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CFL vs. incandescent: Battle of the bulb

Compact fluorescent lamps are more efficient than traditional light bulbs, but they also contain toxic mercury. MNN sheds light on which is the brighter pick.
By Russell McLendon
Tue, Jul 07 2009 at 4:00 AM EST
Read more: ENERGY EFFICIENCY, MERCURY, TOXINS & CHEMICALS

 
Compact fluorescent light bulbs are often mentioned as one of the easiest ways to shrink your power bill and your carbon footprint. They present the quintessential green-green situation: saving money and helping the environment. What's not to like?
 
There's the higher retail price — who wants to pay three bucks for a light bulb when it's sitting right next to ones that cost less than a dollar? But the CFL can last up to 10 times longer than incandescent bulbs, meaning you'd have to buy 10 of them during a single $3 CFL's lifespan. Each CFL saves about $30 during its tenure, according to the U.S. Energy Star program, and pays for itself in about six months.
 
One of the most potent threats to CFLs' superiority isn't their cost, but their contents. There's a small amount of toxic mercury in every one, which can be absorbed or inhaled, potentially causing brain damage in adults, children and especially in fetuses. Fumble a CFL while changing a light, critics warn, and you unleash a poisonous fiend in your home. Throw it out and you're dumping mercury in landfills.
 
Those are both valid concerns, if sometimes a bit overblown. You should be careful when cleaning up a broken CFL, but don't go nuts — Snopes has debunked the myth that breaking one requires calling in an environmental cleanup crew. Keep kids and pets away, open the windows and resist the urge to vacuum, since that can kick up mercury vapor into the air; see the EPA's advice on cleaning up broken fluorescent lights for a complete guide. When they do eventually burn out, make sure to dispose of them properly.
 

Why do CFLs contain mercury?

Fluorescent and incandescent lights generally work the same way: They zap certain types of atoms with energy until their electrons freak out and release photons of light. Incandescent bulbs do this by shooting electricity into a thin metal filament surrounded by inert gas and encased in a glass shell. Metal normally emits invisible infrared light when heated like this, but get the atoms worked up enough and they'll produce a visible glow, too.
 
Metallic atoms are also the light source in fluorescent lamps, but they use vaporized mercury instead of a solid filament. The incoming electrical current is carried through a glass tube, straight or coiled, that's filled with mercury vapor and argon gas. The electrified mercury atoms begin vibrating and releasing invisible ultraviolet light, which in turn excites a fluorescent phosphor coating on the inside of the tube, finally producing the visible light.
 
(It's this jittery relationship, combined with a jumpy magnetic ballast providing electricity, that gives fluorescent lights their infamous flicker. Electronic ballasts don't have this problem.)
 
Mercury is a crucial part of how all fluorescent bulbs work, and replacing it is a daunting task. Still, manufacturers have cut back on how much they use — CFLs' mercury content dropped by at least 20 percent from 2007 to 2008. While the bulbs contained an average of 4 milligrams a few years ago, many now use as little as 0.4 mg. By comparison, mercury thermometers contain about 500 mg of mercury, and older nondigital thermostats contain about 3,000 mg.
 

Does mercury overshadow CFLs' benefits?

Fluorescent lights only release mercury when their glass breaks. Consider how often you shatter a light bulb while changing it, and divide that number by 10 — since a single CFL requires about that many fewer replacements — and that's your risk of mercury exposure.
 
An incandescent bulb doesn't contain mercury, but it still has a higher overall mercury footprint than a CFL, thanks to the coiled tube's renowned energy efficiency. Coal-fired power plants are humans' No. 1 source of mercury pollution, and energy-intensive incandescent bulbs require those plants to burn more coal than CFLs do. That extra coal burning releases far more mercury than even the combined amount inside a CFL and in the coal emissions needed to light it.
 
While most fluorescent lamps finish their lives without shattering, however, it's another story once they're thrown out. They can easy break in trash cans, Dumpsters or en route to a landfill. It's only a small amount of mercury, but it adds up as more and more people are buying them, and it also endangers sanitation workers who don't know they're carrying bags containing mercury vapor. All the more reason to read up on the EPA's guidelines for properly disposing of fluorescent lights.
 

Are incandescent bulbs burned out?

The main downside with traditional light bulbs is that they use only 10 percent of their energy to produce light, burning off the rest as heat. They've wasted 90 percent of the electricity people have been feeding them for the past 130 years — electricity that was mainly generated from coal and other fossil fuels. Congress put its foot down with the 2007 energy bill, introducing tougher efficiency rules that are expected to crush the market for incandescent bulbs beginning in 2012. Within a few years, the ever-cheaper CFL may dominate the lighting market.
 
But don't count out Thomas Edison's original bright idea just yet. Despite the U.S. Department of Energy and EPA pushing CFLs, many people are still turned off by the light they emit, which is slightly bluer and more flickery than incandescents' warm, steady glow. To meet this lingering demand as well as the upcoming federal efficiency standards, several companies are scrambling to roll out a wave of next-generation incandescents. These bulbs keep their familiar shine and radiate less heat by reflecting some of the filament's light back inward. They're still more expensive than CFLs, but the price of such technology usually drops if it's successful.
 

Light(s) at the end of the tunnel

The future of artificial lighting is hazy, thanks to several recent technological and regulatory upheavals. Traditional light bulbs are almost certainly doomed once the new U.S. efficiency regulations take effect in 2012, leaving CFLs and improved incandescents to fill the void.
 
There's also a dark horse light bulb lurking in the shadows — light-emitting diodes, better-known as LEDs. These are already common in a variety of devices, ranging from the blinking red light on a video camera to the green power button on a computer. LEDs are more efficient, versatile and long-lasting than either incandescent or fluorescent lights, emitting light in a specific direction rather than radiating it outward indiscriminately, which wastes energy. They also absorb back what little heat they produce into an internal heat sink, leaving the LED itself cool to the touch.
 
While LEDs may seem like the obvious choice, they're still not entirely practical as a commercial substitute for incandescents or fluorescents. Several companies make bulbs that rely on diodes, but they aren't cheap. Odds are good the technology will eventually let LEDs overthrow their predecessors, but until then, the EPA and DOE are giving CFLs the green light.
 
For more on LEDs, CFLs and Hg, check out these 10 links from Uncle Sam:
 
MNN homepage photo: BlackJack3D/iStockphoto
Translating Uncle Sam homepage photo: Krista Kennell/ZUMA Press
All other photos courtesy EPA and DOE


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Comments(14)

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Posted By NOTPINKPRINCESS - Tue, Dec 08 2009 at 3:17 PM EST

I HOPE!!!!!

im hoping manufacturers can make new incandescent lightss! i dont want to put mercury in my home!!!

Posted By Anonymous - Tue, Dec 08 2009 at 3:46 PM EST

Bulb energy saver

Creative thinking and the most is bulb is consider as a energy saver . When we go to travel destinations use bulb as a energy consume.

Posted By Tex Lovera - Tue, Oct 13 2009 at 3:03 PM EST

And one more thing...

You also compare everyhting based on coal plants. As others have pointed out, the coal plant Hg emissions are being continually DECREASED, so that Hg will get reduced (and is not taken into account in the article's ana;lysis).

Plus, why do we still have coal-fired plants? BECAUSE THE GREENS WON'T LET US BUILD CLEAN NUCLEAR PLANTS. There's you're one-stop solution to a host of "green" concerns, but OMG it's a NUKE we can't have that!!!!

Posted By Tex Lovera - Tue, Oct 13 2009 at 2:58 PM EST

Lead-Shmead

The lead in incandescents is in the solder, which isn't AEROSOLIZED like the mercury in CFLs. You aren't going to get lead poisoning from a broken regular light bulb, but you'll inhale the mercury from a broken CFL.

The key line in this whole article is "Congress put its foot down...". Yeah, right on us. It's time for us to put the foot down on Congress. I don't need a nanny, you fatuous bunch of crooks. Don't tell me what toilet/showerhead/light bulb to buy. Convinceme on their.... More

Posted By green and proud - Thu, Oct 15 2009 at 5:36 PM EST

doing the right thing

People who blindly continue believing what they think is right in spite of all the facts clearly presented obviously could use a nanny. My major was in energy mgmt and I've studied these issues for 9 years now. At this point its simply ignorant to rant against a law the Pres. Bush signed when the "merits" are obvious to anyone with 2 or more brain cells to rub together. Like teabaggers, some people will advocate against their own best interest because of a lack of maturity and this attitude of.... More

Posted By Halogenica - Thu, Sep 24 2009 at 11:40 AM EST

Incandescent Light Bulbs do NOT Contain Lead

Old bulbs may still contain a dot of lead solder, but after 2006, leading manufacturers have ceased to use lead in light bulbs.

Posted By Aaron - Wed, Jul 08 2009 at 12:11 PM EST

Recycling bulbs isn't that hard...

If you have a lot of fluorescent bulbs in your facility you already know the cost and energy savings they can bring. Fortunately recycling them isn't all that hard or expensive. Using prepaid mail-in programs like EasyPak (http://www.lamprecycling.com) are pretty inexpensive and also guarantee that you won't get stuck with an EPA fine.

For more info see my blog at .... More

Posted By Halogenica - Thu, Sep 24 2009 at 12:00 PM EST

$34.95 for recycling??

Seriously Aaron, you're willing to pay another $34.95 to recycle your bulbs? Do you really think that after people have already payed a higher price for the CFLs initially, they're willing (and albe) to pay even more to get rid of them afterwards?

I rather suspect a lot of CFLs will end up in the trash...

Posted By Greg - Wed, Jan 13 2010 at 11:32 AM EST

re: "I rather suspect a lot of CFLs will end up in the trash...

Halogenica - I'm not sure where you live, but in our area every place that sells CFLs also accepts them back to recycle for free. There are containers at the front of the stores and you simply bring you lamps in a plastic bag and deposit them for free. Assuming lamps have burned out or broken, they're going to need replacing and for that you'll need a store. Anyone that can't be bothered to bring their old lamps in with them to the exact same place they're already heading is just plain.... More

Posted By peterdub - Tue, Jul 07 2009 at 4:59 PM EST

Why All Lights Have A Place in This World!

Thanks Russell for an interesting and balanced view of different lighting..

To put it in another perspective:
Americans choose to buy ordinary light bulbs around 9 times out of 10.
Banning what Americans want gives the supposed savings - no point in banning an impopular product!

If new LED lights -or improved incandescents- that you mention are good,
people will buy them - no need to ban ordinary light bulbs (little point).
If they are not good, people.... More

Posted By peterdub - Tue, Jul 07 2009 at 4:52 PM EST

Why CFL mercury is worse than Coal mercury!

RE Mercury : CFL v Coal Power
Why does this folk tale keep doing the rounds?
Greater coal power mercury problem was only ever true where untreated coal power dominated,
and is not true any longer.
New injection and photochemical techniques along with conventional gasification and wet scrubber use have -and will- dramatically reduce all coal power mercury emissions:
USA Government EPA: 90% reduction by 2018, (phase 1 = 21% reduction by 2010, phase 2 = 69% further.... More

Posted By Susan Barton - Tue, Jul 07 2009 at 2:07 PM EST

Light Bulbs' Dark Side

My sister-in-law's electrician told her about one of his clients who dropped and broke a CFL in her home. The package recommended that she call the EPA for disposal information. She called them and they had her seal that room closed with duct tape. They arrived in Haz-Mat suits 3 days later, removed the bulb and a circle of carpet and left her with a $5000 bill.

Posted By Cosmo - Wed, Jul 08 2009 at 12:56 PM EST

Re: The dark side

Sue,

There are three possible explanations for your comment

1) Either your sister in law or your sister in-laws electrician has lied to you, and made this story up.

2) You are repeating an old wives tale yourself, and your sister in law didn't even tell you this story, in which case you are promulgating false information (i.e lying), or

3) Someone at the EPA is in cahoots with hazmat teams, looking for suckers to pay 5K and pad their wallets.

I'm not even.... More

Posted By James Davies - Tue, Jul 07 2009 at 9:28 AM EST

Incandescent Light Bulbs Contain Lead

There is always a lot of talk about CFLs with their mercury and the associated dangers, which is valid and it is good to be careful. But incandescent light bulbs actually contain a significant amount of lead, which is also a potent neuro-toxin, so the mercury draw back of CFLs is not as significant as it might seem.

"Incandescent light bulbs contain lead at levels that exceed hazardous waste limits. " from: .... More

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