Using compact fluorescent lighting can sharply reduce energy use. However, the small amount of mercury in each CFL has raised concerns, due to the threat of mercury exposure via broken bulbs or through the disposal process.
Now a team of Yale scientists has estimated, on a state and national basis, the tradeoffs between reductions in mercury from coal-fired power plants, due to less energy use, and increased use of mercury-containing CFLs. They have concluded that eight states will end up with more local emissions of mercury — AK, CA, ID, ME, NH, OR, RI, and VT. At the opposite end of the spectrum, ND, NM, and WV will have the greatest net reduction in local mercury emissions. The other 39 states will have smaller net reductions.
Among the 130 countries evaluated, those with the biggest net reductions include Estonia, Romania, Bulgaria, and Greece. China will have the greatest total reduction. The US will have a modest net reduction in emissions, and Canada and Mexico will see slight net reductions. Areas in Central and South America, Africa, the Middle East, and Europe will see the biggest increases.
The team's calculations are based on factors such as a region's dependence on coal-fired energy, the coal's chemical makeup, thermal conversion efficiencies, distribution losses, emissions during CFL manufacture, and existing CFL recycling programs. There are limitations in the data that create some uncertainty in the final numbers, and some of the calculations will change if mercury content in CFLs decreases, recycling rates increase, or power plant emissions are reduced.
Despite these weaknesses in their approach, the authors say their findings suggest that any mandates for the use of CFLs might best be made at the local level. An alternative might be to move forward with national mandates, provided they include assessment, acknowledgment, and resolution of local impacts.
- "Spatial Assessment of Net Mercury Emissions from the Use of Fluorescent Bulbs," Eckelman et al., Environmental Science & Technology, online Oct. 1, 2008 (abstract ); for a copy of the full study, contact co-author Julie Zimmerman,  203-432-9703 (email preferred); Oct. 1, 2008, press release. 
For much more on CFLs and mercury, see the TipSheet of June 6, 2007.