REVIEW OF PRIOR STUDIES OF FUEL EFFECTS ON VEHICLE EMISSIONS

CRC Project No. E-84

Leader:      C. H. Schleyer

Scope and Objective

The objective of the project is to conduct a comprehensive review of published studies of fuel property effects on vehicle exhaust emissions.  A contract was established in December 2007 with Dr. Albert Hochhauser, ExxonMobil (retired), to conduct Project E-84, which will cover gasoline light-duty vehicles, diesel light and heavy-duty vehicles, and non-road engines. The intent of the study was to update previous reviews conducted by Koehl, et al. on light-duty gasoline and by Pedley, et al. on heavy-duty diesel. Highest priority was given to studies published after these reviews and to vehicle technologies that make up the bulk of the current and future U.S. vehicle fleet.

Current Status and Future

While the highest priority was given to studies covering U.S. vehicles, fuels and emission testing procedures, relevant studies from Europe, Japan and other regions were also reviewed as available. Emphasis was on published studies using established government/industry emission measurement procedures simulating in-use vehicle operation and with well-designed test fuel matrices with independent variation in one or more fuel properties that allow individual fuel property effects to be evaluated.

Fuel properties will include regulated properties or those covered in the reviews of Koehl, et al. and Pedley, et al. For gasoline, key fuel properties include RVP, sulfur, distillation properties, oxygenate, aromatics, benzene, and olefins. For diesel, key fuel properties are cetane number (natural and additized), aromatics, density, and distillation. Other properties were considered if experimental information indicated that they had a significant impact. The impact of vehicle technology on fuel effects including emission control technology was also considered. The study included mass emissions of criteria pollutants NMHC, NOx, CO and PM, and HC speciation effects including air toxics and ozone formation potential.

The Final Report was released in September 2008 and is available on the CRC Website.

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