Suppose such a material were discovered: say it’s as inexpensive and easy to work with as copper or aluminum. This would be a Holy Grail triumph for materials science of course, and obviously extremely useful.
But would it be truly transformative, rather than just incremental? Electric motors are already fairly efficient, and transmission losses in power grids appear to be less than 10% typically.
Are there other applications which where it would make the difference from ‘almost impossible in practice’ to ‘now we can do this fairly easily’?
I think your power grid losses is missing a key part. Long distance transmission power loss is significantly higher so we could have wind & solar farms or Nuke plants where no one lives but get the power to where they do live far more efficiently.
A big factor in high end computers and server farms is still heat. So a room temp superconductor would help computing power and that heat is energy being wasted in most cases.
It should extend the range of electric cars.
etc.
Maglev trains would suddenly become practical, which would cut down transportation costs significantly (or so they say). Might even revive passenger train service in the U.S. though I kinda doubt it.
Room temperature superconductors would allow you to store tremendous amounts of energy in a relatively small package. If affordable, this could solve the electric car battery problem, which has been the holy grail of electric car design for decades. It could also solve the problem with a lot of renewable energy sources, namely that wind and solar don’t produce consistent power.
If you are generating a magnetic field with existing technology, your magnetic field is limited by how much current you can push through your coil of wire before the wire overheats and melts. With superconductors, you could generate scary big magnetic fields, which would mean a huge amount of power out of tiny transformers, and ridiculously powerful tiny motors.
The devil would be in the details. Could the material be drawn into wires, the way copper can? All superconductors stop superconducting at sufficiently high current; how much current can this material take?
I need to do some more research about transmission losses, but on a rather cursory search it seems that long haul losses are not that bad because very high voltages (and sometimes DC lines) are used.
Agreed, eliminating that loss would be a considerable improvement, but would it really be a paradigm shift?
As for server farms: I think most of the heat is generated in the processor and memory chips themselves, which would not be changed by superconductors? Unless of course we have a revolution in how computer components are mad… but that’s another discussion…
Yes, of course, usability is a key point. This may have stopped the copper oxide higher temp materials from finding wider use since they are ceramics, not metallic.
But you’re right: another vital question is how much current can the material sustain. Or to put it another way, how high a magnetic field can it produce or resist before superconductivity collapses. This will determine whether it could be useful for energy storage.
Anyone have a back-of-the-envelope estimate for how much energy density the currently best known superconductors could store if we ignore the cooling issues? Guess I could crank up some rusty university physics, but there are probably folks here with more current skills…
Not a semiconductor guy, but I don’t think generalized conductivity losses are a problem in semiconductor design. As you note, most of the heat generated in computing electronics is doped silicon CMOS semiconductor material driven at high frequency (clock rates). That wouldn’t change unless superconductor switching elements take over for semiconductor gates.
Now, if superconductor material is thermally superconductive as well as electrically, it might change how heat management is designed. Yards-long heat pipes transferring all that computer room heat directly from the package case (e.g., chip heat spreader) to a plant-central cooling point.
That’s a really interesting thought. I wonder if there is any reason to suppose that an electrical superconductor would also be a heat superconductor?
Completely off-topic, Larry Niven made that assumption in the Ringworld SF books… but we digress!
Well, eg a 50-Tesla magnetic field (achievable today!?) would store 109 J/m3.
You can buy superconducting wire today, but now you have to work out the specs of that kind of wire at that strong a field— not sure they are rated that high. But we are talking about a theoretical material…
Well, it’s a reasonable assumption, at least. Ordinary materials with a high conductivity of one sort are usually also good conductors of the other sort, and for mostly the same reasons.
The theoretical thermodynamic limit for flipping, e.g., 1 billion bits per second is only picowatts of heat, so there is clearly room for improvement compared to the current state of the art.
In digital semiconductor devices, supply current is primarily determined by the amount of charge needed to flip a circuit node from a low value (0V) to a high value (power supply voltage). That is determined by the characteristics (gate capacitance) of the physical transistors, but more significantly by the capacitance of the interconnect (wiring) between them. Clock speed determines how often you need to charge and discharge a given node, faster clock = more flips = more current.
In state-of-the-art processes leakage current (current that passes through a transistor when it is in the off state) is also substantial. The power in both cases is primarily dissipated in the silicon in the transistors, not the interconnect.
Superconducting interconnect would decrease propagation delays, allowing for a somewhat faster clock for a given process. What would save a lot of power would be a zero permittivity dielectric between the interconnect wires - zero capacitance so less charge per clock cycle. Not even theoretically possible, since even a vacuum has non-zero permittivity. And even then you might cut power by 25-50%, not a big gain for breaking the laws of physics.
Could it work in reverse? I.e. would using room-temp superconductors for the stator and/or field coil let us generate electricity more efficiently?
The research in Beyond-CMOS is already working to figure out how to abandon copper. As you scale to nm wire dimensions, resistance shoots up, adding heat and delay (RC). Superconducting wires would reduce thermal losses in interconnect to nearly zero and allow use of transmission line interconnect, drastically reducing delays compared to today’s RC delays.
Superconductors are used as heat switches in cryogenic engineering to isolate the cold stage, because the heat conduction gets worse when the material transitions to the superconducting state. Niven was 180 degrees wrong.
It’s easy to understand. Superconductivity is the condensation of charge carriers into a Bose fluid, which can’t, for energetic reasons, interact with random phonons (which carry heat in materials). Because of this, the contribution to heat conduction of these electrical carriers disappears in the superconducting state, leading to lower heat conduction.
Of course, if one came up with a ductile, isotropic, long coherence length, short penetration depth superconductor with a Tc greater than ~500 Kelvin, then:
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All electric aircraft, for which current superconducting designs running at very low temperatures requiring a cryogen or cryocooler can be shown to be lighter and more efficient than conventional designs, would suddenly be low risk.
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Josephson junction based processors, which could run at clock rates of 100’s of GHz with gate switching powers of ~10-19 J and zero “off” losses or wire losses would suddenly become attractive for Beyond CMOS.
IIRC the canonical “superconductor” of heat is superfluid helium II, about 1000x better than copper. That is what they are using today at the Large Hadron Collider. No idea what other matterials might give similar performance.
I used to work in a power plant several decades ago, and the huge steam turbine generators that they had were up around 80 to 90 percent efficiency IIRC. So there’s no huge gain in efficiency for those. It was a coal fired plant, but the only difference between a coal plant, nuke plant, and natural gas plant is what makes the heat. After that it’s all the same steam turbine and generator stuff.
Smaller steam turbine generator sets are only about 40 to 50 percent efficient, so there are some definite gains to be made there. I don’t know how much of that is mechanical though, so I’m not sure how much better magnetic fields would help in that situation.
In any case, the generators could be made significantly smaller, so there is that benefit. The electrical conductors in an existing power plant sized generator’s rotor and stator are HUGE.
Correct. The LHC magnets, despite being Nb-Ti (TC~10 Kelvin) are cooled to ~2 Kelvin by superfluid LHe, because that allows them to be stable. (Google LHC magnet explosion if you want to understand why temperature stability is important).
Magnetic Flywheel Energy Storage.
Ultra-efficient antennas.
That’s worse than a lithium-ion battery, though. Magnets tend to fail structurally at those levels, so even given the superconducting material, building an energy store is going to be challenging.
SMES is a thing though, it’s not the energy density, it’s the refrigeration that has kept the deployment low (though 20-30 MJ units have been demonstrated). It’s advantage over other methods of storing large amounts of power are nearly zero loss during storage and extremely fast charge/discharge time.