Last week’s publication of an article in Environmental Science & Technology (ES&T) by Stanford University professor Mark Jacobson, in which he projects that fleet-wide use of E85 in the United States could increase the number of respiratory-related deaths and hospitalizations (earlier post), has stimulated counter arguments from several groups, including various state American Lung Association organizations, the Natural Resources Defense Council (NRDC) and the American Coalition for Ethanol.
In his paper, Jacobson concluded in the abstract that “Due to its ozone effects, future E85 may be a greater overall public health risk than gasoline. However, because of the uncertainty in future emission regulations, it can be concluded with confidence only that E85 is unlikely to improve air quality over future gasoline vehicles. Unburned ethanol emissions from E85 may result in a global-scale source of acetaldehyde larger than that of direct emissions.”
In remarks outside the paper, Jacobson was somewhat more aggressive in characterizing the results of the study.
Today, there is a lot of investment in ethanol, but we found that using E85 will cause at least as much health damage as gasoline, which already causes about 10,000 U.S. premature deaths annually from ozone and particulate matter. The question is, if we’re not getting any health benefits, then why continue to promote ethanol and other biofuels?
There are alternatives, such as battery-electric, plug-in-hybrid and hydrogen-fuel cell vehicles, whose energy can be derived from wind or solar power. These vehicles produce virtually no toxic emissions or greenhouse gases and cause very little disruption to the land—unlike ethanol made from corn or switchgrass, which will require millions of acres of farmland to mass-produce. It would seem prudent, therefore, to address climate, health and energy with technologies that have known benefits.
The American Lung Association of the Upper Midwest—a strong supporter of the use of E85—countered first by focusing on the assumption in the study that all vehicles will be operating on E85 in 2020.
E85 was never intended as a complete gasoline replacement, and will only be capable of achieving a portion of the total US fuel demand. Additionally, the areas of the county where this study demonstrates E85 to have the most harmful effects are where E85 is not currently manufactured or sold, making them the least likely areas of concern.
Additionally, the ALA noted that while ethanol-based fuels may increase the emissions of aldehydes, it reduces two air pollutants linked to cancer, benzene and butadiene. (Both those results of the use of ethanol fuels are reported in the Jacobson paper.)
Finally, the American Lung Association noted that Jacobson had not addressed the reduction in carbon dioxide emissions associated with the use of E85.
The NRDC identified what it characterized as a number of flaws with the paper, and recommended two steps to clarify the results of the paper, and take action if warranted:
First, that a team of leading vehicle emission experts review the existing data on emissions from E85. Based on this review, if the panel believes the emission scenarios in Dr. Jacobson’s study are incorrect and/or additional sensitivity runs are necessary, air pollution regulators should re-run the air pollution model to develop a broader scientific consensus of the impacts on air quality.
Second, based on the results from the above work, NRDC urged the CARB, US EPA, automakers and the ethanol industry to commit to additional testing of E85 vehicles if warranted. If such testing results indicate a need, we call upon CARB and US EPA to immediately set tighter emission standards on E85 vehicles to protect public health.
NRDC made a number of pointed comments on the contents of the paper, including:
The study finding conflicts with findings by US EPA, US DOE and NREL that found that E85 can reduce emissions of smog-forming chemicals.
The study’s assumption that E85 emissions are substantially different than those of gasoline is incorrect.
The study’s findings are primarily driven by assumed decrease in NOx.
The study ignores the potential global warming pollution reductions from E85 and the smog impact of rising temperatures caused by global warming.
In conclusion, the NRDC said,
The author’s comments surrounding the release of his study overstate what the study actually shows. An accurate summary would be that this study shows that use of high blend ethanol is unlikely to significantly improve air quality compared to use of gasoline.—NRDC
In response to all of the above plus other comments in the press and from other organizations, Jacobson published a detailed rebuttal of the various charges on his web site at Stanford (with the promise of additional rebuttal to come, as of 26 April).
As to the general charge of a misleading study due to the assumption of 100% penetration of E85, Jacobson noted:
The study makes no exaggerations as it does not claim that E85 will or is likely to make a 100% penetration. The purpose of looking at 100% penetration was to determine an upper limit of the effects from which the effects of any smaller addition of geographically-dispersed vehicles can be examined. Once the 100% effects are known, the effects of incrementally-adding a few geographically-dispersed vehicles can be estimated. It is the direction of the effects, not the magnitude, that is important in this case.
Nor was he swayed by the argument about greenhouse gases, characterizing the potential reduction, based on recent life cycle analyses, as too low. Concerning the NRDC paper, Jacobson noted:
In this document, NRDC has suppressed information contrary to its argument, misstated assumptions and conclusions in the paper, and failed to comment on the real issue, the comparative disadvantages of both ethanol and gasoline compared with other existing and emerging technologies that nearly eliminate air pollution, climate relevant gases, and use much less land area than corn or prairie grass for ethanol.
“Effects of Ethanol (E85) Versus Gasoline Vehicles on Cancer and Mortality in the United States”; Mark Z. Jacobson, Environ. Sci. Technol., ASAP Article 10.1021/es062085v S0013-936X(06)02085-2