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Power Idle Science

The Lost History of Sodium Wiring 111

Posted by EditorDavid from the gone-but-not-forgotten dept.
Long-time Slashddot reader Rei writes: On the face of it, sodium seems like about the worst thing you could make a wire out of — it oxidizes rapidly in air, releases hot hydrogen gas in water, melts at 97.8 degrees Centigrade, and has virtually no tensile strength. Yet, in the late 1960s and early 1970s, the Nacon Corporation did just that — producing thousands of kilometers of high-gauge sodium wiring for electrical utilities — and it worked surprisingly well.

While sodium has three times the (volumetric) resistivity of copper and nearly double that of alumium, its incredibly low density gives it a gravimetric resistivity less than a third of copper and half of alumium. Priced similar to alumium per unit resistivity (and much cheaper than copper), limitless, and with almost no environmental impact apart from its production energy consumption, sodium wiring proved to be much more flexible without the fatigue or installation damage risks of alumium. The polyethylene insulation proved to offer sufficient tensile strength on its own to safely pull the wire through conduits, while matching its thermal expansion coefficient. The wiring proved to have tamer responses to both over-current (no insulation burnoff) and over-voltage (high corona inception voltage) scenarios than alumium as well. Meanwhile, "accidental cutting" tests, such as with a backhoe, showed that such events posed no greater danger than cutting copper or alumium cabling. Reliability results in operation were mixed — while few reliability problems were reported with the cables themselves, the low-voltage variety of Nacon cables appeared to have unreliable end connectors, causing some of the cabling to need to be repaired during 13 years of utility-scale testing.

Ultimately, it was economics, not technical factors, that doomed sodium wiring. Lifecycle costs, at 1970s pricing, showed that using sodium wiring was similar to or slightly more expensive for utilities than using alumium. Without an unambiguous and significant economic case to justify taking on the risks of going larger scale, there was a lack of utility interest, and Nacon ceased production.
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The Lost History of Sodium Wiring More

The Lost History of Sodium Wiring

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  • Thirteen years (Score:5, Insightful)

    by PPH ( 736903 ) on Sunday June 09, 2019 @10:49AM (#58735008)

    ... isn't long in utilities time frames. Lets see what happens after a few decades when the insulation gets some pinholes and lets water in. With copper, no big deal. Aluminum oxidizes, turning into a white powder and an open circuit. Sodium ..... yikes!

    • Re: (Score:2)

      by mysidia ( 191772 )

      I suspect for outdoor wiring, they would have stronger weatherproofing in place to keep water from reacting with sodium as the cable jacket ages over its expected lifetime.

      • I suspect for outdoor wiring, they would have stronger weatherproofing in place to keep water from reacting with sodium as the cable jacket ages over its expected lifetime.

        Reading the report, it is kind of doing it's best to present sodium as a good alternative. I'm not so certain. They do acknowledge connector issues, more on the lower voltage lines. But with the specialized training needed to safely install the connections to the outside world, the risks are significant. The problem appears to be water getting into the sodium, starting a slow oxidation, and eventually increasing the resistance, then heating the sodium. The rest can be inferred.

        One thing they didn't go int

      • Re: (Score:2)

        by NFN_NLN ( 633283 )

        It's not a bug, it's a feature.

        Once the jacket degrades sufficiently it fires it's own emergency "flare gun" to get the attention of rescuers/electricians. They should market this and charge extra.

        • Re: (Score:2)

          by mysidia ( 191772 )

          If the whole assembly is something like the Sodium Microtube [techbriefs.com] design,
          then even a "pinhole" in the outer jacket might not be such a problem -- the sodium is still chemically isolated inside the channel sealed by the metal alloy.

          Also the bit about self-repair insulation microchannels contain fire-extinguishing electrically insulative liquid. , and Self-repairing feature. If the wire is accidentally cut, atmospheric pressure pushes sodium deep into the expanding released springy microtube. Simultaneously, p

  • Don't feed it after midnight (Score:1)

    by Anonymous Coward

    And whatever you do, don't get it wet.

  • Well I said it in the title. Worst thing Aluminium oxides can cause a slight case of weakness in the memory, maybe Alzheimer if you are seriously unlucky. Sodium oxidation is a much more "entertaining" process.

    • Re: (Score:2)

      by tomhath ( 637240 )

      According to the Consumer Product Safety Commission, an estimated two million homes in the United States were built or renovated using electrical circuits with aluminum wiring. And, according to the commission and specialists in the field, unless certain safety procedures are undertaken, every outlet, light switch and junction box connected to such circuits is a fire waiting to happen.

      "This is an area we feel very strongly about," said Scott Wolfson, a spokesman for the commission. "Aluminum wiring in a house presents a very serious potential fire hazard..."

      Aluminum wiring causes a lot of house fires.

      • Re: (Score:2)

        by Mashiki ( 184564 )

        Aluminum wiring causes a lot of house fires.

        Aluminum causes a lot of house fires because it's mixed with copper wiring it causes hotspots if you don't use a chemically neutral connector and will start to sulfate in both directions even to other electrical connections, simply making a whole pile of hotspots. And it was used heavily during the peak(70's and 80s) of backstab connectors for electrical outlets. Backstab is just a disaster waiting to happen.

        If you have straight aluminum wiring with no copper anywhere it's perfectly fine, it's the no copp

    • Re:Explosive wiring (Score:5, Insightful)

      by careysub ( 976506 ) on Sunday June 09, 2019 @12:32PM (#58735366)

      Well I said it in the title. Worst thing Aluminium oxides can cause a slight case of weakness in the memory, maybe Alzheimer if you are seriously unlucky. Sodium oxidation is a much more "entertaining" process.

      Less entertaining than you might expect. A small pellet just sizzles (releasing hydrogen) when thrown into water, you need to get a fairly thick chunk (a centimeter or more) to get ignition. It is the least reactive of the alkali metals.

      Sodium wiring sounds crazy on first hearing, but it you think about it a bit, its really isn't. This stuff was not produced for building wiring, but instead for power distribution. The stuff is manufactured with a thick continuous plastic insulation sheathe that water cannot penetrate, unless you cut it. If you cut it you expose just the cross-section of the wire, and if it comes into contact with liquid water immediately, it will might generate a bit of flame until the bulky hydroxide layer smothers it. If it does not common into immediate contact with liquid water it will just rapidly corrode to sodium hydroxide, which will fill the cut end of the cable for some short distance, blocking further oxidation.

      But here's the thing -- that wire is a distribution power line and is carrying megawatts of power at 25,000 volts or so. It you cut, then whether the conductor metal might flame a bit of liquid water is poured on is not going to be an issue since the electrical arc will make an explosion many orders of magnitudes larger. You won't be able to detect any contribution from sodium oxidation in the brilliant arc flash.

      • Question for you, since I lack the knowledge. Oxides almost always (AFAIK) are always bulkier and typically less dense than the parent material. Would the sodium hydroxide bulk enough to swell and possibly split the jacketing?

        My only experience with building materials oxidizing is with steel, particularly in structural applications (girders and rebar) where oxide jacking is a real problem. Rusting rebar is quite capable of destroying the concrete around it. So I wonder if something analogous would happen t

        • Re: (Score:1)

          by Anonymous Coward

          It really depends. Aluminum oxide is protective, and is what protects it from corrosion. Aluminum is nearly as reactive as sodium, HOWEVER, the formation of aluminum oxide insulates the rest of the aluminum from oxidation, and stops the reaction cold.

        • Oxide jacking is fun for the whole family; it's the source of irremovable rusty trailer hitches from trucks (I'm looking at you cherry red sledgehammer TY videos). Im not familiar with the use here but the plastic is very very tough and that includes being essentially malleable not brittle and it stretches. Whatever happens to the conductor, the insulator probably stays on pretty good and anywhere away from damage is fine - source: have burned up and ruined lots of large gauge conventional wiring.
      • Kids would steal the wiring, strip it, and use it for pranks. The "fun" from playing with sodium would cause more damage than stealing copper.

    • Re: (Score:2)

      by ceoyoyo ( 59147 )

      Aluminum is used as a rocket fuel. You have to powder and heat it to get a good fast reaction, but sodium wouldn't be all that different. Both are probably a fire hazard if used as wiring. Aluminum certainly is. That's why we use copper.

    • Re: (Score:2)

      by barakn ( 641218 )

      Aluminum is the most abundant element in the earth's crust. If it were really causative in memory issues or Alzheimer's, we'd all be fucked.

      • I remember reading a paper around 1990 (actually printed on paper, mind you) on increased early Alzheimer in populations where Aluminium kitchenware usage is widespread. I frankly do not advise to make a Google search since results are as diverse as results on GSM's effects on brain cancer. I guess the difference between Al in the crust and Al in its industrial form is that we need to jump thru lots of hops to obtain usable Al bars from natural resources, even from Bauxite.

      • Re: (Score:2)

        by necro81 ( 917438 )

        Aluminum is the most abundant element in the earth's crust.

        To be precise, it's the most abundant metal in the Earth's crust. By weight, the crust is about 46% oxygen and 28% silicon. This makes sense, because just about every igneous rock on the planet is some sort of silicate. Aluminum accounts for only about 8%.

        Sources: [1 [wikipedia.org]] [2 [sandatlas.org]] [3 [space.com]]

  • News for nerds! (Score:5, Insightful)

    by serviscope_minor ( 664417 ) on Sunday June 09, 2019 @11:48AM (#58735250) Journal

    This is a fascinating topic, I'd never have thought it was remotely feasible, nevermind practical enough to actually test.

    • This is a fascinating topic, I'd never have thought it was remotely feasible, nevermind practical enough to actually test.

      It is pretty amazing. IMO, not practical, but interesting experiments. I think they glossed over some of the possible issues. Certainly water is an issue. Those alkali metals just love water. Now imagine a sudden rain shower coming up while you were cutting into a line to install a termination. Or a lightning strike.

      I've worked a fair bit with one of the tamer alkali metals in my past, and the biggest cause of problems is becoming complacent around them. That's when bad stuff happens.

      • The Soviets had nuclear submarines cooled with liquid sodium. What can possibly go wrong??

        • Re: (Score:1)

          by etudiant ( 45264 )

          Not sure about the sodium cooled reactor, but they did have a high temperature reactor cooled with liquid lead.
          Glitch there was that the molten lead started to dissolve the reactor insides.

          Secrecy in the military is really harmful to any kind of progress. We could have much higher reliability high temperature reactors if these experiments had been disclosed and followed up on, instead of getting buried under a layer of secrecy until the Soviet Union collapsed.

        • It does make a good coolant if nothing goes wrong. But liquid Sodium is a real bitch.

          One of the failures the zealots ignore if they even know about it is the Monju Power Plant. Commissioned in August 1995, presumably when reactors were now really safe, it had problems, including a Sodium fire. That fire also happened in December 1995.

          There was a pretty massive cover up, with falsified reports a doctored videotape and gag ordering employees. It's being decommissioned after a cost of around 1 trillion d

  • The "known reserves" of copper have always grown faster than production, "peak copper" is one of the oldest scares since early 20th century, yet even in last 50 years known reserves went from 100 million tons to 16 times that... and it's still growing. The crust of the earth is over 20 miles thick, we've barely scratched the surface. Add to that copper is heavily recycled, over 80% of it is. 35% of copper production is from recycled.

    Not seeing any reason whatsoever to find alternatives to copper other t

    • The problems are usually overstated because there are often known reserves which are bad enough that they only become profitable above a certain price. That said, sparse ores are damaging to mine since you have to remove a lot of crap to get enough metal out.

      Sodium ore is trivial to come by and has essentially no environmental impact. If you have a clean source of energy, you can refine sodium with very little environmental impact.

    • Re: (Score:1)

      by shoor ( 33382 )

      I've seen stuff in the news about utility companies having a problem with copper wire being stolen. I don't know how big a problem it is, but I find it hard to imagine anyone stealing sodium wiring.

      Other people replied about environmental impact of going after the more difficult to reach copper ore, which I thought was a good point. Really, anything that makes less of an environmental imprint, if it's in the same economic ballpark, is worth trying. All these things that impact the environment add up. Th

    • Re: (Score:3)

      by Rei ( 128717 )

      Except that high-power wiring already isn't copper. Long-distance high-power transmission lines are generally steel-reinforced alumium. Copper is just too expensive.

      • we have some copper (well, a type of bronze) high voltage transmission lines ones around here, but I guess they're older. copper still used for medium voltage distribution

        aluminum is even more common, the known reserves of bauxite will go for centuries.

        • Re: (Score:2)

          by Rei ( 128717 )

          As the third most abundant element on Earth, at 8,1% of the crust by mass, it would be pretty hard to run out of alumium ;)

          Like all mined products, ores are mined in order from richest / easiest to extract to the poorest and most difficult. But it would be pretty hard to "run short" on bauxite for alumium production. :)

      • Re:copper one of those flawed "peak" cases (Score:4, Interesting)

        by serviscope_minor ( 664417 ) on Sunday June 09, 2019 @05:14PM (#58736396) Journal

        Except that high-power wiring already isn't copper. Long-distance high-power transmission lines are generally steel-reinforced alumium. Copper is just too expensive.

        True, but it's not just the expense of copper per-se that's the only factor at play here. Aluminium (at DC) has about twice the conductivity per unit weight of copper. If you're stringing wires above ground then reducing the weight substantially reduces the cost of the support structures. Aluminium is also used in some aircraft wiring as well because there the weight saving makes an even larger difference.

    • is squeezing zinc.

  • Kids today don't know squat about sodium. (Score:4, Funny)

    by Chris Mattern ( 191822 ) on Sunday June 09, 2019 @03:24PM (#58736018)

    Why, the shocking lack of sodium taught at schools today is shocking.

  • Apologies in advance for being on-topic -- feel free to mod down...

    So I've been playing with computers and electronics for .... a few years and consider myself a geek. I've never heard of sodium used for electrical wiring. Granted, the trials were around the time I discovered beer and other substances. But hey, like a zombie, I arose out of the fog at least once a year and stumbled around looking for a change of underwear.
  • An underrated and secretly awesome approach is outlined in the not too expensive book by ashby or like this [mit.edu]. You simply take a problem, such as wanting to conduct as much say electrical energy per dollar as possible, so you simply look at the governing equations to see what variables you need and optimal ways to scale your parameters then, using massive amounts of material data, lay out simple to see graphs where it suddenly becomes obvious what material "blobs" or families are in the area you need and wh

  • Anti-theft potential of Sodium metal cables (Score:5, Interesting)

    by Guppy ( 12314 ) on Sunday June 09, 2019 @07:16PM (#58736796)

    You know what would be an absolutely fantastic use-case for Sodium metal cables? Third-world countries where they can't keep metal thieves from destroying the infrastructure.

    You could build power and data transmission lines with this stuff, and it would be almost worthless to a scrap metal dealer. You might still get occasional vandalism by the clueless first-time thief, but the chronic theft problem would be suppressed by the lack of financial return.

    • Re:Anti-theft potential of Sodium metal cables (Score:4, Insightful)

      by Rei ( 128717 ) on Sunday June 09, 2019 @07:36PM (#58736852) Homepage

      Small-gauge sodium wiring would also be interesting for those various military projects to make "self-destructing" electronics for weaponry that can't be salvaged. E.g. a PCB with sodium interconnects kept in an inert atmosphere would oxidize almost instantly if the atmosphere were vented. When intact, it'd also make it much harder to physically tamper with the hardware (e.g. to try to bypass security measures).

  • No cost advantage over aluminum (Score:3)

    by FeelGood314 ( 2516288 ) on Sunday June 09, 2019 @09:49PM (#58737286)
    For the same conductivity it will cost you about the same as aluminum. In high tension wires aluminum has tensile strength so it will obviously win there. In house hold wiring coppers advantage is that any idiot can actually connect the wires. I think everywhere that ever experimented with allowing aluminium wiring learned that there are enough idiots around that it just can't be allowed. That leaves industrial where you have trained technicians. Sodium wire bends more easily but that doesn't make up for it's problems with water and air. Aluminum oxide is an insulator and will stay on the aluminum. Sodium hydroxide is very water soluble. It won't protect your cable at all. So the connections are going to be even more difficult to make than aluminum. You also have that low melting temperature.

    It was worth researching though. If enough companies actually used it maybe the cost of sodium would have dropped low enough to make up for it's short comings.
  • next we make wiring out of mercury. gotta have more fun somehow.
  • If sodium is a better conductor by weight, would it make sense to use it for space applications where oxidation isn't an issue and every gram counts? Or would the complications during manufacturing balance this out?

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