed, the cooling infra needed for cryo makes the price per watt go up by unreasonable amounts per unit length. Also your cryo liquid should ideally be something that doesn't do the following things: 1. Leaks — shouldn't cause asphyxiation risk to humans who need to fix the leak. 2. Broken cable due to disaster – coolant doesn't turn into explosives when in contact with high voltage high current electricity. However, UHV DC electricity in tunnels could be financially attractive and safe if you can cool the tunnels properly (no superconducting cryo)

quickthrowman 10mo ago
> However, UHV DC electricity in tunnels could be financially attractive and safe if you can cool the tunnels properly (no superconducting cryo) AC transformers are so much cheaper than DC converter stations that I don’t think this will ever be true. At the distances HVDC has a distinct advantage at, you wouldn’t be building tunnels. HVDC is mostly useful for grid ties between unsynchronized grids.