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Re: [Phys-l] CFL's not such a hot idea



On 05/16/2007 04:00 PM, Crawford J Maccallum wrote:
We have to remember that the tradeoff is between 4 mg mercury in the landfill for a CFL vs a much larger amount put into the _air_ by a coal fired power plant providing the extra energy for an incandescent.

At least that's what I read.

Don't believe everything you read.

I checked the numbers. According to the EPA web site, the US
puts a couple hundred tons of mercury compounds into the air
annually. Of that "only" 50 tons is attributed to the electrical
power industry. If you pro-rate that over the total electrical
power on the order of 100 quads per year (not exactly right,
but close) that comes to something like 5e-13 grams of Hg
per watt of electricity. If you run a 100-watt incandescent
for 2000 hours, you can only impute a fraction of a mg of
Hg to that energy, so even if the CFL saved 100% of that
energy it would still be on the wrong side of the tradeoff.

Y'all are welcome to double-check my estimates.

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With or without CFLs, 50 tons (or more) of mercury in the air
is pretty scary.