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> Its physicaly impossible to span the pacific and atlantic oceans There are already plans to connect North America and Europe with an undersea power cable. h

> Its physicaly impossible to span the pacific and atlantic oceans There are already plans to connect North America and Europe with an undersea power cable. https://www.offshore-energy.biz/worlds-most-ambitious-subsea-interconnector-igniting-zest-for-clean-power-superhubs-embracing-nato-l-to-reinforce-energy-security-bonds-between-america-and-europe/ https://www.offshore-energy.biz/worlds-most-ambitious-subsea...

Zanfa 2y ago
This is never going to be viable. Even existing short undersea cables are difficult (impossible?) to protect from sabotage, let alone one that would span an ocean.
- ben_w 2y ago
  Longer cables need to be thicker if you want resistance to be fixed. If you want 1Ω then by coincidence a 40,000 km cable has a cross section of almost exactly one square meter. If you're putting a significant fraction of global power through that at any sane voltage, you can't use most cutting tools (or indeed electrical motors) near it because the magnetic field is too strong. China is making enough aluminium that this is a plausible thing they may do as a "belt and road" type project.
  - metalman 2y ago
    Ok, you have the resistance for the cable. Now we need the expansion and contraction due to temperature, and also current, and gravity acting on downward upward sections. Then there is the minor issue of lowering 40km sections to the ocean floor, be a nice boat to work that! Exactly how much arc we gona put in the cable? as we drop it strait down the edge of the continental shelf. And then there are undersea quakes and mega slides, which brings up, exactly what happens when a live wire, that size breaks! When not if, and the gear to fix it, fast. What else, oh ya! kinda cool, but the existing grid already acts like a motor winding that interacts with the earths magnetic field and charged particles coming from the sun. Might want to work that into all of the calcs. Money! There is a huge risk in even starting a full engineering study, due to the very real possibilty of another technology bieng adopted and implimented first.
    - ben_w 2y ago
      A project like this will have many considerations that don't fit into a Hacker News comment. I'd be surprised if a full analysis was less than 200 pages of detailed hard work, including performing actual research to answer questions such as "what exactly is the impact of a surface magnetic field of 0.34 teslas on the local water flow?" and "is marine life impacted by the local magnetic field exceeding Earth's natural field within about 10 km?" I would be surprised if the very slow shift to Earth's poles has any impact, but yes, that too, even if only to rule it out. Temperature, however, isn't one of those questions. Deep water has a near-constant temperature, and even if it didn't, solving for this is already well-studied for continuously welded railways. Likewise, because it's underwater, we can make them in neutrally buoyant sections. Could even make them as two parallel and closely-spaced tracks, so it can built as an underwater railway that delivers its own power and transport during its own construction. > due to the very real possibilty of another technology bieng adopted and implimented first. Not hugely likely, IMO. Long term I can see an argument for doing this as an orbital ring — basically the same idea but make it about π*200km longer so it can be 100km above ground everywhere, spin it so fast it's slightly above orbital speed, magnetically levitate hoops around it that are tethered to the ground and transmit power. Buuuuut orbital rings are only at technology readiness level 2, so nowhere near ready to consider: https://en.wikipedia.org/wiki/Non-rocket_spacelaunch https://en.wikipedia.org/wiki/Non-rocket_spacelaunch https://en.wikipedia.org/wiki/Technology_readiness_level https://en.wikipedia.org/wiki/Technology_readiness_level (For example, an orbital ring has to be build by thickening rather than lengthening to be affordable: it was conceived as a non-rocket launch mechanism, and bootstrapping it by having a thin version lift the material for making it thicker and stronger was a big part of the pricing when it was originally conceived). Whereas a big fat metal wire is at the level of "do sufficient geological and biological surveys to make sure there's an actual route, and accept that the answer may in fact be 'no'" — we *definitely* know how to build a big fat wire (or many smaller wires). We just don't know if we *should*.
  - Zanfa 2y ago
    The tool of choice for cutting undersea cables & pipelines seems to currently be tankers dragging anchors across the seafloor. There's no economically viable protection able to withstand forces like that.
    - ben_w 2y ago
      This is reportedly the largest anchor in the world (not my domain, I wouldn't know): https://www.reddit.com/r/interestingasfuck/comments/hxnyf0/worlds_largest_ship_anchor/?rdt=35505 https://www.reddit.com/r/interestingasfuck/comments/hxnyf0/w... Eyeballing it, the cable I'm suggesting has a metal part about four times that anchor's cross section, let alone the chain's cross section. Even if it was bare metal (in the ocean, which would be madness all by itself), the anchor or the chain would break well before the power cable. With a moderate layer of, say, concrete, that anchor wouldn't even be able to hook onto the cable as the arms don't go out far enough.
hkwerf 2y ago
I'd love to see this realized. However, given the issues we've been having with cables in the Baltic Sea in recent months, this would probably be a huge attack surface in case of any kind of conflict.

Zanfa 2y ago

This is never going to be viable. Even existing short undersea cables are difficult (impossible?) to protect from sabotage, let alone one that would span an ocean.

ben_w 2y ago
Longer cables need to be thicker if you want resistance to be fixed. If you want 1Ω then by coincidence a 40,000 km cable has a cross section of almost exactly one square meter. If you're putting a significant fraction of global power through that at any sane voltage, you can't use most cutting tools (or indeed electrical motors) near it because the magnetic field is too strong. China is making enough aluminium that this is a plausible thing they may do as a "belt and road" type project.
- metalman 2y ago
  Ok, you have the resistance for the cable. Now we need the expansion and contraction due to temperature, and also current, and gravity acting on downward upward sections. Then there is the minor issue of lowering 40km sections to the ocean floor, be a nice boat to work that! Exactly how much arc we gona put in the cable? as we drop it strait down the edge of the continental shelf. And then there are undersea quakes and mega slides, which brings up, exactly what happens when a live wire, that size breaks! When not if, and the gear to fix it, fast. What else, oh ya! kinda cool, but the existing grid already acts like a motor winding that interacts with the earths magnetic field and charged particles coming from the sun. Might want to work that into all of the calcs. Money! There is a huge risk in even starting a full engineering study, due to the very real possibilty of another technology bieng adopted and implimented first.
  - ben_w 2y ago
    A project like this will have many considerations that don't fit into a Hacker News comment. I'd be surprised if a full analysis was less than 200 pages of detailed hard work, including performing actual research to answer questions such as "what exactly is the impact of a surface magnetic field of 0.34 teslas on the local water flow?" and "is marine life impacted by the local magnetic field exceeding Earth's natural field within about 10 km?" I would be surprised if the very slow shift to Earth's poles has any impact, but yes, that too, even if only to rule it out. Temperature, however, isn't one of those questions. Deep water has a near-constant temperature, and even if it didn't, solving for this is already well-studied for continuously welded railways. Likewise, because it's underwater, we can make them in neutrally buoyant sections. Could even make them as two parallel and closely-spaced tracks, so it can built as an underwater railway that delivers its own power and transport during its own construction. > due to the very real possibilty of another technology bieng adopted and implimented first. Not hugely likely, IMO. Long term I can see an argument for doing this as an orbital ring — basically the same idea but make it about π*200km longer so it can be 100km above ground everywhere, spin it so fast it's slightly above orbital speed, magnetically levitate hoops around it that are tethered to the ground and transmit power. Buuuuut orbital rings are only at technology readiness level 2, so nowhere near ready to consider: https://en.wikipedia.org/wiki/Non-rocket_spacelaunch https://en.wikipedia.org/wiki/Non-rocket_spacelaunch https://en.wikipedia.org/wiki/Technology_readiness_level https://en.wikipedia.org/wiki/Technology_readiness_level (For example, an orbital ring has to be build by thickening rather than lengthening to be affordable: it was conceived as a non-rocket launch mechanism, and bootstrapping it by having a thin version lift the material for making it thicker and stronger was a big part of the pricing when it was originally conceived). Whereas a big fat metal wire is at the level of "do sufficient geological and biological surveys to make sure there's an actual route, and accept that the answer may in fact be 'no'" — we *definitely* know how to build a big fat wire (or many smaller wires). We just don't know if we *should*.
- Zanfa 2y ago
  The tool of choice for cutting undersea cables & pipelines seems to currently be tankers dragging anchors across the seafloor. There's no economically viable protection able to withstand forces like that.
  - ben_w 2y ago
    This is reportedly the largest anchor in the world (not my domain, I wouldn't know): https://www.reddit.com/r/interestingasfuck/comments/hxnyf0/worlds_largest_ship_anchor/?rdt=35505 https://www.reddit.com/r/interestingasfuck/comments/hxnyf0/w... Eyeballing it, the cable I'm suggesting has a metal part about four times that anchor's cross section, let alone the chain's cross section. Even if it was bare metal (in the ocean, which would be madness all by itself), the anchor or the chain would break well before the power cable. With a moderate layer of, say, concrete, that anchor wouldn't even be able to hook onto the cable as the arms don't go out far enough.

hkwerf 2y ago

I'd love to see this realized. However, given the issues we've been having with cables in the Baltic Sea in recent months, this would probably be a huge attack surface in case of any kind of conflict.