The Top 10 green living myths

5. Mercury emissions of CFLs versus incadescent lights: This is based on CFL mercury data from the EPA’s Energy Star Program. Mercury emissions per kWh are based on NERC subregion data from the EPA’s eGRID and state-level transmission loss data from the US Department of Energy. Health impacts of broken CFLs in homes based on remarks from Dr. Helen MacIntosh, a professor of environmental health at Harvard University, reported here.

6. Paper versus plastic: Paper and plastic bags both require comparable amounts of energy per bag for production, given that paper bags are considerably more massive than plastic ones, though paper bags are slightly preferred. Data on life-cycle carbon emissions for paper and plastic are taken from FRIDGE: Socio-economic impact assessment of the proposed plastic bag regulations. Other reports argue that paper bags have higher life-cycle GHG emissions, though methodologies and analysis boundaries differ across reports.

7. Electric cars: This is based on wheel-to-wheel efficiency data for Tesla Roadster and Toyota RAV4 electric vehicles and electricity generation emissions data from the EPA’s eGRID for each NERC subregion.

8. Planting trees to help alleviate global warming: There is a wide and contentious literature on this question, though most people agree that carbon benefits of afforestation in temperate areas is at least partially offset by albedo effects. One of the seminal papers on the subject is Bala et al (2007), where they argue that:

"...[in high latitude areas] the warming carbon-cycle effects of deforestation are overwhelmed by the net cooling associated with changes in albedo and evapotranspiration. Latitude-specific deforestation experiments indicate that afforestation projects in the tropics would be clearly beneficial in mitigating global-scale warming, but would be counterproductive if implemented at high latitudes and would offer only marginal benefits in temperate regions. Although these results question the efficacy of mid- and high-latitude afforestation projects for climate mitigation, forests remain environmentally valuable resources for many reasons unrelated to climate."

Click here for the paper.

9. Plastic milk jugs versus paper or glass: This is based on a the revised version of the comprehensive life-cycle analysis of plastic, paper, and glass half-gallon milk containers from Franklin Associates. You can find a summary of the report here.

10. Using the garbage disposal: Composting is ideal, but using the garbage disposal can be better from a carbon perspective than landfilling organic waste if your local wastewater treatment plant captures its methane emissions. This will differ by geographic area, and there are no good publicly available databases on which wastewater treatment plants capture methane and which do not. Note that there are cases in which waste disposed through the sink does not go to the sewer but is discharged to streams and rivers, and food waste can contribute to eutrophication and other nasty (though not carbon related) ecosystem impacts. See here and here for two contrasting views on this issue.

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