Great, just great. Don’t get me wrong, I like the LED bulbs, I have several in my house. But when we get back to basics, a tungsten light bulb doesn’t require a haz-mat squad to dispose of. It’s glass, ceramic, tungsten, some thin steel, and tin solder (if ROHS). CFL bulbs and now LED bulbs are so much more eco unfriendly and when they inevitably end up in landfills, they become a source of heavy metal. We may have gained short term energy efficiency, but the long term payback may not be worth it.
LED products billed as eco-friendly contain toxic metals, study finds
UC researchers tested holiday bulbs, traffic lights and car beams
From UC Irvine:
Those light-emitting diodes marketed as safe, environmentally preferable alternatives to traditional lightbulbs actually contain lead, arsenic and a dozen other potentially hazardous substances, according to newly published research.
“LEDs are touted as the next generation of lighting. But as we try to find better products that do not deplete energy resources or contribute to global warming, we have to be vigilant about the toxicity hazards of those marketed as replacements,” said Oladele Ogunseitan, chair of UC Irvine’s Department of Population Health & Disease Prevention.
He and fellow scientists at UCI and UC Davis crunched, leached and measured the tiny, multicolored lightbulbs sold in Christmas strands; red, yellow and green traffic lights; and automobile headlights and brake lights. Their findings? Low-intensity red lights contained up to eight times the amount of lead allowed under California law, but in general, high-intensity, brighter bulbs had more contaminants than lower ones. White bulbs copntained the least lead, but had high levels of nickel.
“We find the low-intensity red LEDs exhibit significant cancer and noncancer potentials due to the high content of arsenic and lead,” the team wrote in the January 2011 issue of Environmental Science & Technology, referring to the holiday lights. Results from the larger lighting products will be published later, but according to Ogunseitan, “it’s more of the same.”
Lead, arsenic and many additional metals discovered in the bulbs or their related parts have been linked in hundreds of studies to different cancers, neurological damage, kidney disease, hypertension, skin rashes and other illnesses. The copper used in some LEDs also poses an ecological threat to fish, rivers and lakes.
Ogunseitan said that breaking a single light and breathing fumes would not automatically cause cancer, but could be a tipping point on top of chronic exposure to another carcinogen. And – noting that lead tastes sweet – he warned that small children could be harmed if they mistake the bright lights for candy.
Risks are present in all parts of the lights and at every stage during production, use and disposal, the study found. Consumers, manufacturers and first responders to accident scenes ought to be aware of this, Ogunseitan said. When bulbs break at home, residents should sweep them up with a special broom while wearing gloves and a mask, he advised. Crews dispatched to clean up car crashes or broken traffic fixtures should don protective gear and handle the material as hazardous waste. Currently, LEDs are not classified as toxic and are disposed of in regular landfills. Ogunseitan has forwarded the study results to California and federal health regulators.
He cites LEDs as a perfect example of the need to mandate product replacement testing. The diodes are widely hailed as safer than compact fluorescent bulbs, which contain dangerous mercury. But, he said, they weren’t properly tested for potential environmental health impacts before being marketed as the preferred alternative to inefficient incandescent bulbs, now being phased out under California law. A long-planned state regulation originally set to take effect Jan. 1 would have required advance testing of such replacement products. But it was opposed by industry groups, a less stringent version was substituted, and Gov. Arnold Schwarzenegger placed the law on hold days before he left office.
“I’m frustrated, but the work continues,” said Ogunseitan, a member of the state Department of Toxic Substances Control’s Green Ribbon Science Panel. He said makers of LEDs and other items could easily reduce chemical concentrations or redesign them with truly safer materials. “Every day we don’t have a law that says you cannot replace an unsafe product with another unsafe product, we’re putting people’s lives at risk,” he said. “And it’s a preventable risk.”
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I am curious to know what happens to used CFLs once disposed of. How exactly are they treated when returned to the shop/recycle centre. Since they contain mercury etc they must surely be handled with great care. Is the mercury reused. Where do they finally end up?
George E. Smith says:
I stand corrected.
And I agree, challenges will always be met, the white LED will revolutionize all aspects of illumination, more than most people will ever probably be consciously aware of. The cheap 10c white LEDs I got from china were great… for about 5 hours, after which they tinged blue and faded to almost no visible light. I also have a white LED night light downstairs that’s been going strong for years with no visible degradation.
I look forward to self-illuminating ceiling and wall panels, soft ambient lighting with adjustable colors, all the possibilities that a cold, safe LED light can provide.
CFLs, on the other hand, are a complete waste of effort in almost every way. I despise the light quality, the complexity, the materials usage, the flickering, the sound, everything. They’re ugly and harmful. How could anyone possibly support replacing incandescent bulbs with these things???
“I have lived here in Minnesota all my life and never heard anyone call regular light bulbs “heat globes”.”
I am sorry the humor went over your head.
While I don’t wouldn’t wish to dissuade anyone from doing experiments and taking measurements, I do wonder if the researchers discussed their concerns about “toxic” LEDs with the Electrical Engineering Faculty at UC Irving? I’m sure they could have provided their colleagues with a list of materials used in LEDs and saved them from a lot of work.
Will this group of researchers also grind up their computers, cell phones and other personal electronics and inform the public of the “toxic” content of these devices? I need to know if dropping my laptop will release a cloud of “toxic” vapor. /sarc rant off
Don’t worry about kids eating LEDs though, they’re too busy eating microchips…
“Ogunseitan said that breaking a single light and breathing fumes would not automatically cause cancer, but could be a tipping point on top of chronic exposure to another carcinogen. And – noting that lead tastes sweet – he warned that small children could be harmed if they mistake the bright lights for candy.”
Holy mother of Bozo! If I see the phrase, “tipping point” one more time, I’m going to scream.
And how far do people have to reach to rationalize something to come up with something as stupid as children mistaking bright Christmas lights for candy.
“”””” Calvi36 says:
February 11, 2011 at 2:35 pm
Damn, George E. Smith, where do you find this stuff, my head hurts now! Just joking, it’s all good info. “””””
Who said anything about “finding”. How about “knowing” ?
I first got my feet wet in LEDs in 1965, at Monsanto corp Central Research labs in St Louis Mo. For them it was a few million dollars of exotic materials business; namely the III-V semiconductoir materials from which most LEDs are made. I actually first got involved doing Optics for packaging; but then later on doing driver circuits for red laser diodes. Monsanto had red GaASP laser diodes in 1966; but they only worked at liquid nitrogen temperatures, and at very high current densities. Try making a 100 Amp peak current pulse that is only 100 nsec wide (or the laser would melt. The laser chips were about5 mils wide and thick, and maybe 20-30 mils long, so astronomical current densities.
The original work on the GaAsP led system came out of the University of Illinois in Urbana under the eye of Professor Nick Holonyak; who in my view, is the most deserving candidate; who has not yet won a Nobel Physics prize. His students now staff the labs at places like Cree Research and Phillips Lumileds; Lincoln Labs, and some other Eastern folks.
Later on I got into an LED startup company, which at one time was the largest company in the world in LEDS; but we never had any equity funding; financed it out of our own pockets. In the heyday of the LED display hand held calculator, we had 72 crystal growing furnaces, making GaAs crystals about every three days, using the Gradient Freeze, Horizontal Bridgeman method of simultaneous synthesis and crystal growth. Each ingot weighed about 700 grams; and the profit from the sale of that material paid completely for the capital cost of the whole furnace. We were about to gear up to 144 furnaces (which we also built ourselves), when I made a breakthrough in snap on (non-immersed magnifier lens optics, which about doebled the viewing angle and allowed higher magnifiation. That crashed the need for more bigger monolithic LED chips; so we scrapped the expansion plans. In the gradient freeze process, you have to raise one end of the furnace (the colder end where the seed crystal was) while you heat up the ingrediants, and synthesize the Ga AS from 7-9s purity Arsenic and gallium. Then you lower the end, so the molten GaAS finally touches the end of the seed crystal, which is at one end of the Quartz boat, resting on powdered quartz sand. the you start lowering the Temperature slowly over 2 1/2 days, so that the crystal grows from the seed as the freezing zone moves along the crystal. To jack the end of the furnace up, and lower it again, we used ordinary scissors jackls from Sears Roebuck nearby. Like I say; we built the whole shebang oursleves, and also built our own Epitaxial GaAsP deposition reactors; including building the controllers for all of that. To lower the Temperature slowly on the crystal furnaces, we used an ordinary silicon diffusion furnace controller, whcih cost about $300, and we mounted a $7 Synchron clock timer motor on the front panel which was used to belt drive the ten turn helipot dial that turned the set point temperature down.
Monsanto used a $35,000 computer controlelr to do the same task as our 47 motor, which is why they thought we had one epi reactor and mayb four crystal growers; whereas we had 16 epi reactors, and 72 crystal furnaces; all of which we built ourselves.
We lost our market edge when the game shifted from GaAs substrates to Gallium Phosphide because we couldn’t afford that 1/2 million dollar high pressure bomb needed to grow GaP. We finally got out of it around 1980 with the remains becoming part of Siemens corp.
It was in 1966, maybe 67 while I was still doing the opticvs at Monsanto, that IBM developed the silicon doped liquid epi high efficiency gaAs infra red process. I desinged an optical package for that device to go into a card reader that IBM wanted.
It’s a very diferent game today. we used to turn out the room lights and look through a microscope to see the dull red glow coming from a piece of a wafer. Now they have to conform to some LED specific radiation hazards (eye exposure) requirements.
The AlInGap yellow ones are spectacularly bright; and that is the hardest color to make, since it goes from grellow to gold in only 5 nm wavelength change.
The future application of LEDs will be different from current lighting; to exploit the properties of LEDS’
And they are not likely to poison your neighbor’s cat.
Illogical thinking over the misguided anthropogenic CO2 driven global warming thesis is illustrated by the advocacy of the low energy light bulb as a means to reduce energy consumption.
As a heating engineer, this is subject that I have a professional knowledge about. When we calculate a cooling load for a building we combine the total heat input into the building, the occupants, the electrical appliances including the lighting and the solar gain these inputs all combine to create the cooling requirement, in this case low energy lighting is a logical selection.
However in the Northern Hemisphere the major use of our domestic lighting coincides with our domestic heating requirements and as such incandescent light bulbs make little or no difference to the energy used. This is because with modern heating control, typically thermostatic radiator valves; the heating system is closely regulated to the heating requirement of the occupied space.
The heating requirement for any space is a function of the heat input to the space, the required space temperature, the heat loss through the structure and the external ambient temperature. Therefore if it takes 1kw to heat a space this might come from the occupants (assuming 2 people) 2x90watts – the heat from incandescent lighting 4x 20watts (assuming 4 x 40 watt bulbs) and 740 watts from the heating. If the lighting is then changed to low energy bulbs the equation is changed and becomes, the occupants 2x90watts – the low energy lighting 4x 0watts, requiring 820 watts to be supplied from the heating, has any energy been saved? NO
All that has been acheived is move the energy usage from one system to another ie from the electricity bill and onto the gas / oil bill.
Peter (commenting on my spray about lack of LEAD in a LED):
I’m well aware of the ROHS directive. LEDs for domestic and industrial lighting do not qualify for the exemptions, including the solder used for assembly of the the LED onto whatever else. Flight control systems and medical devices, perhaps. Some infrastructure, maybe. But domestic stuff, no. The ROHS directive applies across the board, not just to electronic components. So the stuff the components are assembled into (the next higher level assembly… and so on up through to the finished product).
————–
Angry Exile (and others) re the Halogen lamps: The more modern halogens don’t have so many problems as they used to. Its a good idea if you dim them, to run them at full brightness now and again. But even then with modern ones, its not such a big deal.
————–
Jeff Alberts:
I have been using CFLs for over 15 years (they do save me money on my power bill, and did even when I was paying $10 each for them). I have taken to writing the installation date on the base of each lamp when it goes in, and have done this for 10 years now. My observations are that the lamp quality has decreased as they became mandatory and the prices went down (volumes shipped went up). The claimed lifetime of about 3-5 x that of incandescent (ie about up to 5000 hours) is generally not met. I do have one lamp which is now so dim its close to useless but its the freak – it has been used for about 5-8 hours every day for well over 6 years. The norm, though, is that they last about 12 months, which in running hours is about 2000 hours. Not what is claimed at all. I have also had the CFLs explode when turned on, shattering glass and muck all over the floor. A quick poll at a meeting of lighting engineers revealed about 30% of the participants have had something similar. They are built to a price, and you get what you pay for.
“”””” Billy Liar says:
February 11, 2011 at 2:10 pm
bubbagyro says:
February 11, 2011 at 10:56 am
From Wiki:
White LEDs can also be made by coating near ultraviolet (NUV) emitting LEDs with a mixture of high efficiency europium-based red and blue emitting phosphors plus green emitting copper and aluminium doped zinc sulfide (ZnS:Cu, Al).
Gasp! “””””
There’s a problem with the near UV LED approach, and CFLs have the same problem. Both of those have to first produce the short wavelength UV radiation, that gets absorbed by the Phosphor; so instead of making a 460-470 nm blue photon which is an efficient part of a white light spectrum, you have to create a higher photon energy UV photon. when that excites the phosphor, the diffence in photon energy is lsot as heat; so you prefer to have the blue photon as close to the desired blue component as possible.
Of course these other systmes were developed to try and get around the Nichia Patents on the Cerium Yag phosphor.
But the whole thing is somewhat materials constrained; and for beauroidiots to complain that the components are toxic, is stupid.
Tell them to come up with a replacement for Oxygen for us to breathe so we don’t get Oxygen poisoning when we dive deep on ordinary air.
I routinely tell all the green weenies at the whole foods, and organic food stores that they shouldn’t eat organic foods, because they all have carbon in them; which is toxic.
CFLs are a fire hazard.
The wasted energy of incondesent bulbs is the portion that creates heat as opposed to light. If the heater is on, incendesent bulbs are essentially 100% efficient. This gets no attention. The Northern Europeans have no reason to use these bulbs on an energy efficiency basis.
I wanted to try a few LEDs to replace my 60 watt incandescent bulbs outside, but I couldn’t find any that looked like they were made for that function. And they are expensive.
And a little bit of OT. In Germany they call light bulbs “gluhbirne” (with an umlaut over the u). That means “glowing pear”.
I agree that this is just chemophobia.
However, here’s an interesting alternative: Electron Stimulated Luminescence – ESL
http://www.vu1corporation.com/technology/
(Not affiliated with the company or product, just found it interesting.)
Many states have their own “safe” level for mercury contamination, something around 300 billionths of a gram per cubic meter. One CFL breaking in your house is 6 times that amont of contamination.
Another source says that the mercury level is 300 times safety standards:
Breaking a single compact fluorescent bulb on the floor can spike mercury vapor levels in a room – particularly at a child’s height – to over 300 times the EPA’s standard accepted safety level.
Furthermore, for days after a CFL has been broken, vacuuming or simply crawling across a carpeted floor where the bulb was broken can cause mercury vapor levels to shoot back upwards of 100 times the accepted level of safety.
Following the study, the Maine DEP made eight new recommendations for usage and cleanup of CFLs, including the recommendation to not even use the bulbs in carpeted rooms where children, infants or pregnant women live. The likelihood of breakage, near impossibility of cleanup and risk of prolonged exposure, the study concluded, are just too great.
Read more: 1 broken bulb pushes contamination to 300 times EPA limits http://www.wnd.com/?pageId=72133#ixzz1DiwctQbY
I will only mention three interesting articles.
1. http://www.dailymail.co.uk/health/article-1340938/Eco-bulbs-health-hazard-babies-pregnant-women-mercury-inside.html
The Health Protection Agency [UK Government] says a broken CFL is unlikely to cause health problems. However, it advises people to ventilate a room where a light has smashed and evacuate it for 15 minutes.
Householders are also advised to wear protective gloves while wiping the area of the break with a damp cloth and picking up fragments of glass. The cloth and glass should be placed in a plastic bag and sealed.
CFLs are not supposed to be put in the dustbin, whether broken or intact, but taken as hazardous waste to a recycling centre.
Does every user know and practise these prescriptions?
2. http://notrickszone.com/2010/11/23/green-police-orders-confiscation-of-enviro-contraband/
Recently, the two German engineers quickly sold 4000 of the climate-killing bulbs as “heat balls”, and so they ordered up another 40,000 pieces from China. To get them through German customs, they declared the bulbs as “heat balls” – miniature heaters that could be powered by a standard fluorescent light bulb fixture.
Read the reaction of the Department of Environment!
3. A summary of the health effects of LEDs: http://www.afssa.fr/Documents/PRES2010CPA14EN.pdf
What are the risks of the artificial light of LEDs for our health?
I’m not a fan of CFLs. Cities want people to trade mercury thermometers in for digital, and then green expos push boxes of CFLs.
For emergency supplies I’m planning on olive oil burners in handled mason jars- a fuel I can dip my bread into in the meantime. I’m also waiting for Humdinger to market their turbineless windbelts (using aeroelastic flutter) for home use. An application of windbelts that I haven’t heard discussed yet, that I think would be ideal in a power outage, is if the blower fan would power it’s own battery backup. Please, someone create this product.
In producing light from electricity, measured in lumens/watt, the BEST high brightness white LEDs are about 50% more efficient than a fluorescent tube, CFL or straight line. They also cost many times more on a lumen/$ basis. Fluorescent tubes are about four times more efficient than an equivalent light output incandescent light bulb. A halogen bulb is 15% or so more efficient than an incandescent, mainly because they run the filament hotter.
ALL florescent tubes contain mercury – it is required to generate the ionized mercury vapor gas that generates the UV light that hits the phosphors which then makes the white light. The amount of mercury in a GOOD CFL is less than what is in an average size amalgamated mercury filling in one of your teeth. I don’t know how much is in a 4 or 8 foot tube but since they are physically much bigger and higher wattage I would guess they have more. However, they’ve been around for 50 years or so and there never was a “mercury scare” and they break a lot easier when dropping one than a CFL does . Cheap (Chinese) CFLs usually have more mercury, sometimes 4-5 times as much, than a CFL made by a major and reputable MFR like Philips – even if they are made in China too.
Turning any fluorescent light on and off shortens the light of the fixture. It is not so much a problem with the bulb but the electronics. The ubiquitous 75W incandescent draws 75W of power when operating but since the tungsten filament has a positive temperature coefficient the resistance is lower when cold and thus when it is first turned on the peak in-rush is about 700W (about 7A @ur momisugly 120VAC operation) . That’s why incandescent bulbs almost always burn out with a FLASH when first turned on.
Fluorescent lights also have an in-rush current but it is in the electronic control, called a ballast. The in-rush in a ballast comes from charging up the input filter capacitor on the AC side. It is limited some what by a negative temperature coefficient thermistor on the AC input that has higher resistance when cold.
The big fluorescent lights have ballasts made by Philips (Advance)., GE and other MFRs who, for the most part, know how to make a reliable ballast. There isn’t much room in a CFL for the ballast and they are low cost so their ballasts simply just aren’t as good and they use a smaller (and cheaper) rated thermistor that doesn’t limit the in-rush current as much. As a result they may have an in-rush in the 30 -50A range with a 120VAC input. Double that for a 230VAC light. The in-rush is hard on the electrolytic input capacitor which is already the number 1 failure component in the ballast. Put an even cheaper, lower quality capacitor out there and the CFLs will fail a lot sooner than expected, especially when turned on/off a lot. (They are not rated for how many on/off cycles they can tolerate only continuous on life.)
Also, the light quality of a good CFL (and any fluorescent) is also much better than the cheap CFLs. The bottom line is that you get what you pay for. HINT: write the date the CFL was purchased on the base of the CFL bulb. Then take it back to Walmart when it doesn’t last any where near the advertised “10,000 hours.”
BTW, you’ll often hear people saying not to turn florescent lights on and off because doing so wastes electricity. There really is no waste because the “waste” is in the in-rush which is simply charging up the capacitor where the energy is then used to power the light. Regardless, most of the in-rush is in the first half AC cycle, with less in the second half and less still in the third half cycle. By the end of the second full AC cycle the input capacitor is charged up and the input current has dropped to the operating current. Thus the extra power “waste” is only for 1/60 of a second or so and is negligible even after a few seconds when averaged out.
Are there toxic things in LEDs? Yes but they are in cased in nearly indestructible plastic (which is probably toxic too.) Anybody who says kids will get poisoned by eating LEDs like candy is either an environmental wacko or has some really dumb kids where evolutionary selection should come in to play. Besides, they eat dirt too which contains toxic materials. Should ban dirt too?
In any case, you can be sure that whatever toxic compounds are in LEDs there will be a lot more in cheap Chinese made LEDs. Probably in the plastic too. If they put toxic waste poison in dog and baby food you can bet they put it in LEDs too. FYI: I work for a company that has been manufacturing things in China for 30 years. We know the kind of sh** they do to save a penny.
Bottom line: good quality CFLs (from reliable, name brand MFRs) are a viable replacement and substitution for incandescent bulbs when you re looking to save money on electricity and bulbs. The mercury is really a non-issue. If they were really serious about it, they’d ban the bigger fluorescent bulbs. (And if they were really serious about AGW, they ban golf courses – more water vapor…). LEDs are really only viable for high maintenance lighting requirements (street lights etc) or if you really want to save electricity and don’t mind a 10-15 year pay back.
The anti-LED rant is patent nonsense. No child is going to lick a broken LED Christmas light because lead tastes sweet, even if one did somehow manage to crush one of these sturdy little buggers — a solid blob of clear plastic totally surrounding the LED element.
I use them to provide background lighting in the main cabin of my sailboat-home due to their low energy consumption — a couple of strings of ultra-bright white LED ‘pixie’ lights evenly lights up the whole cabin while we use directed reading lights for reading. Love ’em.
We are switching to LED ‘spotlights’ in our reading lamps as well, as they use 1/10th the electricity of incandescents, all 12 volts dc. Pricey, but so far we have not needed to replace any, and don’t expect to do so for years and years. They are rated up to 18 volts and we use them in the 12-13 volt range, extending the lives of their electronics .
I dont know about LED, for sure they do not wotk for human eyes as well as filament bulbs (I use a LED for seeing in small spaces to fit components but when it is tiny, and hard to see, I use a conventional flashlight and I can se better. CFLs are good in select use, somewhere where it is on in the morning and off last thing they are good, do the job and use less power, anywhere else they use more power and short life, you just cannot keep switching them on and off! as for envriomental issues they are a disaster, not that it is an issue but is there comparisom of “carbon” footprint for a CFL and a filament bulb? I suspect any power savings are eaten up with the hugely increased manufacture cost. Even the use of tin solder is suspect, it whiskeres and ruins the circuit, matbe we need indepenent investigation of all eco friendly ideas, I doubt many stand up, from the cat converters to wind power to light bulbs the green agenda has to lie its way in.
nemesis says:
I am curious to know what happens to used CFLs once disposed of. …Where do they finally end up?
I would guess that most of them end up in landfills.
Harry the Hacker says:
I have been using CFLs for over 15 years (they do save me money on my power bill, and did even when I was paying $10 each for them). I have taken to writing the installation date on the base of each lamp when it goes in, and have done this for 10 years now. My observations are that the lamp quality has decreased as they became mandatory and the prices went down (volumes shipped went up).
Amazing how simple economics works out – reduce competition, and you get a corresponding reduction in quality. Who’da thunk?
So in the interest of science; and also to save my bank balance, I went out and purchased a bunch of LED LAMPS last weekend.
I bought several of the phillips Brand 40 Watt Equivalent bulbs, that I mentioned before, whcih are specced at 450 Lumens and 8 Watts of electricity (more on this later). These were from Home Depot; haven’t found them elsewhere yet. HD aslo peddles an ECOSMART brand of bulbs, described as “assembled in the USA” and distributed by HD. I’ll find out who makes them.
I bought their version of the 40 Watt lamp and it is rated at 429 Lumnes and 9 Watts of juice, so slightly below the phillips numbers. The bulb looks as well built and rugged as the Phillips and it works virtually identically. I’m happy with either one, and they were the exact same price $21.97 each. So we now have six of the 40 watt bulbs, five of them Phillips.
Phillips also had a smaller spherical bulb 15 Watt equivalent, that uses 3W of electricity. I got one of thsoe for about $12 and that is now playing hide and seek in my refrigerator. Very nice lamp; and should last forever in the frig.
I also splurged ant spent $37 97 on the phillips “60 Watt” equivalent bulb. This has three striking hot orange dome segments, as part of the outer envelope; and it is those three pieces which light up bright white. Very nice lamp, and it currently is in a dimmable fixture. It consumes 12 Electrical Watts. I’m going to pull out the dimmer, so that I can then install the non-dimmable decorative tear dop Phillips bulbs that use about 2-3 Watts each. Tehy aren’t instant on, which is why they aren’t dimmable. There’s about a 1/2 second turn on delay; but that is less annoying than the ten minute warm up delay of CFLs.
Note that both white LEDs and CFLs generate some of their light from phosphors; all of it in the case of the CFLs, since the mercury discharge is producing UV radiation, which excites the phosphors. So both have bulb lifetimes that depend somewhat on degradation of the Phosphor. Same problem as CRTs and the like. This is NOT a big problem for ordinary fluorescents, and shouldn’t be with CFLs and less so for LEDs. The fluorescents of all types also get an ion bombardment of the phospher fromt he residual gas in the bulb; and this is the likely source of much of the phosphor degradation.. Not a big factor in my book.
But CFLs will always end up less efficient, since they start from a high photon energy UV and waste a good part of that getting down to the blue region which is the first really useful part of the spectrum. So the blue sourced LEDs of the cerium doped Yag type, are likely to be right up near the top of the efficiency chain.
Now I mentioned previously that 400 Lumens per Watt is a theoretical maximum. (for a source C white light). Note carefully that is the conversion from radiant EM emission is Watts, to Luminous equivalent in Lumens; so it is “Lumens per radiant Watt.”
For an incandescent lamp, which is basically a resistive heater, virtually 100% of the electric energy input is converted to thermal radiation; which is broad band, so the efficiency in Lumens (light) per Watt (electricity) is pretty much the same as the “efficacy” which is Lumens (light) per Watt (radiant Energy). So fromt he consumer point of view that is what matters; how mcuh light do I get from my electrical buck.
Now the peak of the “efficacy curve” otherwise known as the “Photopic Luminosity” curve is 680 Lumens per watt at 555 nm wavelength which is a green color. That is for a monochromatic light source; not a white leamp. The 4oo number is the highest you can achieve for a white lamp that matches Illuminant C, which is some sort of Standard.
Now the 100 Lumens per Watt, that I mentioned as alab result for white LEDS, is actually Lumens of white light per Watt of total radiant energy emission; so there’s a conversion form Watts of Electricity in the radiation out.
For single color LEDs, it is fairly simple; the best ones have essentially 100% internal Quantum efficiency; whcih means that every elctron or hole that crosses the junction results in the emission of a photon (internal to the crystal. Clever optical packaging has extracted as much as 58% or so of that light giving a 58% external quantum efficiency (the current record mightt be higher than that.
The emission energy for the more efficient typses on transparent substrates, is pretty much band gap emission; and the material bandgap is not too different from the diode forward Voltage. So you have Voltage times electrons per second, at the elctric end of things; and you have pretty much the same electron volts of Photon energy (2 eV photons are about 650 nm red) times the photons per second which is close to the electron rate; so as a rough estimate, the radiant energy Watts, is quite close to the Electric energy consumed. Now bear in mind that that is for the primary radiation from the LED semiconductor. By the time the Phosphors do their thing, there will be some additional losses.
The the lamps have to use a driver scircuit to control the drive current qaccording to some algorithm the manufacturer chooses; allowing for ambient Temperature and such.
It turns out theat the simplest way to drive an LED off the AC, is to pair them back to back (parallel) and then put a big capacitor in series with them. The current will be C dV/dt,s o you figure out the Voltage maximum slope rate, and find an AC capacitor type of the right number fo microfarads, and their is virtually no extraneous loss of power, as would occur in a resistive current limiter.
Well the Power company is not going to like you doing that to your whole house, because remeber that that current will be purely capacitative, so the power factor is going to go totally haywire. Maybe if you run the right number of electric motors and other inductive toys and gizmos, you can correct that. But for a string of 20 mA lamps to make a Merry Christmas sign, I don’t think that PG&E will have a fit if you capacitively drive that.
I did check out some other LED lamp brands; some of them made in the land of Rare Earths; but I didn’t buy any. Sylvania has some comparable lamsp also made offshore. Everybody charges that $22 for the 40Watt lamp.
You can find 6500 Kelvin white LED lamps, if you like looking like the living dead.
Teh 60 Watt Phillips is a humdinger; but a bit rich for my pocket book; so I’ll stay with the one for the moment. Not at all into spot lighjts;
And don’t waste your money on the clusters of 397 of 5 mm lamps; other than as toys for the kids; or for them to eat instead of candy; those things are so inefficient; besides being way overpriced.
The serious players are making some good products. I’m down to my last two CFLs to get rid of.
I should add; seeing that WUWT is an international watering hole; that I’m sure the big European lighting companies, like Osram, and Siemens, and I know there’s some other biggies whose names I just can’t recall right now; and of course Phillips is European; all are in the hunt with serious Products; that can only get better.
Now my family can leave the lights on and not have me chasing after them.
[George you write so much great stuff but please , please I am begging you , won’t you turn on your spell check?]
George E Smith said:
Are you saying that they are going to lose money?
I like that idea 🙂
“”””” [George you write so much great stuff but please , please I am begging you , won’t you turn on your spell check?] “””””
Izzat you Chasmod ? I didn’t know I had a spell checker ! I know Micro$oft WORD has a spell checker; but it only knows 1/10th of the words I use, so it gives all sorts of false spelling errors anyway. What good is that ?
I do try to re-scan everything I post to eliminate most of the dylsexic spelling flips, that my fingers make; but once in a while, they do slip by.
MODs have a free rein, open authorisation to make any spelling corrections they wish to on my junque; no questions asked.
But I will see what I can do to shape up.
George
“”””” Richard Sharpe says:
February 14, 2011 at 12:02 pm
George E Smith said:
Well the Power company is not going to like you doing that to your whole house, because remeber that that current will be purely capacitative, so the power factor is going to go totally haywire. Maybe if you run the right number of electric motors and other inductive toys and gizmos, you can correct that. But for a string of 20 mA lamps to make a Merry Christmas sign, I don’t think that PG&E will have a fit if you capacitively drive that.
Are you saying that they are going to lose money?
I like that idea 🙂 “””””
I don’t think that’s what is going to bother them. But they might get concerned about their wiring melting, due to poor power factor.
In any case LED lighting; unless you light up the whole of Times Square, is not going to have much impact on your total electric bill. (not on mine anyway.)