A photon-recycling incandescent lighting device

https://www.science.org/doi/10.1126/sciadv.adf3737

by adrian_b • 3 years ago

126 90 3 years ago

That's remarkable. I was afraid this was going to be a pure theory/simulation paper, but they built an incandescent light source that selectively recycles infrared photons back to the hot emitter, thereby dramatically improving the luminous efficacy. It's a white light source that produces a continuous spectrum in the visible range, like other incandescent light bulbs, but has efficiency comparable to LED lighting.

adrian_b11• 3 years ago

TLDR:

This paper demonstrates quite convincingly (because the descriptions are very detailed) that the ancient Edison light bulb (i.e. with light emitted by incandescent carbon) can be revived by using modern technologies in a form that can be better than the current LED lamps.

The first incandescent lamps had 2 disadvantages, short lifetime and low efficiency.

The evaporation and oxidation of the incandescent carbon can be avoided by a structure made of carbon nanotubes that works in argon. The claimed lifetime (based on accelerated aging tests) is as good as for LEDs.

The low efficiency is solved by using a lossless optical filter (i.e. one that transmits the visible light and reflects back the infrared light) to prevent the heat loss from the lamp by radiation other than the useful light output.

This method can reach the maximum energy efficiency determined by the human vision characteristics, unlike the current LED lamps, which are unavoidably limited to a value lower than that by the losses caused by the fluorescent light conversion.

The design of the lossless optical filter is a difficult optimization problem due to the large number of parameters. Their solution, which is completely described in the paper, is claimed to have been found by a machine-learning algorithm.

maicro• 3 years ago

I'm not going to read the paper to check your work, but excellent TLDR - thanks X)

muser8• 3 years ago

Fantastic summary!

I wonder if the economics will make enough sense to overcome entrenched interests and the legislation backing them.

It be great to have efficient incandescent light and put the failed promises of LED longevity behind us.

tasty_freeze• 3 years ago

As far as I know, there isn't a law banning incandescent lamps. The law stated that such lighting needs to achieve a certain level of efficiency or greater, which in effect banned existing 1% efficient incandescent lights.

It be great to have efficient incandescent light and put the failed promises of LED longevity behind us.

In my experience, the main failure mode of LED bulbs is the power supply -- they engineer every penny out of them even at the cost of reliability. Second, nearly all bulbs are dimmable, which complicates the power supply, because customers faced with dimmable vs non-dimmable will pick the dimmable one.

Another factor is if you read those claims about 20 year lifetimes and such, often there is a footnote saying something like "assuming it is on for 3 hours a day or less".

Finally, you are assuming that this new technology won't suffer the same fate as the LED bulbs. If they take off, they will be cost reduced at the expense of longevity. I saw the same thing happen in the era of floppy disks -- over time the price was reduced by a factor of 20 but reliability went down in parallel.

orbital-decay• 3 years ago

the failed promises of LED longevity

LEDs last remarkably long if used correctly. You can make a light that will easily last thousands/dozens of thousands of hours. What doesn't last is a typical LED lightbulb for legacy sockets, because of the planned obsolescence/race to the bottom, and because it's a complete device (power supply, heatsink etc) which is far too powerful for its form-factor. Not sure what of that you expect to change.

neilfrndes• 3 years ago

Check out Dubai Lamps: https://hackaday.com/2021/01/17/leds-from-dubai-the-royal-li...

Dubai Lamps are special LED lamps designed by Philips for high efficiency and very long operational life. A simple design change reduces stress and excess heat that otherwise significantly lowers the mean time before failure of regular LED lamps

UncleOxidant• 3 years ago

I don't see any discussion of manufacturing costs, anything here that might be more expensive than current LED lighting?

adrian_b11• 3 years ago

With a bulb made of alumina and having a window made of quartz on which thin films have been deposited, it would be more expensive than a traditional incandescent lamp, but that would be compensated by the high efficiency and long life.

If in mass production, I see nothing that would prevent it from being cheaper than a comparable LED lamp.

I am not familiar with the technology used to make the incandescent band made of carbon nanotubes and boron nitride ceramic, but everything else is made with standard equipment that is widely available.

scythe2• 3 years ago

The key innovation here is the IR-selective-reflection bulb coating. As such:

Fabrication of the VTIRF window
The quartz substrate with a size of 25 mm by 50 mm is cleaned by bath ultrasonication using acetone, ethanol, and deionizing water for 10 min. The Al2O3 and HfO2 layers are deposited by atomic layer deposition (R200, PICOSUN) at 255°C using trimethylaluminum (Strem Chemicals) and tetrakis(dimethylamido)hafnium(IV) (Strem Chemicals) as precursors, respectively. The oxidizing agent is H2O. The precursor carrier gas is N2 (99.999% purity, Shanghai Weichuang Gas). The Ag-Ge alloy and SiO2 layers are deposited by electron beam evaporation (PVD 75, Kurt J. Lesker) in vacuum.

I'm no expert on how LEDs are made, but this coating certainly doesn't assemble itself.

zubiaur• 3 years ago

This seems similar to HIR technology, widely available on car headlamps:

“The HIR1 (9011) and HIR2 (9012) Halogen Infrared Reflective bulbs have micro-thin layers of electro-deposited coating on a specially-designed bulb. The coating reflects the filament's infrared (heat) back onto the filament, which results in a hotter filament that produces more light without increased power consumption, shorter bulb life, or extra heat production.“

adrian_b11• 3 years ago

The principle is the same, but here a much more sophisticated implementation is shown, which is able to achieve better performances than the LED lamps.

narrator• 3 years ago

Carbon nanotubes are about as toxic as asbestos. So unless you're making that bulb for somewhere that's absurdly hard to change, it's probably a bad idea.

Accujack• 3 years ago

Asbestos isn't toxic at all unless the fibers are airborne.

Unless you disturb the nano tubes in the device in such a way that they become airborne, they're safe. Probably they're less dangerous than the mercury in the CFL tubes.

aappleby• 3 years ago

Carbon nanotubes are flammable.

Etrnl_President• 3 years ago

Replace Tungsten with Osmium for longer lifespan, and operate at lower voltage.

milleramp2• 3 years ago

The optical filter is critical to the design, and big curiosity to me. Normal dielectric filters have a large angle dependence. Of course and It’s solved by machine-learning, I am hopeful but skeptical. Need to dig further into this.

nine_k3• 3 years ago

I don't think a "filament" would work.

To obtain the efficiency gains, the device needs to reflect most of the IR photons back onto the hot emitter, which would be a filament in a regular incandescent lamp. But the filament's cross section is small compared to lamp's. If an IR photon must reflect 1000 times before hitting the filament (very optimistic!), and the reflector reflects 99.9% of the IR photons back inside, only about 37% of the IR photons will hit the filament. And at that they only have about 5-10% chance to be re-emitted as visible light, depending on the temperature.

So, for the economy of the photons to work, a large black glowing ball would be needed; any photons inside it would be recycled, and it would readily absorb most of the photons returned to its outer surface by the miraculous IR reflector.

Thermal losses would still be pretty noticeable because argon can't have too low pressure, else it won't prevent the evaporation of the emitter. The device would run pretty hot, which is a source of inefficiency.

I don't know whether it would be more efficient than the large and very hot arc lamps [1] which illuminate stadiums or even large shopping centers, with electrical efficiency above 50%.

[1] https://en.m.wikipedia.org/wiki/High-intensity_discharge_lam...

Etheryte2• 3 years ago

They built one and it recycles 92% of the IR radiation, what do you mean?

adrian_b11• 3 years ago

You are right, but the authors are not fools, so they do not use a filament.

The incandescent part has the form of a rectangular tape, with the front side made of black carbon (nanotubes deposited by CVD) and the back side made of white boron nitride, so that most of the radiation is directed towards the front, i.e. towards the exit window, to minimize the heating of the enclosure (which is made of white alumina, to minimize the absorption of the radiation that does not go out through the window).

If the alumina enclosure gets hot, the efficiency can be further increased by reducing the heat loss with an extra surrounding layer of thermal insulator (which could be provided by a plastic or ceramic socket).

Increasing the efficiency up to the ultimate limit imposed by the human vision may become too expensive to be worthwhile, but there is no other obstacle except cost, unlike for the current LED lamps with fluorescent phosphors.

I have never heard of any arc lamp that has any chance of even remotely approaching a 50% efficiency, when counting only the useful light.

Otherwise, even an archaic incandescent lamp can approach an 100% electrical-to-light efficiency, but almost all of the light output is in the form of useless infrared light.

Besides using an incandescent emitter with a lossless optical filter, the only other way to approach the ultimate efficiency for lighting (with a good color rendering) would be with a lamp including at least 4 LEDs or laser diodes of different colors.

The latter solution is much more expensive, requires electronics for compensating the change in time of the color temperature and it is currently limited by the lack of semiconductor emitters with high efficiency for yellow and green light.

Gordonjcp3• 3 years ago

Is the efficiency of an incandescent lamp really a problem though? If your power comes from renewable sources then over its entire lifespan an incandescent bulb has to be way cleaner than an LED.

In general something that's a coil of wire in a glass bottle with the air sucked out that you could reasonably make in a blacksmith's forge is going to be less environmentally horrible than a hundred grams of plastic, fibreglass, epoxy, copper, tin, bismuth, gallium arsenide, phosphorus and so on that has to be put together in a multi-billion-dollar factory.

adrian_b11• 3 years ago

The difference in efficiency is too high to not matter.

In the past, I had used for the lighting of my house various combinations of 100-W incandescent lamps.

When better technologies have appeared, I have substituted them with other lamps having an 1500-lumen light output, which is slightly more than provided by the 100-W incandescent lamps.

With compact fluorescent lamps, I have used 22-W lamps, while during the last decade I have been using 13-W LED lamps (with 1500 lumen at a pleasant 4000 K color temperature, i.e. only slightly warm, not noticeably yellow, like the lamps with a color temperature of 3000 K or less).

Even the early prototype described in the research paper can achieve 1500 lumen at 8.7 W.

The difference between 100 W and 8.7 W is too large to ignore. In my case, both transitions, to CFL, then to LED, have been extremely visible in my monthly bills.

mike_hock3• 3 years ago

useful light output

Part of what makes LEDs and neon lights feel so fake and sterile is that they give off visible light but no perceptible heat.

You can feel the heat from a 100W light bulb on your skin and you pick up on that subconsciously.

That being said, getting an even spectrum back would be a nice "improvement" (regression fix).

db48x3• 3 years ago

Personally I’ve always disliked feeling the heat of an incandescent lamp. And I’m fairly certain that one of the advantages of electric lighting over gas was the _reduction_ in heat produced while lighting the room.

MengerSponge• 3 years ago

I bet you've just learned to associate the continuous spectrum from incandescent bulbs with the heat they also emit. Have you ever been in a space illuminated by sun tubes or skylights? Did that light feel fake and/or sterile?

itronitron• 3 years ago

It's like a wood stove, but for light.

dexzod• 3 years ago

The short lifetime of incandescent bulbs was by design https://spectrum.ieee.org/the-great-lightbulb-conspiracy. Otherwise they can last pretty long. This one is on since 1901 https://en.wikipedia.org/wiki/Centennial_Light

philipkglass2• 3 years ago

Running the filaments hotter makes the bulb more efficient but also shortens the lifespan due to faster filament evaporation. You could get very long life by under-powering the bulb but then the low efficiency of incandescent lighting would go lower. That's the other remarkable thing about this paper. They use a ceramic instead of tungsten as the hot emitter, and calculate that it should have a very long lifetime.

hashmash• 3 years ago

The Centennial Light produces very little light and isn't very practical. https://www.urbo.com/content/the-lightbulb-conspiracy-shinin...

Syonyk• 3 years ago

It's really more "by physics." You can pick how you want to run a tungsten filament and end up with either a long life bulb, or a high(er) efficiency bulb, but not both. The ~1000 hour goal was, at the time, an attempt to optimize the total cost of lighting - bulb and power combined. As your bulb lasts longer, you get rather fewer lumens per watt.

A typical 1000 hour rated 60W incandescent (an old one, not the new halogen "efficient" ones - 28% less power for 28% less light) will put out around 850 lumens. I have a 20k hour rated bulb with the same output - but it pulls 75W. Over the lifetime of the bulb, that increased power use is quite a bit more expensive than replacing bulbs would be - but they're designed for places that are harder to access, or that are high vibration (typically, long life incandescents also have more supports, so they work better in higher vibration environments).

There's no magical tungsten filament, 60W, 850 lumen bulb that will last 10k+ hours. It's simply not possible within the normal constraints.

This new tech, though... I'm very excited by it!

npunt• 3 years ago

This uses carbon nanotubes, which can have asbestos-like effects on the lungs. Nanotubes are great for tons of applications, but especially those where safe disposal procedures are possible.

If these are a replacement for LEDs with better properties, these would be widely deployed in everything from lighting to devices. I wonder whether at that scale this presents a safety challenge, given the probability of breaking and the way people dispose things. The glass substrate does hold them in place, but what happens when the glass breaks in all the myriad ways it can in real life?

zakki• 3 years ago

I am just excited as others when reading the TLDR comment. But this warning made me think of do I still want it? Is there anything in the paper explaining about the safety of nano carbon they use?

jiggawatts2• 3 years ago

When there's articles about Gallium arsenide (GaAs) semiconductors, you get the same comments. "Arsenic is a poison!"

Yes, we know. Are you cracking the chips open an licking the semiconductor wafers inside for their flavour? No? Then you have nothing to worry about.

This is the same category of thing. There's micrograms of carbon nanotubes in these lights as a thin-film inside a very strong ceramic casing. Unless you're smashing the thing open and then scraping the surface so you can snort it with a straw like it's cocaine, you'll be fine.

throwaway85034• 3 years ago

Purely as a matter of esoteric interest, does anyone know of any affordable photon counting devices?

CyberDildonics6• 3 years ago

Do you mean a camera?

throwaway85034• 3 years ago

If there's a way to get an integer value on the number of photons per cell in a camera sensor, let me know

acidburnNSA• 3 years ago

Only for high energy photons.

https://gammaspectacular.com/

handsclean• 3 years ago

I think you’re looking for a lux meter. Precision is far rougher than single photons, but good enough for any human-scale use. It’s what you’d use for things like calibrating indoor lighting, quantifying the difference between a sunny day and moonlit night, or testing flashlights. Last I checked a good basic one was under $40.

hammyhavoc• 3 years ago

Lateral thinking through withered technology prevails.

strangeloops85• 3 years ago

This basic idea was demonstrated by some groups at MIT in 2016: https://www.nature.com/articles/nnano.2015.309

MIT news article about it: https://news.mit.edu/2016/nanophotonic-incandescent-light-bu...

I think this paper follows the same basic principle and idea.

adrian_b11• 3 years ago

The MIT article is cited in this research paper and it is likely that it has been the one which inspired the start of this research.

However the progress made from the very primitive device described by MIT and the high-performance prototype made by the Chinese team has been huge.

The Chinese have used completely other materials, which enabled also a long lifetime, not only a better efficiency. There are many new constructive details which contribute to an increased efficiency. The design methodology used by the Chinese for the lossless optical filter is far more advanced and it enabled a much better filter with much less layers.

The MIT article showed an interesting idea, for which it was not clear if it can be successful in practice, while this shows a real device that needs only minor changes in order to become suitable for mass production (e.g. the replacement of HfO2 with TiO2 in the window coating and the replacement of the O-ring used in the prototype with hermetic glass-alumina bonding).

This device could be easily converted into a commercial product in a couple of years.

jiggawatts2• 3 years ago

A yardstick that I like to use for the exponentially increasing pace of technological advancement is the transition from one lighting technology to the next.

Wood fires were the only lighting we could muster for a few hundred thousand years.

Wick-based lighting like candles and oil lamps for a few thousand.

Incandescent electric lighting started about 150 years ago.

Fluorescent lighting about 70 years ago.

CFL lighting about 30 years ago.

LED lighting about 15 years ago.

OLED lighting about 7 years ago.

There's talk now of direct EL nano-rod lighting, this photon recycling thing, and more.

We'll reach a point where new lighting technology is developed faster than the previous lights reach their end-of-life!

A photon-recycling incandescent lighting device

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