Effect of Biodiesel on Diesel Engine Nitrogen Oxide and Other Regulated Emissions

Abstract

Abstract : This report summarizes the results of a 3-year project lead by the Naval Facilities Engineering Service Center (NFESC) to obtain emissions factors (i.e. tailpipe air pollution emissions data) from 10 types of Department of Defense (DoD) operated diesel powered engines. Emissions data was obtained from 8 vehicles, primarily buses and trucks, and 2 portable generators. All testing was performed with the engines installed in the vehicles/portable equipment. Emissions factors were determined for the engines fueled with various blends/types of biodiesel as well as a baseline fuel, either California Air Resources Board (CARB) certified Ultra Low Sulfur Diesel (USLD) (15-ppm sulfur maximum) or JP-8. CARB USLD was used since it will be required within California for on-road vehicles starting in June 2006. Biodiesel blends from 20% to 70% were tested along with 100% biodiesel. For the blended biodiesel testing, the biodiesel was mixed with USLD. Although several blends were tested, the project focused on B20 (20% biodiesel) blends, since this is the primary blend of biodiesel used in military vehicles. Testing performed on B20 fuels identified three significant results: (1) There were no consistent trends over all engines tested, (2) There were no statistically significant emissions differences found between biodiesel fuels manufactured from yellow grease or soy bean oil feedstocks, and (3) An extensive statistical analyses indicated no statistically significant differences in Hydrocarbon (HC), Carbon Monoxide (CO), Nitrogen Oxides (NOx) or Particulate Matter (PM) emissions between a B20 biodiesel manufactured at Naval Base Ventura County from yellow grease and CARB ULSD petroleum diesel. The results from this project are significantly different than those previously reported by the Environmental Protection Agency (EPA). Of particular interest is the fact that for actual DoD fleet diesel engines, there was no statistically significant increase in NOx emissions.