In a study recently published by “Physical Review Letters,” a pair of MIT researchers demonstrated that an LED can actually put out more optical power than the electrical power fed into it. Although this might on its face seem to violate the law of thermodynamics, in reality there is a phenomenon taking place which allows the LED to actually use the heat energy created by the LED to add to its photon production. The energy fed into their LED was so small, and the output so meager, they were able to take advantage of a LED’s tendency to become more efficient the lower the current fed into it. Although their demonstration doesn’t say anything important about potentially increasing the efficiency of LEDs used for general illumination, it does demonstrate the extreme efficiency potential with which LEDs operate.
In the real world, commercial grade LED lighting isn’t quite so efficient. In terms of general energy conversion to visible light output, today’s LEDs are capable of reaching up to 80 percent efficiency under perfect conditions, but for the most part average around 60-70 percent. Still, this is a significant improvement over incandescent bulbs which waste up to 90 percent of their energy as heat. LEDs even surpass metal halide for actual energy to light conversion, with metal halide converting about 50 percent of the electrical energy supplied into visible light.