Hacker News Reader

Comment by dplavery92 | Hacker News Reader

Superconductivity is phenomenologically different than "very low resistance." The excitement about high-temperature superconductors is not only that there will be less power dissipated through power lines, but they will enable new technologies in power generation, high-energy physics research, analog and digital circuitry, sensors, and communications.

View on HN

As someone who knows nothing about this: what would the most obviously useful applications be, if we discovered practical room-temperature superconductors?

Energy storage would be pretty useful, the efficiency could be even better than batteries: https://en.wikipedia.org/wiki/Superconducting_magnetic_energ...

The only discipline in which SMES are an interesting option is high-power pulse sources. For storage of power plant production they are not interesting, as their energy density is order of magnitude lower than those of batteries. They are too heavy and too big. This problem does not go away just by having room temp superconductor. It would have to have incredibly high critical magnetic field strength and be very cheap.

> https://snf.ieeecsc.org/sites/ieeecsc.org/files/CR5_Final3_0...

I think it could scale. If you can directly transfer mechanical stress from the cable to the earth, with no concerns over vacuum or thermal insulation, the economics might work. Even if you can only store ~1 Wh per kg of enclosed rock, it seems possible to enclose millions of kgs of granite in a solenoid.

Maybe fusion power:

https://www.psfc.mit.edu/research/topics/high-field-pathway-...

Definitely fusion, room temp super conductors would allow for better magnets that would better contain the plasma.

It depends on more factors than the critical temperature. Keeping the magnets cool is not so difficult, liquid nitrogen is fairly cheap. You want materials that can sustain large magnetic fields before losing superconductivity.

MRI scanners, tiny and mobile, used like ultrasound whenever, wherever at a tiny fraction of the cost. This would be one 'extension' of something we use already.

But the notion of cheap 'extremely powerful' magnets extends into other things - you'd see 'maglev' type stuff everywhere.

I would imagine some kinds of major computational leaps if it could be done at that small scale.

The efficiency of electric generators changes tremendously without resistance - if built into your local windmill it would improve generation quite a lot.

Yes except the last one. Your windmill is not starved of space to make a big dynamo that uses a lot of copper and is very, very efficient. If the superconducting material is cheap you might be able to do it without using nearly as much material or even without magnets. So it might be cheaper and smaller!

The opposite application (generating torque) is already a home for superconductors. The navy has some superconducting motors in its ships. They're way smaller and have high efficiency over a much wider dynamic range of operating torque. Those are cryo-cooled though.

Fusion power becomes a reality, MRI machines get really small and cheap, your computer gets faster and no longer needs to be cooled, better Maglev trains, lossless transmission of electrical power over long distances.

It's a holy grail technology. You would likely solve all energy problems for the human race forever.

Do you realize all those are wishes, not plausible technology right now? Fusion power has more problems than just magnets needed to be kept cold. MRI machines are a niche thing, sure they could get cheaper but why should average Joe care? Computers don't get just magically faster. Computers need semiconductor switches and those operate based on energy dissipation, you can't just remove that and get a better computer. Maglev trains are overpriced gimmick and lossless transmission would be nice but current estimate of energy losses is like 5%, negligible part of the cost.

> It's a holy grail technology.

In the sense lots of people talk about it as something important, but it is never actually seen or used.

Computers would get magically faster, though. You can build standard digital circuits out of superconducting Josephson junctions, which have much higher switching speeds than semiconductor transistors. A flip-flop was demonstrated to operate at 770 GHz.

"A flip-flop was demonstrated to operate at 770 GHz."

That's data, but not information - flip-flop Hz is far higher than the processor's Hz (which basically has to synchronise over billions of different circuits and run at the lowest common denominator) - so your figure can't be compared to a normal processor's clock speed, only a normal flip flop's speed.

Anyone know what a normal flip flop's speed runs at?

Josephson junction is a very interesting device with many uses, including low energy consumption per FLOPS.

But one big part of the reason the consumption is so low is low temperature. When you try it with room temperatures, switching energy will go up by 2 orders of magnitude (due to higher thermal noise) and this makes the JJ computer efficiency only somewhat better than CMOS. I agree this would still be interesting as refrigeration can be much simpler then and researching JJ-based computers would be easier.

But if we talk about best power/watt, the 4.2K systems or 77K systems are likely to be better than room temp superconducting computers.

> "power generation, high-energy physics research, analog and digital circuitry, sensors, and communications"

Could you provide some reference to these things that are almost there but wait for temp room semiconductors? Sorry, as written this sounds like a vacuous buzzword drop from MIC contractor.

I think you meant "very low resistance" or "very high conductivity", right?

Yes, definitely. I'll edit the parent to reflect.

Reply on news.ycombinator.com