Readers might recall I was an early adopter of LED lighting technology. Now it is getting even better.
New LED light design offers less energy, more light
LEDs are durable and save energy. Now researchers have found a way to make LED lamps even more compact while supplying more light than commercially available models. The key to success: transistors made of the semiconductor material gallium nitride.
Incandescent light bulbs are now banned in the EU, while energy-saving lamps remain a bone of contention. In 2016, it will be lights out for halogen bulbs over 10 watts as well. LEDs (light-emitting diodes) therefore have the best chance of becoming the light source of the future. Experts reckon that LED retrofit lamps for use in standard bulb fittings will overtake traditional energy-saving bulbs for the first time from 2015. By 2020 it is predicted that LEDs will have captured between 88 and 90 percent of the lighting market. The tiny diodes offer a whole host of advantages as the most environmentally friendly source of light – they contain no harmful substances, consume less energy and, with a lifetime of between 15,000 and 30,000 hours, last longer than conventional light sources. They also work at full brightness as soon as you flick the switch.
Coping with higher temperatures
LEDs do have one weakness, though – they are extremely sensitive to variations and spikes in power. To function properly, they need a driver that ensures a constant supply of power at all times. This driver, which takes the alternating current from the grid and converts it into direct current with a reduced voltage, has a profound influence on the light yield and lifetime of the LED lamp as a whole. The demands placed on the driver electronics are correspondingly high. This has prompted researchers at the Fraunhofer Institute for Applied Solid State Physics IAF in Freiburg to focus their attention on voltage transformers featuring gallium nitride (GaN) transistors. During practical testing, the scientists found that the drivers developed using this new semiconductor material were extremely robust. Components made of GaN can operate at higher currents, voltages and temperatures than standard silicon transistors. “Heat plays a role both in the brightness and the service life of LED lamps,” says Dr. Michael Kunzer, group manager at Fraunhofer IAF.
Gallium nitride transistors switch at high speed
Gallium nitride transistors can also switch at high frequencies. The switching speed has a significant impact on the size of the coils and condensers built into the drivers for energy storage. In a GaN-based driver, the switch speed can be made as much as a factor of 10 faster than that of its silicon equivalent. “Applied to a smaller surface, this means it is possible to make switching cheaper. The whole LED lamp can be made lighter and more compact while delivering the same or even improved illumination,” explains Kunzer. Since the energy storage component plays a decisive role in manufacturing costs, this could have an extremely positive effect on the end price.
Thanks to the new semiconductor material’s useful properties, Kunzer and his team have been able to boost the efficiency of the GaN driver to 86 percent – between one and four percentage points better than its silicon equivalent. When compared with the silicon transistor LED lamps available on the market., the scientists were able to increase the light output: while the luminous flux of commercial LED retrofit lamps featuring silicon components is around 1000 lumen (the unit used to measure the light produced), researchers from the IAF have been successful in increasing this to 2090 lumen. “20 percent of energy consumption worldwide can be attributed to lighting, so it’s an area where savings are particularly worthwhile. One shouldn’t underestimate the role played by the efficiency of LED drivers, as this is key to saving energy. In principle, the higher the light yield and efficiency, the lower energy consumption is. If you think that by 2020 LEDs will have carved out a market share of almost 90 percent, then it is obvious that they play a significant role in protecting our environment,” says Kunzer. The researchers will be showcasing a demonstrator of their retrofit LED from April 7-11 at the Hannover Messe, where they can be found at the joint Fraunhofer booth in Hall 2, Booth D18.
Speed: You are likely right about the translation, except that I think what was translated is what wasn’t clear; the translation may be fine.
The passage I mentioned tends to reinforce a notion that some commenters seem to have taken. Specifically, the post seems to imply that, in contrast to incandescents, LEDs are like computers in that they need to avoid power-supply interruptions . As far as I know, though, the greatest storage required by LEDs but not incandescents is only the amount required to bridge the 8-10 msec between grid (mains) half cycles. (I’ve been told that incandescents’ filaments do that nicely, thank you.)
Now, my guess is that this does mean tenths of a joule–maybe tens of microfarads–for a single LED lamp. But this is orders of magnitude less than keeping the lamp powered for human-scale durations. On the other hand, it is much greater than I would have thought required for voltage transforming, which my guess is what the gallium-nitride-switching-speed comments are directed to.
So, for all I can get from the post, using gallium-nitride transistors affects only the amount of storage in a part of the operation that itself is only a minor part of the overall storage requirement.
Sam Grove: “Double the frequency and you will double the number of intervals storing half the energy, so the total energy stored over time is the same. Doubling the frequency allows the use of smaller caps and coils which not only cost less, but take up less space.”
I’m not sure I 100% agree with your physics, there. It’s true that for transforming purposes increasing the frequency can lead to smaller inductors and/or capacitors. But doubling the frequency with which you energize and de-energize a given capacitance or inductance to and from a given voltage or current does not increase that capacitance’s or inductance’s average energy storage.
The point is that the higher frequency enables the transforming to be done with less energy storage, not that the same energy is stored by smaller components.
And, as I mentioned above to Speed, I still don’t see how this affects overall energy-storage requirements significantly anyway; I don’t see how switching fast reduces the energy storage required to bridge power-grid cycles.
Yep, you can keep your health care plan and your light bulbs. Just don’t bring up the subject of costs. Gee I wonder if anyone bothered to check the CPI price change and item swap in that inflation survey. I guess we just chalk it up to involuntary change in cost of living and not inflation.
We tried some of the twisty cfl bulbs in our house years ago, mainly because of the children leaving lights on all the time. I had even reported a fire with those bulbs on this blog a while back. Since then I have tried some of the LED bulbs and have been very much pleased with them. I can only imagine that things will get better from here. I still firmly believe that the outlawing of the traditional bulb was criminal.
John Innes says: March 12, 2014 at 6:46 am “Regarding incandescent lights lasting longer if dimmed, the rough rule of thumb is that, for each 2% reduction of operating voltage, the life is doubled.”
Basically, that’s the idea behind “extended life” light bulbs, they are just bulbs designed to run at a higher voltage so ~115 A/C is already a cooler “dimmed’ voltage condition. They are also therefore less efficacious and more yellow in color as a result. The most efficacious filaments are the hottest and have the shortest life, (such as photo flood light bulbs) .
Another major failure factor for incandescent filament failure is initial inrush current at start up which is roughly 10X the operating current. For a 100W bulb, the first full A/C cycle is pushing something like 10 amperes. The rapid thermal expansion from that puts a tremendous mechanical shock on the filament producing vibration/strain induced cracks on the surface that ultimately get deeper every time you flip the switch on. Those cracks also reduce the cross section thus locally increasing the amperage/area resulting in an even hotter condition at the cracks, (and weaker as well), that accelerates their propagation.
So, not only run the bulbs at a reduced voltage – ramp them up with a lamp dimmer control and they’ll last even longer.
“Box of Rocks” was the localhost name of my last desktop computer, for all of the clever little dopey silicon rocks in it.
Chuckles…
I on the other hand get the moniker from the idea from my US Navy ‘A’ school – AX that some folks are as dumb as a “box of rocks” and can not be taught anyhtingie….
@Cynic
Thanks for the Jevons Paradox reminder.
commieBob: It is nice to meet a fellow oldtimer. Live long and prosper.
I don’t know where else to complain so… is it me or are there some LED automobile tail lights out there that are ridiculously too bright and basically blind you if you are stuck behind one at night at a intersection? Has DOT anything to say about the spot intensity factor of automotive LED’s?
Another thing is that some appear to be operating on some sort of low frequency switching regulator circuit that causes, especially at night, a strobed trail of ghost spots across your retina whenever you move your eyes.
I have no problem with technical advances. I just want to point out that there is not any energy being saved. Any energy being saved on lighting just goes somewhere else. The governments have been passing energy saving regulations for forty years and yet there are no huge piles of saved energy in any form. It’s basic rule that the economy will burn all the energy produced. No energy has been saved and there are no laws even being considered to mandate saving energy. Saving energy would mean putting X barrels of oil or Y tons of coal aside and not being allowing to use it. Taxing energy doesn’t save any energy. Taxing energy is like taxing the blood going through your veins. If you want to live you pay the tax but the blood can’t stop moving. In the government regulation game there are winners and losers, but no energy is being saved. The flows of energy may just be directed somewhere else. If I am saving X energy on lightning I might just use it to keep my house more comfortable. One degree on my thermostat probably blows away all my energy “savings” caused by government regulations. If I don’t burn the “savings” somebody else will.
I have been using LEDs in my entire house for up to 4 years, now. They are all warm white and provide a slightly whiter light. You only need to look on the package, now, to make a choice of bluish sunlight-type output, or warm white. The most reliable bulbs have turned out to be made by Philips. Most of them use either a single large or several medium sized light emitting surfaces. Anything containing multiple less is a cheap ripoff. The incandescent bulbs for sale before the U.S. ban on manufacture tended to blow out after 6 months and the CFL’s were little better. A broken CFL is a hazmat situation and there is evidence that exposure to the extreme UV output may interfere with your ability to fall asleep.
There is no evidence that there are any ill effects from long exposure to LEDs. In addition, outdoors the warm white bulbs attract a fraction of the insects that CFLs and incandescent bulbs do in southern Arizona.
I changed over to CREE LEDs for my high use lighting and some hard to access lights. Home Depot for $6.95 on sale. In my favorite reading lamp I have two 800 lm bulbs.
@lighthouse
Thanks for the info. I didn’t believe the MTBF numbers quoted for the LED’s or CFL’s, and you have strengthened my doubts.
I personally like LEDs, but have learned to put up with the reality that they don’t last as long as incandescent bulbs. One of the expenses I hate is that some of the companies from a few years ago no longer exist. When I have an array of bulbs (like in bathroom vanities), and one goes out, I can’t get a replacement just like the old one, so I have to buy a whole new set. The warranties are worthless if the company disappears. Still, I don’t know what I did with the old incandescents, and we hated the CFLs – ugly and weird lighting characteristics.
If they can only get the reliability up there, I would be truly satisfied. (I don’t want to open up and re-solder LEDs, if that is really possible!)
Bought six 90 watt equivalent LED spots for my kitchen @ur momisugly $39.95 ea. one year ago. So far 4 of them have failed. I seriously question their long term economy which has been the benefit hawked.
Is there enough economically-extractable gallium in the world to keep advanced LED’s at the top in the lighting pecking order? Or, when we finally reach “energy nirvana” and electricity becomes cheap again, will tungsten bulbs make a comeback???? Stay tuned…
“… [LED] the most environmentally friendly source of light … ”
———
Wait until the enviro-grievance groups find out that manufacture of LEDs and Gallium Nitride transistors require:
– freight train loads of ammonia & hydrogen gasses.
– multi-megawatt electricity consumption by the semiconductor manufacturing facilities, most likely supplied by coal burning plants.
My experience is that long lifetime for LED is a blatant lie, a year ago or so I changed from halogen to LED’s in a 3-bulb celing fixture in the dayroom of my flat , the halos had 35w power rating gave a nice warm soft white color to the room , so I went for 4w warm white LED’s , the light color from them was little harsher, but not so much that it bothered me, and the brighness was on par with what I was used to from the halogens, so I was resonably happy with the change, but not for long , whithin five days the first of the new bulbs went haywire , and stated to bink like feew**ng ’80- style disce danceroom lamp, so I pulled it out , went to store where it was bought, and demanded a new one free of charge , on the groundt that it must have been a defective item when they sold it to me, because had only lasted all fo 30 hours of use , not the stated 10000. The store chief hewed and hummed a little and was fairly relunctant to do so but relented in the end. So I put the new led in and everything was okay for some 8-10 days , then the new led simply died ( after 40-60 hrs use ) , Well I did nother bother to try to get another free replace as the my word exchange with store personnel had been on the verge of turning ugly in the first instance, so I just pulled the dead bulb out , and decided to live with the two still going for a while to see if they lasted longer, and wonder of wonders both died within a 4 week from that. Ok I thought, those LED bulbs were a comparatively cheap Chinese brand to begin with and perchance were just “China quality” junk , let’s give it another try. But to be on the safe side I asked a friend who is a certified electrician to come around an check if there was something wrong whith the light fixture, he di so found nothing amiss and also brougth me three new top of the range ( both in price and brand rating = SIEMENS ) 2.5w LED’s and put them in. The light from them was a bit more to the blue end of color scale ( bright white ), and to tell the truth I found the illumination from them somewhat uncomfortable, with the result that for a while i only turned the overhead light on for short periods of time , and made do with the wall lights and a couple of reading lamps for daily use the next few weeks, intending to replace those LEDs again for a set with a more pleasant color temperature. But alas I never got around to do that , wihin a couple of months all three of the new LEDs had turned up their toes and retired to greenie paradise or wherever else such thing go in their afterlive, and I had replugged the perfectly good halogens that I orginally took aout of the fixture again. And there they shall stay , even if they draw 8-10 times the power a LED does, and if they die I will most likely replace them with the same type , I have already bought and stowed a batch 30 spares, which should be enough to last a couple of decades as those that are now in use are already somewhere above the 3000 hour mark of in use ( c.a 2 years worth of illumination ) .
What the heck. I’ll throw my 2 cents worth in too.
Incandescent bulbs. Little difference between them. You could buy any of them and pretty much know what you were getting in terms of light.
CFLs and LEDs? With all the different shapes, styles, etc it can be an expensive gamble. No store will ever use all of the multitude styles and shapes with in store displays so that you have an idea what they look like. I can’t afford to try, try again.
LED Christmas lights suck. Sorry. Hot spots and uneven lighting. What is needed are REAL C7 and C9 ceramic coated GLASS with LEDs inside. Home Depot sells a Cree LED bulb made with frosted glass. I’m waiting for Cree to do this with Christmas lights.
I even did a PowerPoint on the pros and cons of different Christmas lights since I help with my cities Christmas parade. It is a lighted night time parade and some of the entrants meet the minimum number of lights required but are pathetic to look at. Here is a link to the PowerPoint if anyone is interested.
https://www.dropbox.com/s/73ebwwk5ahm9ua9/CHRISTMAS%20LIGHTS.pptx
Just fitted out my whole house with100% LEDs – been running some of them for 3 to 4 months intermittently during last stages of fit out – moved in 2 months ago – not one light has failed, flickered or caused problems – dont know what you are all whinging about. Mix of warm white with bright white – can vary the balance to whatever we need. I am sold…
No whining. 3-4 months is the lifetime of a large candle. I just don’t believe the MTBF numbers by the LED manufacturers. Experience with CFL has already told me the MTBF claims are inflated.
Add the fact the components are largely made in China doesn’t give me warm fuzzy feelings.
But doubling the frequency with which you energize and de-energize a given capacitance or inductance to and from a given voltage or current does not increase that capacitance’s or inductance’s average energy storage.”
It’s like using a larger or smaller bucket. To deliver the same amount of water in a given period of time, the smaller bucket must be filled and dumped at a higher rate. That’s why a 60Hz transformer delivering X Watts of power can be replaced with a much smaller transformer driven at a much higher frequency, The filtering caps can be smaller as well because only have to
hold power for a fraction of the time required by line frequency transformers
gping from 80% to 85% doesnt make your lamp a whole lot brighter for the same power, but what it does allow you to do is run it at 50% more power for the same heat..and that is relevant.
In short a totally confusing article.
1/. Incandescent lamps are not banned. I’ve got well over 100 I bought this year.
2/. increased switching speed of LEDS is irrelevant for lighting purposes: what we want is steady light not a gigabit fibre optic driver.
3/. Increased switching speeds for down conversion from line voltage is good. That does shrink the electronics somewhat, but that’s nothing to do with the LEDS.
4/. Its not clear either that LED bulbs actually use switched transformers. Many seem to be a lot cruder than that.