Electronic Design

CFLs For Illumination: The Hidden Catch

I have a bone to pick . . . with the idea of compact fluorescent lamps (CFLs) for illumination. CFLs have been in the news recently because a California legislator (Assemblyman Lloyd Levine, D-Van Nuys) wants to mandate "Dairy Queen" bulbs to replace incandescents. That same week, the Australian government announced plans to phase out incandescent light bulbs and replace them with more energy-efficient compact fluorescent bulbs across the country. The announcement by the Australian government reminded me of a story the Associated Press reported two years ago. Fidel Castro had launched a similar program, “sending youth brigades into homes and switching out regular bulbs for energy-saving ones to help battle electrical blackouts around the island…” The AP story went on to say that “The idea was later embraced by . . . Venezuelan President Hugo Chavez, who announced his own program to save energy and in recent months has given away millions of fluorescent bulbs in neighborhoods nationwide.”

Now, I’m a card-carrying bleeding-heart, green liberal. But the fact that politicians around the world are warming up to CFLs is just goofy, and the reason can be summed up in one word: mercury.

The news outlet that got it right was National Public Radio (NPR), although it took some listener thumping to get their attention. The original feature aired on “All Things Considered” (ATC) on Feb. 8, 2007, a puff piece about Wal-Mart’s push to sell 100 million compact fluorescent bulbs in 2007. The result, Wal-Mart said, would be grand savings on the part of consumers—to the tune of $3 billion over the life of the bulbs. There was a lot of happy talk after that.

The following Thursday, when ATC aired its segment with listener responses, there was a moment of clarity. NPR Environmental Editor Elizabeth Shogren responded on-air to a listener’s criticism with some hard facts. She had talked to John Skinner, executive director of the Solid Waste Association of North America, a national trade association for trash and recycling companies and dumps. Skinner noted that while it’s legal in most states for people to throw out compact bulbs, it’s not a good idea because the bulbs often break before they get to the landfill. As a result, trash collectors can be exposed to very high levels of mercury or the mercury could seep into the soil.

Shogren went on to look into recycling the bulbs. She discovered that even cities that have curbside recycling wouldn’t take the bulbs; they have to go to a hazardous waste collection bay. The closest center to Shogren’s home turned out to be 95 miles away. (One good source of this information is www.lamprecycle.org. They list 25 companies in the U.S. where you can drop off your CFLs, and 30 that have some kind of pickup service.)

Then Shogren talked to the Environmental Protection Agency (EPA). An EPA spokesperson said that the agency had been urging stores that sell the bulbs to help recycle them, but that so far the biggest sellers of the bulbs haven’t stepped up to the play. The one company that does recycle its CFLs is Ikea. (Wal-Mart was mentioned specifically; but they had not, at that time, responded to Shogren.)

So that’s where we are. CFLs are full of mercury; every box they are sold in says they must be recycled, but Shogren couldn’t find a single state or municipality in the United States that has a program for recycling CFLs. I guess that if you want to recycle, it’s best to buy your bulbs from IKEA, because you know they’ll take them back when they’re worn out. (Note: I have not actually tried recycling these bulbs at my local IKEA.)

What is the mercury doing in a CFL (or the cold-cathode fluorescent lamps—CCFLs—that we use in displays)? Well, it’s a mercury vapor arc that excites the phosphors on the inside of the tube. The mercury arc produces ultraviolet light at 254 nm, and that causes the phosphors to emit visible light. How much mercury is there? Generally, it’s 4 to 5 mg, but last year, Philips introduced a range of CFLs with mercury levels from 1.4 to 2 mg, depending on light output. The European Reduction of Harmful Substances (RoHS) standard for CFLs and CCFL backlights mandates no more than 5 mg.

But wait a minute. RoHS? No more than 5 mg?!? I’m hoarding the last of my eutectic Sn/Pb solder for my grandchildren’s electronic gadgets because they’ll never be able to buy solder with lead in it, and yet my laptop still has 5 mg of Hg in its backlight? That’s almost as goofy as politicians jumping on the CFL bandwagon.

Or maybe not. In the future, there wouldn’t be any laptops without CCFLs, so it’s not surprising there’s an exemption. How long the display-panel exemption lasts depends on how successful the people making diffusers for LED backlights are. I saw some big LED panels with nice, even backlighting at a conference last September, but I don’t know what it would take to bring those diffusers into mass production.What about LEDs, you ask? Those, of course, are made with gallium and indium, two poisonous metals (there is no free lunch), but RoHS does not yet address those toxins.

By the way, for electronic designers who are interested in driving either CCFL or LED display backlights, the Feb. 15, 2007 issue of Electronic Design has a good hands-on article on the subject by three engineers at Endicott Research Group (ERG). The quickest way to access it on-line is to enter the ED Online ID “14814” in the box at the top of the page at www.electronicdesign.com. In fact, that’s the best way to read the article, as it was too long fit into the print magazine. The ERG article covers all the design basics, especially with regards to CCFLs, which offer some interesting design challenges.

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