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Ask Slashdot: How Would Room-Temp Superconductors Affect Us?
Bananatree3 writes "While we have sci-fi visions of room temperature superconductors like in the movie Avatar, the question still remains: How would the discovery of a such a material impact our everyday lives? How would the nature of warfare change? How would the global economy react? What are the cultural pros and cons of such a technological shift?" And just as important, in what contexts would you want to see it first employed?
From a human perspective I am rather fond of living at or around room temperature.
Not really: radiative emission is the only type of cooling you can get in space. Depending how much power you're bleeding off elsewhere on your ship, it could be quite difficult to keep things suitably cool. Especially considering that any part of your ship facing the sun is going to be picking up quite a high thermal load.
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You can't predict everything, but you can predict some things. Before the Internet, people could look at networks and think that it would be possible to replace mail order shops and newspapers with a network connection, for example. It's a small leap to go from board games to imagining a machine that could sit in your living room and let you play any board game you wanted on a screen. It's a bigger leap to go from that to the kinds of computer game we have available today.
There are some very obvious applications for room-temperature superconductors, if they could be made cheap enough. The most obvious is long power lines. For example, a moderate sized solar power plant in the middle of the Sahara desert could provide Europe with most of the power that it needs quite easily, but the transmission losses make it unfeasible. With a superconducting power line, it would be just as cheap as local solar power. Taking this a step further, you could have a power ring going all around the world so that there would always be sun shining somewhere and feeding in power. This would cause quite massive changes to the economics of power generation and distribution.
Another obvious place is in transportation. Maglev trains can run very efficiently now, but with room temperature superconductors the cost of building the track would be much lower (you could use electromagnets that would permanently keep their charge and wouldn't require cooling).
Basically, anything that uses magnets or relies on power distribution would suddenly become massively more efficient. More importantly, perhaps, a lot of things that currently use ball bearings and other anti-friction devices could be modified to use electromagnets instead.
It's also worth remembering that superconductors are not just free of electrical resistance, they also have a constant temperature along their lengths. This would make them perfect for anything involving heat redistribution, if they could maintain their superconducting property up to around 350-400 Kelvin. For example, you could easily make a small fanless computer if you could cote the whole of the outside in a layer of superconductor with a pad touching the top of the CPU - the entire case would be a heat sink, and the CPU would never get hotter than the case. House heating systems would be similarly simplified. Rather than having a boiler that heated water and then pumped it through radiators, your radiators could just be coated in a superconducting material with superconducting wires leading into the boiler. As you heated up the end in the boiler, you'd heat up all of the radiators. More efficient and also simpler to build. Not to mention being easier to extend - you could add another radiator by just running a wire from an existing one...
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Most people think of superconductors as merely a "perfectly efficient" conductor. While this is true, it just scratches the surface of what's possible with superconductors. Using superconductors just to improve efficiency wouldn't be that big a deal by itself. It would improve battery life a little bit, and maybe drop bulk electricity transmission overheads, but not by much, and certainly not immediately. Making most superconductors into high-tensile wire is a non-trivial exercise, even if cooling isn't a problem -- and it will be! Just because a material is discovered that can conduct at "room" temperature isn't helpful for wire outdoors in direct sunlight, or in a hot environment inside high-temperature machinery. Last but not least, superconductors have current and magnetic field limits that increase as they are cooled past the transition temperature. A superconductor with a transition temperature of 26C would probably have only a few limited applications above 20C.
The other uses are more interesting, and often more amenable to thermal control:
The Meissner_effect provides magnetic shielding, which is useful for all sorts of things, like amplifiers, or for protecting sensitive electronics. This is also what causes magnets to levitate above Type 2 superconductors. I assume that a room-temperature superconductor would be Type 2, so levitation would likely be possible.
The London moment could be used in gyroscopes and the like.
Josephson junctions provide all sorts of functions, like ultra-sensitive magnetic field sensors (think hard-drives and MRIs).
Still, all of that is a bit... meh. I mean sure, you get less noise in your now ultra-sensitive amplifier, and electricity will cost 10% less than it would have otherwise in 30 years. Is this life changing? Probably not really.
A much more interesting potential application than all of those combined is Rapid Single Flux Quantum digital circuitry. That stuff makes silicon look like vacuum tubes. Think 100GHz+, self-clocking, 1000x as efficient as CMOS, and manufacturable now, with only the cooling requirement the big down-side. If RSFQ could be made to work at room-temperature (or even near it), you could be looking at a sudden massive leap forward in computer power like never before. For example, with a power draw 1000x lower, it would be possible to stack every chip in a typical computer into a little "cube", with much shorter wire lengths, and hence, latencies. We can't do this now, because that cube would literally melt in seconds form the heat.
The reality-check of all this is that many MRI machines are still cooled by liquid helium, even though superconductors that work at liquid nitrogen temperatures have been available for a while. This tells you a lot about the limitations that might restrict the application of even a hypothetical room-temperature superconductor. For example, ultra-sensitive sensors and RSFQ may not work at all, because the tiny signal quanta may be swamped by the background thermal noise. Similarly, manufacturability of wire and maximum magnetic field strength is a key requirement for a lot of applications, like MRIs and electric motors.
Personally, I suspect that the first room-temperature superconductor will be initially manufacturable in bulk only as a thin-film, so expect the first decade or two to be mostly about improved circuitry and sensors more than anything else. This might be closer than people think. For example, there's a harmless quack who claims to have achieved superconductivity at 28C by manufacturing extremely complex copper-based crystals as a thin layer between two different traditional copper-based superconductors. Assuming for a second that he's onto something, it gives you an idea
The idea that the superconductor won't be adding to the thermal load is all well and good, but it doesn't cope with the problem of heat that comes in from solar radiation or heat generated by other parts of the ship like engines. Furthermore, it becomes a self-reinforcing problem, because being unable to dissipate heat makes the superconductor stop superconducting, which only adds to the problem.
Virg
In practice, you can cool satellites pretty darned far. WMAP is cooled to 90K passively. Planck is cooled to 50K passively. So yes, it is very possible to cool satellites to within the superconductivity range of modern high-temperature superconductors.