In article , Clot wrote:
Don Klipstein wrote:
I, Don Klipstein, need to correct my cost-per-1,000 hour figures for
CFLs, since I erred in a way unfavorable to CFLs.
It turns out I don't always do math well when my stomach is empty
and I smell dinner cooking.
I don't think I need to repeat these
Brilliant, (blast, didn't mean a pun), but to thank you for the correction.
An aspect that I have not seen any maths for is the amount of mercury that
has to be recovered/ disposed/lost through broken lamps compared to the
amount of mercury that would be emitted into the atmosphere through
combustion of coal for use of candescents.
Average CFL has 3.5-4 milligrams of mercury. If you take your dead ones
to Home Depot or any recycling dropoff point recommended by
www.lamprecycle.org, most of it gets recovered.
I saw one cite saying 24% of CFLs are properly disposed of. It is an
EPA document giving numbers that I consider a bit optimistic for amount of
mercury in CFLs and how much mercury emissions from coal they prevent:
http://www.epa.gov/waste/rcc/web-aca.../LindaBarr.pdf
That one does list other recycling resources.
Meanwhile, suppose as a less favorable example replaceing a 60 watt
incandescent with an 18 watt CFL that lasts 4500 hours. That saves 189
kilowatt-hours.
http://www.ecmag.com/index.cfm?fa=ar...rticleID=10261
cites an EPA figure of .012 milligram of mercury emitted into the
atmosphere by coal fired power plants per KWH of total USA electricity
usage. At this rate, that 189 KWH saved means 2.3 milligrams less mercury
pollution from coal-fired power plants - admittedly less than is in an
average CFL or even 76% of that (for 24% recycling rate), but not by a
whole lot.
Replacing 100 incandescents with CFLs should on average prevent emission
of more mercury than the CFLs contain, and with 75 watt ones it is on
average a close call. Replacing 60 watt incandescents should reduce net
mercury introduction to the environment if the recycling rate improves
from 24% or if national average life expectancy improves to 5300-6000
hours (likely soon).
- Don Klipstein )