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Incandescent lighting is more energy efficient when the filament is placed inside the right "photonics crystal": http://news.mit.edu/2016/nanophotonic-incandes

by ryao 10y ago

Incandescent lighting is more energy efficient when the filament is placed inside the right "photonics crystal": http://news.mit.edu/2016/nanophotonic-incandescent-light-bulbs-0111 http://news.mit.edu/2016/nanophotonic-incandescent-light-bul...

bdamm 10y ago
It's a really cool idea, although their statements about efficiency seem rather questionable to me. LEDs are only twice as efficient as traditional bulbs? A laughable statement, since I get the same light with 1/5th to 1/8th the energy using off the shelf bulbs.
- nkurz 10y ago
  > LEDs are only twice as efficient as traditional bulbs? I didn't see that claim in the article, but I thought these two paragraphs were wonderfully specific: One quantity that characterizes a lighting source is the so-called luminous efficiency, which takes into account the response of the human eye. Whereas the luminous efficiency of conventional incandescent lights is between 2 and 3 percent, that of fluorescents (including CFLs) is between 7 and 15 percent, and that of most commercial LEDs between 5 and 20 percent, the new two-stage incandescents could reach efficiencies as high as 40 percent, the team says. The first proof-of-concept units made by the team do not yet reach that level, achieving about 6.6 percent efficiency. But even that preliminary result matches the efficiency of some of today’s CFLs and LEDs, they point out. And it is already a threefold improvement over the efficiency of today’s incandescents. Which details in that do you question?
  - xyzzyz 10y ago
    Comparing theoretical efficiency of new design for incandescent lighting with commercially available LEDs does not make sense, as theoretical efficiency of white LEDs is also around 40%. I'll consider incandescents once the efficiency of commercially available ones reaches the efficiency of commercially available leds. I bet $100 that it will not happen in next 10 years.
    - nkurz 10y ago
      Comparing theoretical efficiency of new design for incandescent lighting with commercially available LEDs does not make sense Yes. They say they are currently at 6% efficiency, which is better than the worst CFL's and LED's, but far from matching the best. as theoretical efficiency of white LEDs is also around 40% Yes, although one should probably include the power supply. I think the advantage of the incandescent approach is that there are no losses here. I'll consider incandescents once the efficiency of commercially available ones reaches the efficiency of commercially available leds. Sure, sounds wise. Light quality and longevity might be factors too. But what does this have to do with the claim that the article says "LEDs are only twice as efficient as traditional bulbs"? The article can be read as claiming that the worst commercially available LED's are about 2x the efficiency of the best incandescents, and perhaps this is false, but I don't see this as reason to discount the rest of the details. Here's earlier discussion of this approach, which includes a link to the actual paper: https://news.ycombinator.com/item?id=11771001 https://news.ycombinator.com/item?id=11771001
    - ryao 10y ago
      The theoretical efficiency of LEDs is definitely not 40%. LED efficiency has been measured to be 230% with 30 picowatt power consumption: https://www.google.com/amp/phys.org/news/2012-03-efficiency.amp https://www.google.com/amp/phys.org/news/2012-03-efficiency....
      - nkurz 10y ago
        Their claimed efficiency is only sort of true, in that it's measuring the electrical input while ignoring the external heat also used to run the light. By similar logic, one could say that a steam engine running in a very hot room is also over 100% efficient. Also, the "theoretical efficiency of LEDs" is a very different number than the "theoretical efficiency of white LEDs". I think when talking about white LEDs, they are assuming a monochromatic LED pumping a phosphor. But while it's not that practical, in that it's limited to picowatts (10^-12 watts), it is interesting nonetheless. Another similarly surprising example is that the theoretical maximum efficiency of some fuel cells also exceeds 100%, for similar reasons of extracting heat from the environment.

by ryao 10y ago

bdamm 10y ago

It's a really cool idea, although their statements about efficiency seem rather questionable to me. LEDs are only twice as efficient as traditional bulbs? A laughable statement, since I get the same light with 1/5th to 1/8th the energy using off the shelf bulbs.

nkurz 10y ago
> LEDs are only twice as efficient as traditional bulbs? I didn't see that claim in the article, but I thought these two paragraphs were wonderfully specific: One quantity that characterizes a lighting source is the so-called luminous efficiency, which takes into account the response of the human eye. Whereas the luminous efficiency of conventional incandescent lights is between 2 and 3 percent, that of fluorescents (including CFLs) is between 7 and 15 percent, and that of most commercial LEDs between 5 and 20 percent, the new two-stage incandescents could reach efficiencies as high as 40 percent, the team says. The first proof-of-concept units made by the team do not yet reach that level, achieving about 6.6 percent efficiency. But even that preliminary result matches the efficiency of some of today’s CFLs and LEDs, they point out. And it is already a threefold improvement over the efficiency of today’s incandescents. Which details in that do you question?
- xyzzyz 10y ago
  Comparing theoretical efficiency of new design for incandescent lighting with commercially available LEDs does not make sense, as theoretical efficiency of white LEDs is also around 40%. I'll consider incandescents once the efficiency of commercially available ones reaches the efficiency of commercially available leds. I bet $100 that it will not happen in next 10 years.
  - nkurz 10y ago
    Comparing theoretical efficiency of new design for incandescent lighting with commercially available LEDs does not make sense Yes. They say they are currently at 6% efficiency, which is better than the worst CFL's and LED's, but far from matching the best. as theoretical efficiency of white LEDs is also around 40% Yes, although one should probably include the power supply. I think the advantage of the incandescent approach is that there are no losses here. I'll consider incandescents once the efficiency of commercially available ones reaches the efficiency of commercially available leds. Sure, sounds wise. Light quality and longevity might be factors too. But what does this have to do with the claim that the article says "LEDs are only twice as efficient as traditional bulbs"? The article can be read as claiming that the worst commercially available LED's are about 2x the efficiency of the best incandescents, and perhaps this is false, but I don't see this as reason to discount the rest of the details. Here's earlier discussion of this approach, which includes a link to the actual paper: https://news.ycombinator.com/item?id=11771001 https://news.ycombinator.com/item?id=11771001
  - ryao 10y ago
    The theoretical efficiency of LEDs is definitely not 40%. LED efficiency has been measured to be 230% with 30 picowatt power consumption: https://www.google.com/amp/phys.org/news/2012-03-efficiency.amp https://www.google.com/amp/phys.org/news/2012-03-efficiency....
    - nkurz 10y ago
      Their claimed efficiency is only sort of true, in that it's measuring the electrical input while ignoring the external heat also used to run the light. By similar logic, one could say that a steam engine running in a very hot room is also over 100% efficient. Also, the "theoretical efficiency of LEDs" is a very different number than the "theoretical efficiency of white LEDs". I think when talking about white LEDs, they are assuming a monochromatic LED pumping a phosphor. But while it's not that practical, in that it's limited to picowatts (10^-12 watts), it is interesting nonetheless. Another similarly surprising example is that the theoretical maximum efficiency of some fuel cells also exceeds 100%, for similar reasons of extracting heat from the environment.