Dr. Stephen Rattien
Commission on Geosciences, Environment and Radiation
National Research Council
2100 Constitution Ave. N.W. Washington, D.C. 20418
Dear Dr. Rattien:
I understand that the Environmental Protection Agency has requested an evaluation of "whether the existing data is sufficient to show that adding ethanol to RFG on the basis of reactivity would not adversely impact the in-use environmental. benefits of the RFG program" and that it has also requested your advice on what additional information would be necessary to allow such a determination to be made. EPA's request is related to a proposal for fuel certification which I discussed at a meeting with Assistant Administrator Mary D. Nichols in November, 1993.
On September 28, 1995 I convened a hearing of the Senate Committee on Agriculture, Nutrition and Forestry on the role of ethanol in the reformulated gasoline program. At that hearing, I discussed EPA's proposal for a National Academy of Sciences (NAS) study with Administrator Carol Browner. Our Committee hearing was called to discuss the restraints which current EPA policies place on refiners who wish to use ethanol blends in reformulated gasoline and the effect of reduced ethanol use on the farm economy and on deficiency payments. Under the RFG program, the EPA Judges fuel blends solely by their total mass of emissions of volatile organic compounds ("VOCs"). Since the addition of ethanol to gasoline increases volatility—and thus increases "evaporative" VOCs—it is difficult for regular ethanol blends to qualify absent the use of special low RVP Gasoline which is more expensive and unavailable in many markets.
However, if one considers the actual ozone forming potential of ethanol blends and not Just their mass of emissions, a case can be made that certain ethanol blends may produce reductions in VOCs which are just as great as those produced by qualifying nonsthanol blends. Because 10% ethanol blends have greater oxygen content, they may emit fewer exhaust VOCs than non-ethanol
blends. And since exhaust VOCs are believed to have a greater propensity to form Ozone than evaporative VOCs, the greater reduction in exhaust VOCs achieved by certain ethanol RFG blends may counterbalance their greater mass of evaporative VOCs. Furthermore, because of the additional oxygen, these blends may contain less carbon monoxide than non-ethanol blends, further reducing their tendency to form ozone since carbon monoxide is a recognized precursor of ozone.
I have proposed that EPA establish a procedure to certify ethanol blends as equivalent to non-ethanol blends under section 211 (k) (4) (B) of the Clean Air Act, but EPA has so far refused to do so bemuse it is unsure clot there is an appropriate methodology for making the comparison.
I hope that the NAS Study will have a practical aim; that is, it will help to determine, in light of the best available information, the procedures (i.e., the data and analysis) by which the equivalency of two blends could be determined with a reasonable degree of certainty. To the extent that additional information or studies are necessary before such procedures can be developed or implemented, I also hope that NAS will identify the additional information and analyses which would be needed and Chat it would work with the EPA and with ocher concerned parties to ensure that it is provided.
The NAS study is critical to the implementation of the Clean Air Act in a manner that allows renewable fuels to play an important role in the reformulated gasoline program. I therefore Join EPA in urging the National Academy of Sciences to undertake this effort and I urge that it be completed at the earliest possible date. If you have any questions, please contact me or Jeff Burnam of my staff at 202-224-7443.