Operational Evaluation of Emissions and Fuel Use of B20 Versus Diesel Fueled Dump Trucks

Diesel vehicles contribute substantially to statewide emissions of NOx, an ozone precursor, and to particulate matter. North Carolina Department of Transportation (NCDOT) is conducting a pilot study to demonstrate the use of B20 biodiesel fuel on approximately 1,000 vehicles in selected areas of the state; there are plans to extend the use of B20 fuel to a much larger number of vehicles in all 100 counties in North Carolina. Real-world in-use on-road emissions of selected heavy duty diesel vehicles, including those fueled with B20 biodiesel and petroleum diesel, were measured during normal duty cycles using a portable emissions measurement system (PEMS). Four categories of dump trucks were selected for testing, including: (1) single rear axle with Tier 1 engines; (2) single rear axle with Tier 2 engines; (3) tandems with Tier 1 engines; and (4) tandems with Tier 2 engines. A total of 12 vehicles were tested. Each vehicle was tested for one day on B20 biodiesel and for one day on petroleum diesel, for a total of 24 days of field measurements. The vehicles were operated by drivers assigned by NCDOT. Each test was conducted over the course of an entire workshift, and on average there were 4.5 duty cycles per shift. Each duty cycle is comprised of a uniquely weighted combination of nine operating modes (idle, three levels of acceleration, three levels of cruise, deceleration, and dumping). Average emission rates on a mass per time basis varied substantially among the operating modes. Average fuel use and emissions rates increased 26 to 35% when vehicles were loaded versus unloaded. Average fuel use and CO2 emission rates were approximately the same for the two fuels, but average emission rates of NO, CO, HC, and PM decreased by 10, 11, 22, and 10%, respectively, for B20 biodiesel versus petroleum diesel. The average emission rates from the PEMS data were compared with engine dynamometer data. The two data compared reasonably well and appropriately. The role of real world duty cycles, as opposed to arbitrary test cycles, was found to be critical with respect to accurate estimation of emissions, especially for NO. Factors that were responsible for the observed variability in fuel use and emissions include: operating mode, vehicle size, engine type, vehicle weight, and fuel. In some cases, the type of engine clearly had a significant role. In particular, NO and PM emission rates were typically lower for Tier 2 engines than for Tier 1 engines. Recommendations were made regarding operating strategies to reduce emissions, choice of fuel, and the need for future work to collect real world duty cycle data for other vehicle types.

  • Record URL:
  • Supplemental Notes:
    • This research was funded by the U.S. Department of Transportation, University Transportation Centers Program.
  • Corporate Authors:

    North Carolina State University, Raleigh

    Center for Transportation and the Environment, Centennial Campus, Box 8601
    Raleigh, NC  United States  27695-8601

    North Carolina State University, Raleigh

    Department of Civil, Construction, and Environmental Engineering
    2501 Stinson Drive, Campus Box 7908
    Raleigh, NC  United States  27695-7908

    North Carolina Department of Transportation

    P.O. Box 25201, 1 South Wilmington Street
    Raleigh, NC  United States  27611

    Research and Special Programs Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Frey, H Christopher
    • Kim, Kangwook
  • Publication Date: 2005-9

Language

  • English

Media Info

  • Media Type: Print
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 374p

Subject/Index Terms

Filing Info

  • Accession Number: 01051567
  • Record Type: Publication
  • Report/Paper Numbers: FHWA/NC/2005-07
  • Files: UTC, TRIS, USDOT, STATEDOT
  • Created Date: Jun 18 2007 11:15AM