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LED's Efficiency Exceeds 100%
New submitter Paul Fernhout writes "Physicists from MIT claim to have demonstrated that an LED can emit more optical power than the electrical power it consumes. Researchers suggest this LED acts like a heat pump somehow (abstract). Is it true that 230% efficient LEDs seem to violate first law of thermodynamics?"
I once observed a low threshold LED (has a much less than 1.4V on-voltage) that was only attached by one lead, with the other lead hanging freely in space. The LED was quite clearly "on". When you put your finger closer to the free hanging lead (but not touch) it got brighter. It was just acting as an antenna in a room with lots of EM radiation around, and the induced current was enough to light it up.
"I have never let my schooling interfere with my education." - Mark Twain
No, and they are using an LED in the far IF spectrum at elevated temperatures. Actually the effect is difficult to distinguish from thermal radiation - a darkening of the LED might also explain it (?). Still, I think the paper is genuine, and under very specific circumstances a combination of thermal and electric energy can power an LED.
The bigger question is: can this be achieved in any real scenario, and not just in minimal amount? That is going to be much tougher.
It's a neat bit of physics, and will probably have implications for device efficiency and other applications.
It's the solution for global warming.
Take a large bank of these over-efficient LEDs. Shine them on a solar panel. Power the LEDs from the solar panel output. Everything in the vicinity of the LEDs gets cold. Make lots of these. Problem solved.
If it seems like a perpetual motion system, it probably is. If you've got a 230% efficient LED, then you can have a 50% efficient solar panel and still come out ahead.
The only problem is what to do with all the excess electricity these things will produce.
I think this could be applied as an interesting method to cool an object by applying a voltage to it... if it consumes both the energy of the voltage and the ambient temperature of the device.
Sounds like the LED is effectively re-directing the thermal radiation then, which is kind of cool. (No pun intended.) Could you daisy-chain this so the light output of one super-powers the next to draw heat away from a source? You'd be siphoning off as much heat energy from the system as the electric energy you're putting in in that case.