A literature review was conducted to survey recent research on the effects of fuel properties on exhaust emissions from gasoline and diesel vehicles, on-road and off-road. Most of the literature has been published in SAE papers, although data have also been reported in other journals and government reports. A full report and database are available from the Coordinating Research Council (
www.crcao.org).
The review identified areas of agreement and disagreement in the literature and evaluated the adequacy of experimental design and analysis of results. Areas where additional research would be helpful in defining fuel effects are also identified.
In many of the research programs carried out to evaluate the effect of new blendstocks, the fuel components were splash blended in fully formulated fuels. This approach makes it extremely difficult to determine the exact cause of the emissions benefit or debit. Much of the research on Fischer-Tropsch liquids and fatty acid esters falls into this category.
A summary of effects for gasoline and diesel vehicles is shown in the accompanying tables.
The decision to carry out additional research on impacts of fuel properties should depend on the introduction of new technology, potential benefits and costs of fuel regulations, and the potential enablement of emission control systems.