Dr. Stephen Rattien

Executive Director

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

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