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Comment by hnarn | Hacker News Reader

This might be a stupid question, but is it implicit that these "submarine cables" are all fiber cables? If so, are they of similar or very different bandwidths? I would think there are cables of differing ages that are used for different things, or are all non-fiber cables taken out of service long ago, or are they just not included on the map?

Also, the "Polar Express" cable on that map is fascinating, but it seems like it's not planned to be completed until 2026.[1]

[1]: https://www.submarinenetworks.com/en/systems/asia-europe-afr...

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Copper communications cable were in use from 1850 until the 1980s, when they were replaced one by one with fiber. Almost all the copper cables ever laid are still in the depths of the ocean, as it's not worth salvaging them except near shore. A few of the more recent copper cables are still operational, but they are used only for scientific research.

That’s true for communication cables though, so what about cables for electricity? That’s mostly what my original comment was about, that the title seems to imply any submarine cable is automatically a data cable.

Why would you send electricity across the ocean? You can generate it locally on both sides.

Not all of these lines go across the ocean. If you're trying to move power between São Paolo and Beunos Aries, it might be cheaper to lay a sea cable than to deal with all the terrain, land rights and borders involved in an overland route.

Not all submarine cables cross oceans.

Some seem to be for redundancy, some bring power to municipalities (i.e. island cities) with limited power production capacity. There’s a list here https://en.m.wikipedia.org/wiki/Submarine_power_cable

There is (if it has not been scuppered by brexit) Icelink, a project to connect Iceland to the UK. The rationale, as usual, is mismatched supply and demand, where the supply is green geothermal power.

https://askjaenergy.com/2018/04/17/icelink-in-operation-by-2...

The idea of connecting solar farms in the Sahara to Europe under the Mediterranean is also perennially in the air, with the same rationale as Icelink.

Electricity is just that much cheaper in some places than others. Bauxite is shipped far across the ocean to places with cheap electricity for the energy-intensive process of refining it into aluminum. Sometimes it makes more sense to ship the electricity instead. Here in Canada, I pay like 20% of what the Japanese pay and 10% what the Danish pay for electricity. If we could figure out a way to export our hydroelectric wealth to regions like Europe and Asia, it could help climate change. High-temperature superconductors don't get enough research, IMO.

they do get enough research, unfortunately they are some of the most complex physical systems and we still haven’t figured out why exactly they superconduct (i used to work on this).

There are high voltage submarine cables for electrical power - these are used to cross rivers and lakes, for example. International cables, like the ones between the UK and the European mainland, are used for load balancing. As it's difficult technically to transmit electrical power over a subsea cable (and exponentially more difficult at the length increases), these cables have limited application. There's over a million kilometers (~600,000 miles) of fiber optic communications cable around the world right now, and perhaps a thousand or so miles of power cable, so "submarine cable" without any qualifier almost always refers to communications cables.

https://en.wikipedia.org/wiki/Submarine_power_cable#Operatio...

I strongly doubt there are any non-fiber submarine cables. Fiber's main strength is range; trying to run signals over electrical conductors over hundred-km-plus distances is not cost-effective and hasn't been for decades.

(It's been done historically, but with very heavy cables, very high endpoint power levels, lots of repeaters, and really poor throughput.)

> I strongly doubt there are any non-fiber submarine cables.

I strongly doubt electrical cables are fiber cables for example :-)

On a more serious note, I was thinking that there are perhaps copper cables used for telephone communications that are still used simply because they haven't yet failed, but I assume fiber has perhaps been the standard for backbones long before it became something people have in their homes.

Wouldn't it make sense for some electrical cables to have some fiber in them? When you're already laying them, you could get two services for the price of one.

I suppose it would, I guess I'm just wondering for how long fiber cables have been the standard, and if there are any operational cables from the time before that. I'm pretty sure there are plenty of cables dedicated for one purpose (e.g. electricity only) that do not contain fiber simply because there wasn't a need or requirement when it was planned.

edit: Here's an example:

> The world record from 1994, for the longest HVDC cable with the highest capacity, was equalled in 2000 with the successful completion of the Swedish-Polish HVDC transmission link between Sweden and Poland:

> 1. Stretching over 250 km, it is one of the two longest submarine HVDC cables ever laid.

> 2. At 600 MW, the cable is one of the most powerful HVDC cables in commercial operation.

> 3. At 450 kV DC, this cable together with the cable between Sweden and Germany, has the highest voltage rating of all existing submarine HVDC cables.

This cable doesn't seem to have any other purpose than transferring electricity, and it was installed "only" 21 years ago.

I highly doubt it's cost-effective. These things are complicated and have specialized equipment. The endpoints also very different for data and electricity.

I'm certainly no expert here but I'm guessing it doesn't make sense for two reasons:

1) Modern communications fibers are complicated (https://en.wikipedia.org/wiki/Submarine_communications_cable [1]) and presumably expensive so speculatively adding them to power cables would likely be a pricey endeavor.

2) AFAIK most submarine cables are systems — e.g. a ring the connects various places so that there are two paths between points — so trying to plan one to that co-opts existing bits of fiber piggy-backed on power probably wouldn't be easy. Also you'd have the issue of dealing with different generations of fiber, standards, etc.

[1] On reading this it turns out that modern fibers actually carry power as well so that repeaters en route can be powered.

In almost all conceivable contexts, no. If you've ever done any work with electrical code, you are familiar with the spacing requirements between electrical conduit and data wires to prevent magnetic interference: at least a foot apart, and perpendicular crossings if crossings are necessary. The voltage on underwater electrical cables are quite high, as is the bandwidth on underwater data cables, so you definitely can't have them mixing if you want anything near optimum results on data transfer.

he was asking about fiber which is not subject to electro-magnetic interference

Even setting that aside Undersea power is DC

Optical fibres are also pretty good sensors so it's not unlikely that some fibres are added just for sensing purposes (they are eput into lots of bridges and other things for example). That said it highly depends on the length of your electrical cables if putting in fibre for communications makes sense. Typically (grossly simplified) you need optical amplifiers when you go significantly over transmission distances of 100km so they need power supplies, take up quite a bit of space etc..

Already a thing, one of the high voltage power cables to Tasmania also has singlemode fiber in it. Not uncommon.

Shown on the map as "basslink". you can find it on the southern side of australia, it's the easternmost tiny little line crossing INDIGO central.

500 MW electricity interconnector + bonus 12 core fire cable

https://en.wikipedia.org/wiki/Basslink#Basslink_Telecoms

They probably already had some inside but not for general use, but to exchange data between the two ends of the cable. Modern power grid is smart, and it has data connection along side power, they do that also on overhead power lines (the upper cable beside the three phases serves as a protectoin from lightning strikes but also has a fiber inside). In practice the power network also has a completely isolated LAN (for obvious security reasons) to manage the whole infrastructure. At least in my country it's done like that.

Doesn't a lot of these cables pre-date fiber? They had these in WWII. I remember the Gilligan's Island episode where the cable washes up in the lagoon and the professor was able to connect up a phone so they call around the world -- of course Gilligan screws it all up at the end.

Until the 1950s, transatlantic communication was done with radio. Then it was copper until the 80s

But weren't the British Empire's undersea telegraph lines all copper? They lay the first transatlantic cable in 1858, connecting Ireland and Newfoundland. By 1911 their worldwide undersea network was completed, with so much redundancy that 49 cuts would have been necessary to isolate the United Kingdom from its empire. https://en.m.wikipedia.org/wiki/All_Red_Line

None of that stuff is still in service. (At least not telecom.) They require periodic, expensive maintenance, and fiber outclasses copper for long-distance signatures to a much greater degree than for the last-mile ground traffic for which copper is still used.

fiber quickly replaces copper ethernet in telecom in competitive markets (where 1gbps is an actual offer)

> I strongly doubt there are any non-fiber submarine cables.

not for telecom, not anymore, but a number of submarine cable laying ships are equipped specifically for laying high voltage power cables to offshore wind farms. And for things like high voltage cables linking medium sized islands to a nearby mainland (eg: Vancouver Island, BC to the continent).

After submarine telecom, the biggest uses for such vessels are offshore power and the oil/gas industry.

Not just medium-sized islands. The UK has several interconnectors to other European countries for importing and exporting power

https://www.nationalgrid.com/our-businesses/national-grid-ve...

One less than usual at the moment though https://www.bbc.co.uk/news/uk-england-kent-58570893

Some coaxial lines were laid until the 1980s. Seems likely that at least one small island somewhere has a copper submarine cable supplying their data/phone needs still. But it's decidedly obsolete, yes.

Current fiber-containing submarine cables also have electrical lines to power inline amplifiers. Even fiber signals can't travel those kinds of distances without repeaters.

When I lived in the Cayman Islands, the primary submarine cable (I forget its name) was fiber, and I had better net there than I had in the US. It went down for a week or two one time, and the entire island's net traffic was relegated to a much older copper cable that ran to Jamaica. Cayman is a tiny market, but it still crippled our net because the bandwidth was tiny; it was like a couple T1s for the whole population.

Yes operating a non fibre cable is too expensive and does not make sense. Fibre cables on the other hand have remained operational over a long time. AFAIK there are no fibre cables using electro optic repeaters operational anymore. But the earliest fibres which used optical amplification are still operational. This is the beauty about fibre communication. You largely only need to upgrade the endpoints to increase your throughput.

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