9 ms·

None of the things you listed are limited by the conductors in them. The efficiency of high voltage AC power lines is limited by capacitive coupling to ground.

• vagab0nd 3y ago
  > Battery charging is limited by the cell chemistry. Yes, but superconductors don't have that limitation, do they? You just dump current into them.
  • jrockway 3y ago
    Are you thinking of supercapacitors?
    • civilitty 3y ago
      He's thinking of superconducting magnetic energy storage: https://en.wikipedia.org/wiki/Superconducting_magnetic_energy_storage https://en.wikipedia.org/wiki/Superconducting_magnetic_energ... Currently they're only feasible as high quality power sources for fabs and other industrial uses because of the operating costs of cooling the superconductors.
      • jacquesm 3y ago
        Also used for grid stabilization.
        • entropicdrifter 3y ago
          So superconductor supercapacitors
          • heisenzombie 3y ago
            More like superinductors than supercapacitors - the energy is stored in a magnetic field (inductor) and not an electric field (capacitor)
    • dfox 3y ago
      There is a theory that with room temperature superconductors you could use an inductor for practical energy storage.
      • bananapub 3y ago
        what are the practicalities of storing enormous magnetic fields and then collapsing them to draw power? that seems...not obviously a good idea.
        • dfox 3y ago
          Well, exactly. While there is a way of getting some of the stored energy as an controlled power, most of the failure modes of such a thing leads to uncontrolled release of the stored energy, manifested by the whole thing just somewhat instantaneously turning into very hot gas.
          • nrdgrrrl 3y ago
            [dead]
      • deleted 3y ago
        [deleted]
  • mminer237 3y ago
    They have low losses when storing power, but power has to be stored in the magnetic field. They have a limit on acceptable magnetic field strength called the critical field though, above which it stops being a superconductor and bad things™ happen. Current SMES systems have an energy density of about ¹⁄₅₀th of current Li-ion batteries.
    • vagab0nd 3y ago
      You are right about the energy density and limitations. I was more focused on the fast rate of storage and retrieval.
      • therein 3y ago
        We already have incredible supercapacitors. https://www.eaton.com/gb/en-gb/catalog/electronic-components/xl60-supercapacitor.html https://www.eaton.com/gb/en-gb/catalog/electronic-components... I have 4 at home and blows people's minds when you melt a wire with it. Incredible rapid current delivery.
        • XorNot 3y ago
          They don't store any meaningful amount of electricity (which is why they haven't supplanted Li-Ion batteries for power tools) and more importantly they have a cycle-life - they degrade from usage (source: my wife works for a supercapacitor manufacturer). You also get losses from practical usage - i.e. no one can build a 3V supercapacitor that has decent endurance (you can totally build one which will work, but you're rating it knowing that every cycle is damaging it).
          • skykooler 3y ago
            Why do cycles damage supercapacitors? My understanding is that in batteries this is caused by ions not returning to their original spot in the electrodes, but I thought only the electrons moved in capacitors?
  • inportb 3y ago
    Overlooking the cell chemistry issue... ... you cannot just dump unlimited current through a superconductor. Once you exceed the critical current density, your superconductor becomes a regular conductor.
    • mytailorisrich 3y ago
      And in any case whatever power source you're using cannot deliver infinite power.
      • tmpX7dMeXU 3y ago
        Who said infinite power?
        • qsdf38100 3y ago
          It's implied by instant charging. The power would be the battery capacity divided by 0.
          • deleted 3y ago
            [deleted]
          • sharlos201068 3y ago
            No one means literally zero time to charge. A couple seconds compared to minutes or hours is virtually instant for practical purposes.
            • qsdf38100 3y ago
              Let me keep being pedantic and notice that a typical phone capacity of 10000 Joules divided by 2 seconds is still 5 kW of power, so not a trivial amount. I'd think 30 seconds (333 Watts) is more realistic.
              • Denote6737 3y ago
• nextaccountic 3y ago
  > CPU heat output is limited by the resistance of the semiconductors. Can't superconductor help here?
  • Sharlin 3y ago
    Superconducting semiconductors? I doubt such a thing is possible.
    • weard_beard 3y ago
      Doubt no more. Its called a Josephson junction. https://en.wikipedia.org/wiki/Josephson_effect https://en.wikipedia.org/wiki/Josephson_effect
  • anonymous_sorry 3y ago
    It's not obvious to me how it could. Transistors require a semiconductor.
    • disintegore 3y ago
      To my knowledge, computers can be designed without any transistors
      • entropicdrifter 3y ago
        They can, but then you're talking about a totally different physical scale of computer. Transistors are useful because we know how to shrink them to a scale of nanometers, in particular we know exactly how to do that with transistors printed with lasers onto silicon chips. We'd have to reboot the CPU manufacturing industry with new base materials/technologies. It's hyper-specialized tech, so it'd probably take over a decade from now to be seen in useful, everyday technologies.
  • Taniwha 3y ago
    Only a little, one big limitation in chips is RC wire delays (the distributed capacitance along a wire needs to be charged/discharged for a signal change to pass) - due to edge effects capacitance doesn't scale with the area of the wire - but R does (inversely so wires have gotten slower) - so as chips have got denser wires have not got faster at the same rate, when I first started building chips we mostly only cared about gate capacitances - now RC delays are a big deal - if R went to 0 RC delays would too - things would get faster
• mNovak 3y ago
  In the RF world (particularly at mm-wave frequencies), even copper has very non-negligible losses. In most passive circuits conductor loss is the limiting factor of performance. No idea if this material retains the same properties at such frequencies, and is compatible with typical lithography or other fabrication techniques, but it'd be amazing if so.
  • namibj 3y ago
    Particle accelerators sometimes use superconducting niobium resonators at e.g. 1.8K offering a Q of 5e10 at 1.3 GHz. But apparently their surface resistance scales with the square of frequency, unlike the square root in normal copper. So maybe just just t normal conductors like copper, silver, graphene (assuming the latter can be commercially made to surpass silver in RF surface resistance).
    • jacquesm 3y ago
      Silver is very good for RF power work, so good that I doubt that anything will be able to supplant it on a cost basis because you only need a tiny little bit of it to plate your copper carrier to get really good results. Obviously not perfect, there is still some resistance but it's hard to compete with because of the combination of properties in terms of ductility, flexibility, resistance to deep corrosion and so on.
• XorNot 3y ago
  Superconducting powerlines would be able to transport DC electricity with 0% losses. To put this in context: you could put solar panels in California, and send every watt of power to Alaska or New York, while losing nothing in the transport.
  • contravariant 3y ago
    Yeah at those kinds of scales I get doubtful. At those scales the electrical fields themselves begin to exert inertia on things, to the point that you could cut most power lines and they wouldn't stop catastrophically, they'd continue catastrophically (a problem that only gets worse with superconductors, as happened to CERN when they accidentally vaporised a length of superconductor that had become conductive). It could definitely open up the road to long distance high capacity power lines, but somewhere along the line reality is going to make things difficult. It's not magic after all, just sufficiently advanced technology.
    • soligern 3y ago
      You could bury them or have very high overhead lines. Being able to have near instantaneous, lossless energy transfer would make it worth it (minus whatever impediment the GOP tries to put in the way to bolster gas/oil, but that’s just political).
    • burnished 3y ago
      Could you spot me a link to that CERN incident or on the topic of superconductors becoming conductive (looooool)? All I got for CERN was reports about gas leaks but I find myself very curious about the way superconductors fail now
      • contravariant 3y ago
        Here is their own article on the incident: https://home.cern/news/press-release/cern/cern-releases-analysis-lhc-incident https://home.cern/news/press-release/cern/cern-releases-anal... Doesn't sound too spectacular but it took them over a year to fix all the damage.
• nwiswell 3y ago
  > CPU heat output is limited by the resistance of the semiconductors. This is not true anymore. At leading edge process nodes (i.e., smaller conductor pitch), the bulk resistivity of copper changes dramatically because it is increasingly dominated by ballistic electron scattering on the interfaces and grain boundaries: surface area has decreased as a fraction of volume and the average grain size has shrunk to fit inside the interconnect lines. Alternative metals like Cobalt and Ruthenium have been proposed and to some extent used in production as an alternative to Cu for the low interconnect layers, but they just arrest the trend -- the fact is that the interconnect resistance is much higher than it used to be. It's also why a lot of the big players like TSMC and Intel are investing heavily in backside power delivery. Here is an accessible article on the topic: https://www.fabricatedknowledge.com/p/backside-power-delivery-and-bold https://www.fabricatedknowledge.com/p/backside-power-deliver... (Also: high-voltage DC power is commonly used for long-range transmission and does not have coupling issues)
  • Taniwha 3y ago
    Yes RC wire delays have becoming more important than gate capacitance for a couple of decades now - if R goes to 0 RC delays do too
    • whatshisface 3y ago
      I guess the next limiting factor would be LC delays.
  • throwawaylinux 3y ago
    No it pretty much is true, well it's the power draw from switching transistors and from leakage losses. Resistance in the metal wires is not so much a problem for power as it is for signal propagation delay. That is the biggest problem with R skyrocketing in M0/1. And backside power delivery is to relieve congestion in the interconnects. That's typically one of the limiting factors in complex logic designs now, transistor densities of under 70% aren't uncommon. That's what "Removing the power signal and signal line to just a signal line would free up space for more transistors." line is about in the link. Power delivery losses aren't nothing, but they aren't a big fraction of energy in today's CPUs. Eliminating most wire delay would be a huge benefit though, and could be a pretty big revolution. Not just within the core or on the die. You're still going to have to switch those transistors and burn current on leakage though, so no cold CPUs just yet.
• tomxor 3y ago
  > CPU heat output is limited by the resistance of the semiconductors. Technically true but not applicable... Super conducting CPUs already exist (at below room temp), and they don't use semiconductors. They don't have an exact transistor equivalent but use digital logic circuits such as Quantum Flux Parametron (QFP) and rapid single flux quantum (RSFQ), which are comprised of Josephson Junctions [0] which are made from the same super conducting material. Relying on quantum effects of a gap between two conductors rather than specific material properties. So while it is true that CMOS are limited by the resistance of both the conductor interconnects AND the semiconductors. Super conducting circuits only appear to need a conductor... There are other drawbacks, such as larger feature sizes due to the nature of super conducting materials, and QFP and RSFQ might be more complex? but this is potentially offset by huge advantages: zero resistance buys not only power efficiency and minimum heat generation (as required by landauer limit), but also allows circuits to be driven at a higher clock, so far demonstrated to 770GHz for one CPU [1] [0] https://en.wikipedia.org/wiki/Josephson_effect https://en.wikipedia.org/wiki/Josephson_effect [1] https://spectrum.ieee.org/superconductor-logic-goes-lowpower https://spectrum.ieee.org/superconductor-logic-goes-lowpower
  • throwawaylinux 3y ago
    > so far demonstrated to 770GHz for one CPU That's not a CPU, it's a simple circuit. From the article, "Simple superconducting logic circuits have been shown to operate at speeds of up to 770 gigahertz." Exotic semiconductor transistors can switch that fast, record being over 800GHz I think. Regular transistors of the type in your phone can probably do around 200-300GHz. Not to say there could not be revolutionary designs opened up with superconducting wires or switches, just the switching speed itself doesn't necessarily tell us one way or the other.
    • SomeoneFromCA 3y ago
      I doubt that regular cellphone transistor can _switch_ at 200Ghz; their GBW might be in that range, but for reliable switching you need clock frequency at most 1/10 of GBW
• cogman10 3y ago
  > The efficiency of high voltage AC power lines is limited by capacitive coupling to ground. And to this point, HVDC has been slowly rising as a viable alternative beyond just undersea transmission. A mistaken belief is that AC is more efficient than DC. What AC is is more easy to transform from one voltage to another (until somewhat recently). That makes it easier to run AC at 1 MV and then step it down to 240V for residential applications. The cost is as AC voltage goes up, capacitive resistance increases. This is part of the reason why high voltage lines have such huge towers with the lines far apart. An HVDC line, however, can be put underground (or water) without suffering power losses. It's voltage can go well above that of AC voltages with the only limit being how much insulation we need for the line. Super conductors are nice, but only in the "now we can run 1 billion amps at 100V" sense to avoid the capactive resistance. Without any sort of special materials you get most of the benefits of super conductors by using HVDC. The only real downside is high voltage DC is still super dangerous. Cut the insulation and you've got something that can arc meters whereas a superconductor at lower voltages would be about the same danger as any other conductor at lower voltages.
  • heisenzombie 3y ago
    Minor nitpick — "now we can run 1 billion amps at 100V" — there is a limit to how much current you can put down a superconductor. For example I think commercial YBCO superconductor tape will do roughly 1000A/mm^2 (and even that requires being significantly below its critical temperature). That’s a pretty high current density compared to what’s feasible with copper — don’t get me wrong — but a billion amps would still require a pretty huge cable even with a superconductor.
    • tomxor 3y ago
      Presumably everything in the chain, every junction, would also need to be a pure super conductor? Anything else would be susceptible to instantly melting or vaporising. So unless someone comes up with super conducting welding I guess that would mean no junctions.
    • SomeoneFromCA 3y ago
      Not only that, the magnetic field around the wire at 1 bln amps will be way too large. It will like pick up nails from the ground easily.
• jojobas 3y ago
  >The efficiency of high voltage AC power lines is limited by capacitive coupling to ground. As often in engineering, the sweet spot is where multiple factors have ~equal contributions, so even a 50% win in one of the factors can't give you that much benefit. For high voltage AC power lines it's Ohmic losses, corona discharge losses, and inductive losses.
• sheepscreek 3y ago
  But it is. A significant part of electronics engineering is dedicated to heat dissipation. So what do we stand to gain? At least a slight improvement in efficiency of transmission. And a huge improvement due to simpler heat dissipation needs. So this might mean way faster battery charging - like 500 miles worth of charge in 5 mins. We’re mainly limited by how hot the batteries get during charging.
  • Beldin 3y ago
    We're about halfway there already, just by cooling: 250km in under 4 min (1). (1) https://www.tue.nl/en/news-and-events/news-overview/13-07-2023-inmotion-develops-fastest-charging-electric-race-car-in-the-world https://www.tue.nl/en/news-and-events/news-overview/13-07-20...
    • chrismorgan 3y ago
      I love that electric vehicle charging can be expressed in speeds (that is, distance divided by time). 250km/4min is 3750km/h, a touch over Mach π.
      • internetter 3y ago
        I like this. Woah, your car charges at 4000 kilometers a hour? Mine only does 3000!
    • sheepscreek 3y ago
      This is incredibly exciting. The biggest hurdle as yet to mass adoption.
• soligern 3y ago
  We’re not talking about charging existing batteries but superconductors where you just “trap” large amounts of electricity in the superconductor for future use.
  • ben_w 3y ago
    Unfortunately magnets put forces on themselves, which means you’re limited to storing up to about as much energy as it would take to break the thing making the field; or, to put it another way, it’s about the same range of energy densities as springs or rubber bands. Earlier discussion: https://news.ycombinator.com/item?id=36954783 https://news.ycombinator.com/item?id=36954783
    • eternityforest 3y ago
      Does that mean you would get equal(but probably insanely more dangerous) performance with a giant miles long spring instead of the proposed superconducting loops?
  • raducu 3y ago
    Do you mean superconductors create super capacitors, or how do you want to trap the charge? Or store in coils, as "magnetic energy"(forgot the name for it)
• jader201 3y ago
  > - Lossless transport of energy - Batteries that don't take any time to recharge - Faster CPUs. Much faster with no heat to burn your lap. Finally someone is speaking English in these room-temperature superconductor threads that I can actually understand and get excited about! > None of the things you listed are limited by the conductors in them. Never mind. :(