The Chemistry Of Light Bulbs—And Why CFL’s Are Overrated

Science 2.0 ^ | Mar 26 2011 | Enrico Uva

[neverdem]

Light bulbs rely not only on simple materials but on esoteric ions and compounds. And while we take their emissions, visible light, for granted, the inner workings of these deceivingly simple gadgets depend on the complex behavior of electrons.

We’ll discuss four types of light bulbs:incandescent bulbs, halogens, fluorescent lights (including CFL’s) and LED’s.

A) INCANDESCENT BULBS

The light bulb of the short-lived variety, is the traditional tungsten incandescent bulb. Inside the glass, electricity flows through a thin filament of the element tungsten (chemical symbol, W, for its old name wolfram).

Because the wire is so thin, resistance is high, and it raises the temperature of the tungsten wire, so chosen because of its high melting point of 3410 oC. At the bulb’s temperature, which is about 1000o cooler, excited electrons that return to lower energy states release photons of a frequency that is visible to the human eye. The radiation is intense in the red to yellow regions but compared to daylight, the

spectrum of an incandescent light bulb is very weak in the 400 to 500 nm region (blue). This would be nice to verify with a prism, and is the reason that plants don’t do as well if grown under such light. Although the heat is not sufficient to melt the tungsten it would certainly fry the heck out of it in an oxidizing atmosphere. Thus manufacturers replace oxygen with a mixture of the less reactive nitrogen and the noble gas argon. Note that a vacuum would not be a good solution because the tungsten would vaporize even more easily and dramatically shorten the bulb’s lifespan.

Even within an argon-nitrogen atmosphere, however, the heat causes some of the tungsten to sublimate. Some of it returns to the wire as it bounces off the argon gas, but a good deal ends up on the glass. This is one of the reasons incandescent bulbs tend to get darker with increased use. The glass suffers more abuse from plain old electrons which fly off the filament as if it were a cathode ray tube from a conventional television set. Such electrons cause tiny black spots to appear. These first caught Edison’s attention, but he had never time for further investigations; otherwise, as David Bodanis suggests, Edison may have discovered electrons before J.J. Thomson. To create a more diffuse light but perhaps in an attempt to camouflage all the future damage, manufacturers treat light bulb glass with hydrofluoric acid one of the few acids that can attack glass) which creates that familiar frosty look.

B)HALOGENS

Eventually the tungsten wire becomes so thin, that it snaps, breaking the circuit and sending you off to the hardware store. At one point someone got tired of the bulb’s short lifespan and invented the halogen light bulb. This still uses tungsten but along with argon it includes a small amount a halogen gas, namely chlorine. The reactive gas combines with the tungsten vapour and deposits it again on the filament. In other words it recycles the tungsten, rather than letting it wastefully deposit on the glass. Of course, it is very unlikely that the metal will be perfectly and evenly replaced all along the coiled filament. Weak spots eventually develop, and the coil still breaks, but it takes a lot longer, and halogen bulbs outlive their incandescent counterparts. The glass has to be able to withstand higher temperatures, so they use a purer form of silicon dioxide, one that unfortunately gets ruined by oils on our skin. If these bulbs are mishandled as such, the grease should be washed away with alcohol.

C)FLUORESCENT BULBS

To avoid wasting energy in the form of heat, fluorescent lights, ubiquitous in schools and other institutions, operate by a totally different principle. They contain a small amount of mercury(Hg), which emits ultraviolet light when excited by electrical energy. The story cannot end there because ultraviolet(UV) is invisible to the human eye. The walls of the bulbs are coated with a phosphor, usually a halophosphate such as Ca5(PO4)3(F,Cl) with ions of Sb3+ and Mn2+ that absorb the UV radiation. The excited electrons then release visible light, compliments of fluorescence. In this form of luminescence, an excited electron returns from a specific molecular orbital to a lower one without inverting its spin. The resulting light has the bulk of its intense wavelengths in the yellow and blue regions. But relative to natural light, fluorescence is weak in the red regions. Plants will again remain "unhappy", unless you buy more expensive fluorescent lights which try to compensate for this weakness by substituting antimony and manganese ions in the phosphor with europium and terbium ions.

Next we come to the smaller version of type 3 bulbs, compact fluorescent bulbs(CFL's), which are overrated for three reasons:

(1) Practically, the CFL’s are not as bright as halogens and although they match the light intensity of incandescent bulbs, they take a while to reach their peak intensity.

(2) They were not designed for cold climates, where the traditional bulb’s inefficiency is less of a drawback. The heat generation is actually desirable for about 9 months of the year in the northern states and Canada because it means the main heat source in the home does not have to work as hard.

(3) It’s ironic that something marketed as an environmental savior actually contains mercury. According to Environment Canada, the Hg content varies from 1 to 25 mg per bulb. There are about 115 million American households. If each household breaks 3 bulbs per year either by accident or indirectly by sending them to a landfill, then between 300 kg and 9000 kg of mercury (one significant figure) are added to the environment in the United States alone. The annual mercury emissions from all sources in the United States are estimated at 43 700 kg ( over 12000 kg from Alaska).

D)LEDS

To gain insight into how an LED (light emitting diode) bulb works we need to be reminded that a diode consists of two adjacent wafers of silicon doped with different impurities. The latter do not have the same valence number as silicon. If the impurity or "doping agent" is short of an electron(for example, boron), its wafer will receive an electron from the wafer with the opposite problem(example arsenic). Since electrons are stepping down from a higher energy level, photons are released. The energy gap is usually small and will only emit in the infrared, but it’s still useful if you want to use the remote control to turn off your daughter’s music channel.

To get visible light you need to get away from the classic boron-arsenic combo representing a valence of 3 and 5, respectively. If aluminum and gallium(each with a valence of 3) replace boron, one can create a red LED. If indium replaces aluminum, the transition energy increases, and blue light is released. The third primary color is created by replacing arsenic with another valence 5 element, phosphorus, and combining it with aluminum and gallium. A white color can result from combining all three recipes or by coating the bulb with a phosphor.

Although there are still technical challenges ahead, LED lights will probably replace CFC's. But perhaps not to add too much arsenic to the environment, we should also use incandescent light or simply wait for sunrise to read science.

References

University Corporation for Atmospheric Research http://www.ucar.edu/news/releases/2007/nicc-table.shtml

US Census http://www.census.gov/prod/1/pop/p25-1129.pdf

Environment Canada http://www.ec.gc.ca/mercure-mercury/default.asp?lang=En&n=2486B388-1

Efficiency of CFL’s http://www.cbc.ca/news/canada/manitoba/story/2009/03/04/mb-light-bulbs.html

US Department of Energy http://www1.eere.energy.gov/buildings/ssl/how.html

http://science.howstuffworks.com/light-bulb2.htm

Bodanis, David. Electric Universe. Crown. 2005

Britannica. DVD edition. 2000

Haber Schaim and Al. PSSC Physics. Heath. 1971

[ADemocratNoMore]

> the scam artists that live off the government will suddenly start up all these “Toxic metal removal” companies

They are doing that right now!. A few years ago, somebody broke a thermometer in a street in a residential neighborhood. The street was shut down for a couple of days while two or three guys in moon suits cleaned it up. Just a hunch, but I think it highly probable the moon suit guys were getting paid minimum wage and the city was getting charged plenty (100$/hr, more?).

[Publius6961]

All I can report is that I have used CFLs since they were $5-$6 each, in all the fixtures that could tolerate them,

Whatever has been said pro or con, I can report that none, not any have lasted even remotely close to the "up to 10,000 hours" useful life of sevice.

More like between 500 and 1000; about the same as most incandescents at about 50% bigger price or more.

[Publius6961]

Yup. Just look up how to handle CFLs on the EPA website. Lol.

I would get a dozen life sentences back to back if they ever found out how I deal with them, LOL.

[Ronin]

It’s a pretty good bet. For years, my better half has been complaining about the bedside lamp I use to read while she sleeps. I recently purchased a nifty little LED lamp that puts out some amazingly focused light in a circle just big enough for me to read comfortably. Bright sucker too! I can actually work under that light if I need to.

I am also seriously considering upgrading my four-cell Maglite with a three-LED conversion kit that will allow me to output 700 lumens. Any bad guy hit in the face with that much light is not going to be doing anything but rolling on the ground and screaming.

Hey, this is Japan, no guns...

[Wonder Warthog]

Sure. But there are ways to lessen the problems of perceived color. They won't be a perfect match, but perhaps enough to solve "mimaw"'s problem. I read a LOT, all of it by CFL light. No problems. But I "did" take the time to order CFL's with a spectral range more similar to incandescents that what is normally found in the local hardware store.

Fortunately, I'm not bothered by the 60 Hz "flicker". For THAT, there is no cure other than not using CFL's (or regular tube fluorescents, for that matter).

[rlmorel]

I grew up as a military brat, and anybody who’s done so will tell you (at least I suppose, the boys will) that one of the interesting and fun things about that is on nearly every military base, there are usually scores of closed up buildings that are no longer in use. Most of these buildings can’t be entered, but there’s always some that have some way in through a window, or a door with a faulty lock and so on.

Once inside, it’s always interesting… there’s desks but still have stuff in the drawers, odd electrical contraptions that are nonfunctioning and have mysterious purposes. There were always containers of “stuff” that could’ve been anything.

I remember going into an old rickety building one time with a buddy, and they all these pipes going in every direction that were covered with asbestos. We would break off huge pieces, 6 foot long half shells tore away from the pipes… we would raise them over the tops of our heads, rush towards the wall and throw them against it. They would explode in a huge cloud of white engulfing dust. We would be covered from head to toe in this asbestos dust… I remember going home and walking in the house like that one time, and my mother looked at me in bewildered bafflement as she yelled at me in exasperation “What the hell have you been doing?!”

My brother came home one day with a bottle of Mercury. Not like a little tiny vial of Mercury, but an entire bottle, I would guess about 6 fluid ounces. We would pour it onto the floor and make a huge Mercury puddle, dividing it up into smaller bottles with our hands while holding it in our hands as we ported back and forth between our palms…

It’s hard to believe, but there it is. I think I was between 10 and 13 years old when I was doing this kind of stuff, I had no idea. I guess it wasn’t really important to think that this stuff might be dangerous, the asbestos and the Mercury. I have had borderline high blood pressure ever since I joined the Navy, and my liver function tests have always been elevated, so I guess it will probably catch up to me one of these days.

All in all, I’ve always suspected that I probably did worse off by being born prematurely right around seven months (at 2 lbs. 11 oz.), but I suppose I’m just rationalizing my youthful idiocy… :-)

The point is, I’ve always suspected that your heredity is a lot more dangerous than many of the environmental things or crises of the day that are hyped by liberals. You know what I mean, one day they say coffee is good for you, next day they say it’s bad. One day they tell you that fat is bad for you, the next day they tell you that cutting out too much of it can be harmful, and so on.

I don’t watch television any more, don’t read newspapers and don’t read magazines like Newsweek, Time or U.S. News & World Report. I know a lot of people who get completely crazed as they watch or read this stuff, and every day there is something new that’s going to kill you. I just saw something recently that had the title “Is kissing your pet bad for you?”

I figure I’ve got enough crap in life to worry about, and touching a doorknob or giving a dog a smooch on the top of the head probably pales in comparison to the possibility of being squished by a Mack truck on my way to work.

[rlmorel]

I agree, I’ve had the same experience. This is all BS, it’s a scam. I agree with some of the posters that if you get the right type of light, they are kind of okay, and don’t give off that unnatural and unpleasant greenish or bluish tinge.

What I detest about the fricking things is that if you turn them on, sometimes it takes a while for them to reach a stage where they give off all like they should. That irritates me, especially when I go out in my garage and switch on the light and fumble around for a while until the thing actually gets warmed up.

This is all just another reason I detest and hate liberalism and nanny statism.

[stranger and pilgrim]

CFL not bright enough? Go up one wattage (use a 15-watt CFL instead of a 13)
Don’t like the color? Try a different color.
Had one that didn’t last as long as promised? You should have saved your receipt and taken it back for a replacement.
None of the CFL’s you buy last? Quit buying cheap, off-brand bulbs.
CFL’s too expensive? Are you kidding? According to the U.S. Department of Energy, each CFL saves the consumer $35 over the life of the bulb compared to using (and replacing) incandescent bulbs. Remember, 90 percent of the energy consumed by incandescents is wasted as heat, not light.
But I live in a cold climate, heat is good, right? Surely there are more economical ways of heating your home than running light bulbs?
Sticker shock still got you down? Look for sales. Better yet, watch for rebates from your utility company. Some electric companies will even give you some bulbs.
CFLs won’t fit your fixture? Shop around. There is probably one that will (they’ve gotten smaller, you know). Or, worst case, don’t use a CFL in THAT fixture.
CFL’s don’t work in ceiling fans? Sure they do. You just have to buy the right ones.
CFL’s don’t work in the cold? OK, use an incandescent bulb in your outdoor fixture. You have permission.
But they contain mercury! Please, you probably work in an office or store with the entire ceiling lined with traditional fluorescent light bulbs. You’ve been existing underneath a sea of mercury for 40 years and you’re now just starting to care? Give us a break. Hell, if we were talking about mercury in fish, you’d be telling us about how you used to play with the mercury from broken thermometers and it never hurt you . . .
LEDs will be better: OK, great. When they become widely available at an economical price, use them.

OK? Does that about cover it? I have never seen a case where so-called “conservatives” were so committed to wasting money. It’s just hard-headedness. CFL’s are a great improvement over 140-year-old technology. Yeah, they look funny. Yeah, they’re different. Get over it. They’re better and they will save you money. Besides, if we don’t start saving energy soon, you’re going to be faced with a lot worse choices in your life than whether to use curly bulbs.

[rlmorel]

Get over yourself you rightous piece of liberal statist crap. What the hell are you doing on this forum, siding with government intrusion into our lives?

If I want to waste money, it is my OWN damned business.

If the market wanted these turd lightbulbs, they would have made it on their own without government legislation.

It is morons like YOU who are responsible for this statist mess we are in covering everything from legislation against transfats and salt in the diet to the amount of water we can flush down our toilet.

Idiot. You think this is great because it is your pet thing, you have bought hook, line and sinker into the liberals running around screaming that we are running out of energy. I’ll bet you buy into the global warming crap too. It is people like YOU who invite our government to intrude into EVERY facet of our life.

Ok? Does THAT cover it?

[rlmorel]

And by the way, my issue does NOT have anything to do with mercury. Did you see me say it did? No, you didn’t, because I didn’t say it any YOU can’t read.

My issue is that I have to spend far more for a product that lasts far less and doesn’t last any longer, all because some statist jerkoff like you TELLS me I have to.

And I am damned sick of busybodies like you. So if you want to be a snide, limp wristed statist, go somewhere else and do it. We aren’t buying your crap here.

OK? Does THAT about cover it?

[mongo141]

Get over yourself you rightous piece of liberal statist crap. What the hell are you doing on this forum, siding with government intrusion into our lives?

If I want to waste money, it is my OWN damned business.

If the market wanted these turd lightbulbs, they would have made it on their own without government legislation.

It is morons like YOU who are responsible for this statist mess we are in covering everything from legislation against transfats and salt in the diet to the amount of water we can flush down our toilet.

Idiot. You think this is great because it is your pet thing, you have bought hook, line and sinker into the liberals running around screaming that we are running out of energy. I’ll bet you buy into the global warming crap too. It is people like YOU who invite our government to intrude into EVERY facet of our life.

Ok? Does THAT cover it?

Excellent!!! You are exactly right.

[rlmorel]

Normally I try not to get that worked up, especially over darned light bulbs. In this case (apart from the snide condescension) is is clearly the principle that irks me.

It is this caving into liberalism, allowing their premises to go unchallenged that is leading us down the road to ruin.

There have been tens of millions of deaths worldwide due to malaria and other insect-borne diseases since DDT was banned in the early Seventies, and DDT was banned on faulty premises with no evaluation of the risk/benefit aspect in much the same way incandescent lightbulbs were banned.

It is the same principle. Someone made the decision it was bad for us to have them based on global warming/peak energy/(INSERT YOUR FAVORITE LIBERAL REASON HERE) and is going to make them unavailable to Americans.

Yesterday it was DDT. Today it is lightbulbs. Tomorrow it may be trans-fats or salt, and the day after that it could well be cars/guns/whathaveyou.

I will apologize to the poster for my incivility, but the principle stands.

[rlmorel]

I apologize for my incivility in this discussion.

You hit a nerve on me that is lying raw and open right now, and did not deserve that level of vituperation.

You could have made your point differently and perhaps it might not have hit me the same way, but that does not in any way excuse me for stooping to that level.

I try not to have discourse with people online that I would not have to their face, and I do not think if we were face to face I would have resorted to that level of abrasiveness, and thus it fails my test.

[stranger and pilgrim]

No need to worry. I took no offense. Clearly, your response was one of a madman, if only temporarily so . . .

For the record:
1.) I am not a liberal. Not in any way, shape or form.
2.) I am not a statist. NOt in any way, shape or form.
3.) I do not support government mandates about light bulbs. Not in any way, shape or form.

What I am is someone who worked in the electric utility industry for 20+ years as a writer and communicator. A big part of my job involved spreading the company line. That, as much as anything made me a believer in energy efficiency.

We are facing an impending power shortage in America. Our appetite for electricity continues to grow. Think about how many things you plug in today compared to 20 years ago. And yet, in the past 20 years we have built almost no central station baseload power generating stations. Our existing backbone of powerplants is getting old. The cost to update them to current EPA regulations is insurmountable in many cases — assuming the Sierra Club and EPA would let the power companies upgrade old plants. We can’t build any new coal plants — no banks will loan the money for fear that EPA will decide no more coal. It looked like nuclear might once again have a chance, but Japan pretty well killed that. Wind and solar are a joke. Basically, we’re screwed.

Eventually, we’re going to have to come up with a solution. In the meantime, we have to make do with what we have. We have to stretch every kilowatt as far as possible. That means we can’t waste energy. Incandescent light bulbs waste 90 percent of the energy they consume. Changing to CFLs is a no-brainer. It’s low-hanging fruit. Easily done, almost no pain and doing so produces very real, tangible savings for the consumer. I’m sorry if you find this offensive but I believe anyone who continues to buy and use incandescents where they don’t HAVE to is a damn fool. Idiot would not be too strong a word. It really is that simple. Government mandates have nothing to do with it. It’s just plain economics.

And, believe me, this is the LEAST of the choices you will be facing in coming years. What are you going to say when they tell you have to replace your refrigerator?

I no longer work in the electric utility industry but I learned enough to know that CFLs are a great money and energy saver and those who oppose them are just being stupid. Sorry. But that’s the truth.

[aruanan]

Government mandates have nothing to do with it. It’s just plain economics.

If it were just plain economics, there would be no necessity of any government mandates. And the savings realized are in the ideal use of the CFL compared to average use of incandescent. And, sorry, there are no CFLs available that can give me the type and brilliance of lighting that incandescent (including halogen) can. That is as important a factor as "energy use." If it's doing what I need it to do in a way that another thing cannot, then the energy simply is not wasted--it's just part of the cost.

[stranger and pilgrim]

Again, I don’t support the mandate, nor do I think it was necessary. The facts are enough to convince most people.

Also, to repeat myself, I don’t think people realize how dire the energy situation in America is going to be in a few years. I predict you will look back at the controversy over these light bulbs as quaint.

Utility companies are scrambling to figure out how to keep the lights on. Just a few things I have heard discussed:
— incentive/rebate programs for replacing refrigerators (abandoned for fears about freon/CFCs)
— incentives/rebates for home weatherization, insulation, etc.
— time of day metering with higher rates during peak hours
— voluntary load management programs where utilities would offer attractive rates to consumers who allowed the utility to cycle high demand appliances and HVAC systems off during peak times
— mandatory load management programs
— SIGNIFICANT rate hikes on a more or less annual basis, with no end in sight.

Waste energy all you want. But you WILL pay for your stubbornness. But tell me something. When, exactly, did WASTE become a conservative ideal?

[rlmorel]

Thank you.

You said "...doing so produces very real, tangible savings for the consumer. I’m sorry if you find this offensive..."

That isn't what I find offensive. What I find offensive is your tone in relaying your opinion. I am not going to quibble with someone over whether they save money, whether they are better or worse for the environment or whatever. People are entitled to their opinion.

So, I do take issue with is your tone, but what I take issue with even more so, is with government bureaucrats taking my money via confiscatory taxes, TELLING me how to spend the money they leave me, then passing legislation to DRIVE up the cost of energy so we are FORCED to spend more money to drive our cars, heat our homes and turn on our lights, whether they be incandescent or CFL. These bastards think they are doing us a big favor because they think they know best, and are trying to twist our arms to accept their utopian crap. They think if energy costs go up high enough, their plans to harness unicorn flatulence or whatever will become economically viable.

Well I don't care to take part in their damned experiments. If my town wants to purchase LED based traffic and street lights because it saves the town money and is a guaranteed return on investment, then power to them.

If you and others with your point of view want these CFL lights in the marketplace as an alternative to make your home more energy efficient, then I think is is fine and would never say boo to anyone so inclined.

Our issue is not residential lighting. Making citizens like you and me purchase stuff we don't want and don't need is NOT going to solve anything. It is the equivalent of selling carbon credits or putting a magnetic sticker on the back of a car. It is Jimmy Carter wearing sweaters and telling us to turn our thermostats down.

I just took this well known (I presume) graph from Livermore Labs showing energy sources and consumption and cut out a part of it and marked it up. Of the four major sectors, residential is the smallest using just 4.65% of generated electrical power as shown by the graph. Government statistics say lighting consumes 12% of 4.65% of electricity flowing into a house.

On this graph below, the blown up part shows the 4.65% pipeline with the red stripe on it showing the lighting share, and the green stripe showing what it would be if we assume 10% efficiency compared to CFL for incandescent bulbs.

I didn't get this image from some anti-enviroweenie website. I made it myself after analyzing the data on the graph and government data such as estimates of how much lighting uses.

I didn't disparage you for choosing CFL's as a stand to take. You disparaged me with sarcasm for taking the stand I took, which I took exception to. I believe I have the data (shown graphically here) to indicate that using CFL's in houses isn't going to save us. You can make an argument for commercial/industrial building codes and so on, and I might buy into it and agree, the same as I agree with towns purchasing led-based traffic lights.

By my home is my home. And we have gone far too long allowing the government to dictate what we can and cannot do on our own quarter acre of land, small as it is. I am sick to death of it.

[rlmorel]

Correction. The residential sector is the SECOND smallest.

[rlmorel]

Excellent and fascinating post...thanks!

[stranger and pilgrim]

My tone?

Really?

Grow up.