Re: Most Efficient Light Source??
- From: "Fritz Schlunder" <me@xxxxxxxxxxx>
- Date: Fri, 18 Nov 2005 18:53:37 -0700
"manofsan@xxxxxxxxx" <manofsan@xxxxxxxxx> wrote in message
news:1132362520.597844.207810@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> I'd read that incandescent bulbs produce about 13 lumens per watt,
> while halogen lights produce about 90 lumens per watt. LED lamps have
> making inroads with their approx 70 lumens per watt.
Incandescent efficiency is all over the map (as are the other technologies),
but for various types anywhere from 1-20 lumen/watt is not unrealistic. A
conventional 120V 100W regular 750 hour life lamp will probably yeild 17
lumens/watt. Generally speaking the larger the lamp and shorter the life
expectancy the higher the efficiency, the smaller and longer life the worse
efficiency.
Halogen lamps don't produce anywhere near 90 lumens/watt. Typically they
will produce from 20-30 lumens/watt (the 30 lumens/watt ones probably coated
with internal infrared reflecting material), with smaller lamps like those
for flashlights somewhere between 10-20 lumens/watt (or perhaps less for
very small lamps).
LED efficiency is all over the map as well, but even more so. Old ones, or
even modern but low efficiency ones will achieve less than 1 lumen/watt
while good super high effiency modern ones (that aren't necessarily
available yet in large quantities) of white color might achieve the 70
lumens/watt figure or perhaps even more soon.
> But recently some
> Japanese researcher has claimed to produce LEDs with double the normal
> efficiency, at 130 lumens per watt:
>
> http://www.theinquirer.net/?article=27731
This is most likely bogus, although at least a physical possibility. Any
advancements to 130 lumens/watt will most likely be produced by well
established white LED/dice manufacturers such as Cree or Nichia, not some
single "professor" goofing around. Additionally it is unlikely a 130
lumen/watt white LED would be based around a purple LED die since purple
photons have more energy than blue photons, but the phosphors waste any
excess photon energy when downconverting the short wavelength light into
longer wavelengths.
> And now recent experimental results show that nanotubes can emit light
> 1000 times more efficiently than an LED:
>
> http://physicsweb.org/articles/news/9/11/12/1
Obviously bogus or at least their claims are totally bogus. Unless they are
comparing output against say a 1970's vintage LED of very low efficiency,
1000X efficiency is simply not possible. Today's LEDs (including those both
available and those that have simply been demonstrated in a lab, but not
mass produced yet) will achieve overall electrical to optical output
efficiencies from say 1%-50%. 1000X improved efficiency would imply much
greater than 100% overall efficiency, which would imply breaking the laws of
physics. Obviously that isn't possible. TANSTAAFL
Be patient. LED effieciencies are improving (and fairly rapidly at that),
and in due time the ultimate light source will probably be achieved. No
mega "breakthroughs" involving key BS buzz phrases that usually don't mean
much like "quantum," "nanotube," etc. are likely necessary.
.
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