Just a Bulb?
Just a Bulb?
By John Atkeison
How can a little compact fluorescent lamp be controversial? It’s just a light bulb, right?
There are a few issues that are important, some more than others, and some that have come up only now that compact fluorescents are very common. Many of these are relevant to tubular fluorescents as well.
These bulbs use a lot less electricity to produce light. While the old incandescent bulbs produce heat with three quarters of their electricity, compact fluorescents (CFLs) use that proportion to produce light. So using CFLs can result in a dramatic lowering of the part of your electric bill that is used for lighting just as using tubular lighting does. This gives them a competitive advantage for business and residential customers.
The main controversy that has come up with CFLs is the small amount of the element mercury that is used in them. The mercury is necessary for fluorescents: electricity energizes the mercury, which responds by emitting ultraviolet light, which then energizes the phosphor material that coats the inside of the bulb, which respond by producing the light that we use.
The bad news is that mercury can be a terrible neurotoxin. It is already present in measurable levels in the bodies of almost all American women of child bearing age, and this poses a real threat to the neural development of children as they develop in their mother’s womb.
The good news comes in two parts. First, the mercury in CFLs is between one and five milligrams—just about the size of the period at the end of this sentence. In the rare case where a bulb is broken it makes sense to clean it up carefully, but the scare stories about treating them as toxic waste have turned out to be pretty overblown. (Here’s what you do: don’t let the kids play in the broken bulb, gently sweep the broken bulb into a bag and seal it, pick up the residue with sticky tape, double-bag it all and dispose of it in the trash carefully.)
The second part of the good news is that using CFLs can account for a big reduction in overall mercury pollution in the environment if the electricity they use is generated in coal-fired power plants. It turns out that mercury just naturally occurs in coal, and when we burn the coal, the mercury goes right up the smokestack, and right back down to us. (In Nebraska, we get 70% of our electricity by burning coal in generating plants.) The old incandescent bulbs are responsible for around four times as much mercury pollution, simply because they waste so much power.
Enter WasteCap Nebraska’s Another Bright Idea (ABI) CFL recycling program. http://www.wastecapne.org/anotherbrightidea/
As you can see from the chart above, recycling can take care of a big portion—about a third– of the mercury. ABI has coordinated local retailers and libraries to take CFLs and recycle them at no charge. Check the web site to find one near you, and be part of the Thousand Bulb Challenge.
Just turn it off! Or not…
Now that fluorescent lights are everywhere another question comes up: how often should we turn them on and off?
Opinions abound! One thing that seems clear is that frequent switching on and off shortens the life of the bulb. It is hard to be precise about just how much because the equipment itself varies so much, but for tubular bulbs, estimates can be made. Some manufacturers’ reference time for tubes to burn continuously is three hours, and extending that time to 12 or more hours—rather than switching it several times– can double the life of the bulb. That is a pretty big difference.
If we are measuring the total “energy footprint” of a bulb or fixture, it just makes sense to estimate the whole life-cycle energy costs as much as possible.
While everyone agrees that there is a larger burst of energy that is required to start up both tubular and CFL bulbs, there is no reliable way to predict just how much. The problem is that there are different kinds of start-up devices (ballasts) and vastly different levels of quality between brands of bulbs.
Here’s what I am going to do, personally. First, I’m going to try to estimate all the costs of the bulbs, especially with regard to the greenhouse gas emissions, since I think climate changes caused by global warming are the biggest problem facing me and my grandkids. Greenhouse pollution is sort of easy to figure in, since burning coal is the biggest villain in that story, and we’ve already seen how it fits in as a source of mercury. Cost and efficiency count a lot also. And I am not going to wait for the next big thing, which is likely to be LEDs. While that matures, I can be saving money, mercury, energy, and greenhouse gas pollution.
It is simple, really: I’ll use fluorescents. I won’t flick them on and off. With tubes, I’ll leave them on for a whole shift of work or while I cook the entire holiday meal. For the CFLs, I’ll start to watch my habits and patterns, and if I am likely to be back in a storage room or bedroom lit with CFLs in 15 minutes, I’ll probably leave that on, too.
Happy Holidays!
References: The graphic comes from the EPA: Mercury_emissions_by_light_source_EPA_2008.svg
Google it, and you will see the variety of opinion about the switching issue.
For an example of prolonging tube life, see page 4 in http://www.lrc.rpi.edu/programs/NLPIP/lightinganswers/pdf/view/LAT8.pdf