Exhaust Emission Effects of Fuel Sulfur and Oxygen on Gasoline Nonroad Engines

摘要

The purpose of this memo is to document the effects of changing gasoline specifications on exhaust emissions from nonroad gasoline-fueled engines that are incorporated in EPA's draft NONROAD2004 emissions inventory model. There have been a number of gasoline specifications that have changed or have been considered for change in the past few years. The most prominent of these changes has been summer volatility restrictions, wintertime oxygenated fuel requirements, and reformulated gasoline requirements which incorporate year-round oxygenate requirements and summertime emission requirements. For reasons described below, the effect of these fuel changes on nonroad gasoline engines' exhaust emissions of carbon monoxide (CO), nitrogen oxides (NOx), and volatile organic compounds (VOC) is ascribed mainly to the oxygen content. Any expected changes to the fuel sulfur is expected to reduce SOx emissions only.