New LED breaks law of thermodynamics (sort of)

Akwarius · Mar 10, 2012

[h=1]It just keeps getting better...

MIT physicists have managed to build a light-emitting diode that has an electrical efficiency of more than 100 percent. You may ask, "Wouldn't that mean it breaks the first law of thermodynamics?" The answer, happily, is no.

The LED produces 69 picowatts of light using 30 picowatts of power, giving it an efficiency of 230 percent. That means it operates above "unity efficiency" -- putting it into a category normally occupied by perpetual motion machines.

However, while MIT's diode puts out more than twice as much energy in photons as it's fed in electrons, it doesn't violate the conservation of energy because it appears to draw in heat energy from its surroundings instead. When it gets more than 100 percent electrically-efficient, it begins to cool down, stealing energy from its environment to convert into more photons.

In slightly more detail, the researchers chose an LED with a small band gap, and applied smaller and smaller voltages. Every time the voltage was halved, the electrical power was reduced by a factor of four, but the light power emitted only dropped by a factor of two. The extra energy came instead from lattice vibrations.

Ultra-efficient LED puts out more power than is pumped in[/h]

mcarroll · Mar 10, 2012

Great post!!

I hate to be cliche, but using ambient heat to create (more) light is friggin awesome!

Can LED's have side effects any more opposite when compared to halide/T5 lighting??? :-D

-Matt

P.S. On a related note, this week my halides are scheduled to - fingers crossed - go offline permanently. (Assuming no unforeseen hurdles in building and putting up the GU10 light, of course.)

ReefLEDLights · Mar 10, 2012

mcarroll said:
Great post!!

I hate to be cliche, but using ambient heat to create (more) light is friggin awesome!

Can LED's have side effects any more opposite when compared to halide/T5 lighting??? :-D

-Matt

P.S. On a related note, this week my halides are scheduled to - fingers crossed - go offline permanently. (Assuming no unforeseen hurdles in building and putting up the GU10 light, of course.)

It looks like LEDs are at the beginning. The nice thing is that most LED options are better than all MH options given a 2-4 year cost window.

I went LEDs three years ago on mt 570 mixed and will never go back...26.3 amps v 13.9A now and more PAR. The current Cree XT LEDs are almost twice as bright a lot less in cost than the Luxions I started with...For state of the art components DIY is the best option.

Bill