Raising the efficiency bar in light fixtures: going beyond LED’s efficiency
January 7, 2010 § Leave a comment
Global warming is these days on most environmentally conscious people’s lips. And is perhaps the most dangerous thing to happen that is caused by human recklessness. Scientists agree that it is happening and every day new reports suggest that each time scientists have been outpaced by the speed of events.
Here on perfectcube you are well aware of the efficient materials and products that are able to slow down the CO2 emissions by consuming less energy, requiring less maintenance, having great design, thus keeping them longer in your homes before something better looking sets into your hearts and of course having less or none toxic waste to get into the water supplies or building landfills into mountains.
Today I am going to speak about energy-efficient light, perhaps the most important companion of our evolution. It was a trading currency for more daily time, allowing equally bright minds to discover and build a better world.
Nowadays we are witnessing the going to obsolence of the incandescent light bulb, although recent struggles showed that we can squeeze more light of the century old and still most common and un-changed product design. Fortunately there are better choices there.
Available as mass produced – cost effective solutions, e CFLs came to low enough prices to be embraced by the public. But they pose environmental threats as they contain liquid mercury, a hazardous metal that is very toxic and accumulates in live organisms. Also they are plagued by the short lives (better than incandescents though), even shorter if the light is switched on/off repeatedly, older ones are not dimmable, they take time to warm up highest light output and replacing the bulb implies throwing the electronic ballast away even if flawless making it an unefficient design. This recently got solved by some manufacturers making the glass tube replaceable while keeping the ballast. Also the high toxicity of the liquid mercury inside usual CFLs has been solved with some manufacturers using solid amalgam pills of mercury in alloy with other metals to render it harmless if broken (still needs to be disposed of properly and recicled as many years in the landfills will still leak mercury out of the pill). Two big score points if widely adopted but the warm-up time and it’s inability to be used with motion sensors, as frequent switching alters the lifespan of the bulb – the advice is that the CFL bulb is not turned off unless 15 minutes has passed to keep the advertised lifespan- make it a pretty poor choice for me, even if it is very affordable.
Still, more efficient light sources exist, most common being the LEDs.Almost flawless at first sight, they produce lots of heat at high outputs requiring complex and expensive heat sinks.They are also unidirectional, the manufacturing process is lacking in the eco-friendlyness department and are still very expensive. Even if over their lifetime the saving in energy is way greater than their initial cost and they can pay for themselves in a few years (compared to several years of lifespan, some claiming even 25 years). Getting costs to CFL comparable price, as promised by some, might encourage people making the switch from CFLs sooner than expected. But we aren’t there yet.
On par or even better than LEDs (as claimed by articles and companies)are induction lamps, which are probably less known as energy efficient light sources by the general public. They are most commonly used in the street/tunnel lighting or large facilities where motion sensors will switch on/off the light virtually with
no altering of the lifespan or light quality of the lamp. They work the same way as CFLs but the internal electrodes that are inducing light emission are replaced by external electromagnetic radiation, thus making the light source an enclosed environment where nothing interferes, no metal electrodes that can react with the gas inside.
Pretty similar with how the keep-ballast-replace-tube-only CFLs work if it wasn’t for greater energy conversion efficiency (they say better than the mighty LEDs) and huge lifespans (80-100000 hours compared to 50-55000 for commercially available LEDs). Replace the liquid mercury with an amalgam pill and you’ve got a winner (the ibuyinductionlighting sell the bulb pictured on the right).
The plasma lamps are the newcomers (as of 2009) in this field. They also operate electrod-lessly by means of radio waves that excite a noble gas. They can produce some 140 Lumens per watt, outpacing both LEDs and induction lamps by huge margin. Commercially available for high energy applications (where the technology is cost effective), they won’t enter soon the household market.
ESL (electron stimulated luminescence) seems to me one heck of alternative to the disadvantages of both CFLs and LEDs. It’s currently 4 times as efficient as incandescent light bulbs, has no mercury, is instant-on/ instant-off, it can be turned on at any brightness without delay, is turning electrons directly into light without intermediate chemicals and produces the closest color to incandescent bulbs. It uses a proprietary luminescent coating that is beamed with electrons to produce light. They are as lasting as normal CFL (around 6000 hours and have an light output of 40Lm/W. Vu1 is the manufacturer of the proprietary luminescent coating and their ESL bulb would be around $20 when it hits the market, according to spokesman James Quick, which is about half of the price of current LED bulbs (Philips Master, GeoBulb and Pharox LED Bulb). Vu1 might market the bulb in mid-2010 if its funding holds up. It plans to begin manufacturing at its EU plant by the end of this year. I sure expect them to be as cheap as CFL or otherwise they won’t catch.
One so young light source that as far as I know isn’t yet even out of the lab is microcavity plasma lamps. They are essentially arrays of micro cavities usually within an aluminium-dielectric(aluminium oxide /sapphire) sandwich, filled with gas. This panel is covered by a phosphor-coated inner side glass. The microcavity plasma arrays don’t yet compare with the above mentioned light sources in terms of light output but this is a work in progress as one of the youngest technologies in illuminating technology and things are only to get better. The strongest point so far about microcavity plasma arrays is that they don’t need ballast electronics (this means low costs) and the possibility of making large panels of virtually any shape to behave like lamps. This has huge architectural/design implications and could take the product design industry by storm when it comes out of the oven.
One last light emitting device that was an accidental discovery is cuantum dots luminiscence in warm white spectrum. These quantum dots are crystals of cadmium and selenium that contain either 33 or 34 pairs of atoms, which happens to be a preffered size the crystals grow. Thats’s why it is possible to create such small nano-scale crystals even though they are less than half the size of normal quantum dots. Coating LEDs -which usually give a white-bluish sharp light- with a solution of such crystals makes it glow a warm white light emitted by the quantum dots when excited by the LED’s light, whatever colour that might be. An interesting and logical development of the technology is making the quantum dots glow under electricity flow instead of intermediate light. This will skip one expensive step of actually producing a light source than use that one to power another technology which makes the process too complex and unnecessarily redundant.
I personally totally subscribe to having quantum dots coated led-arrays in my home. Just waiting for it to happen (until then CFLs seems a reasonable choice, perhaps some ESL when the price will go under $10 and life will get to at least 10000 hours). Until then, it all boils down to where the industry puts its money because scale is be the only thing that will bring the costs down so that a shift in what people buy can happen. And, so far, it seems that LED is the winning technology.
That’s all so far for this article, I will add over the next days pictures and links so come back soon or even better subscribe for email news on the right panel below the website header.
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