Emission Reduction Strategies for School Buses and HDDV Trucks
A Research Study Sponsored by NJDOT

Principal Investigators:

Project Summary

It is estimated that heavy-duty diesel emissions are responsible for 80% of all particulate matter (PM) emissions and 33% of all NOx emissions from mobile sources in the northeast United States. Accordingly,the New Jersey Department of Transportation (NJDOT) has sponsored a multi-year research study at Rowan University to develop strategies for reducing diesel emissions from mobile sources such as school buses and class 8 trucks.

This web site presents the results of mobile school bus testing that has been performed to quantify the emission reduction capabilities of various alternative fuels such as biodiesel and ultra low sulfur diesel blends and exhaust aftertreatment devices such as the Johnson Matthey CRT, Lubrizol DPF and Nett Technologies DOC when applied to school buses that are representative of those currently in use in the state of NJ.

Test Procedure

Three school buses equipped with an International T444E, an International DT466E, and a Cummins 5.9L ISB engine were instrumented and tested at the Aberdeen Test Center at the Aberdeen Proving Grounds in Maryland. Exhaust gas emission measurements were made using a Semtech-D mobile emissions analyzer to measure CO, CO2, NO2, NO, O2, and unburned hydrocarbons, along with a Sensors PM-300 to measure PM. In addition to the exhaust emissions measurements, operating parameters such as instantaneous vehicle speed, engine speed, percent load and fuel flow rate were acquired from the engine electronic control module (ECM) during testing.

To ensure repeatability of testing under conditions that accurately reproduce actual school bus operating conditions, a new composite mobile school bus cycle was developed. The cycle was developed by acquiring Global Positioning System (GPS) data from actual school bus routes from 5 different municipalities within the state of New Jersey.

In addition to the mobile school bus testing, a comprehensive experimental study on emissions from school bus idling was also conducted.  To quantify emissions and fuel consumption during idling, the three school buses were instrumented and tested in an environmental chamber. To simulate a wide variety of idling situations, tests were conducted at four different ambient temperatures (20°F, 40°F, 65°F and 85°F) and relative humidity ranging from 37 to 90%. Exhaust gas emission measurements were made using the Semtech-D and Sensors PM-300. Using the results of this study, a new NOx humidity/temperature correlation was developed for use in the mobile tests.

Biodiesel Emissions Results

It has been well documented that biodiesel and biodiesel blends are effective in reducing CO, HC, and PM emissions; decreasing dependence on petroleum imports; and developing new markets for agricultural products such as soybeans. However, most studies have also shown that NOx emissions from diesel engines increase when the percentage of biodiesel in the fuel blend is increased. The perceived NOx penalty associated with biodiesel threatens to limit its widespread acceptance since engine manufacturers and environmental regulators alike continue to struggle with NOx emissions from mobile diesel sources. However, several more recent studies have shown that, under realistic operating conditions, NOx emission increases are negligible for a variety of diesel engine and vehicle types operating on 20% biodiesel (B20).

In the present work, a comprehensive study of school buses was conducted to quantify actual in-use emissions during realistic drive cycles using biodiesel blends. On-road studies were conducted using the Medford, NJ school bus fleet in which three B20 buses and a control bus were tested using an identical school bus route. Next, three school buses were instrumented and tested on a test track at the Aberdeen Test Center using the Rowan University Composite School Bus Cycle. Exhaust gas emission measurements were made using a Sensors Semtech-D along with a Sensors PM-300 to measure particulate matter. Results show that the Medford school buses actually exhibited a reduction in NOx emissions. The school buses tested at Aberdeen exhibited very little NOx increase and in some cases exhibited slight decreases in NOx. The study suggests that B20 can be incorporated with little or no NOx penalty in a variety of mobile applications.

Link to the Rowan University Partnership for Clean NJ School Bus web site.

Publications

Marchese, A. J., Hesketh, R. P, Colligan, S., Toback, A. and Mensch, A. (2005). NOx Emission from Biodiesel Powered Vehicles during Realistic In-Use Driving Conditions. Fall Technical Meeting of the Eastern States Section of the Combustion Institute, Orlando, FL, Novermber 2005.

Hearne, J., Toback, A., Marchese, A.J., Hesketh, R. P. (2005). Development of a New Composite School Bus Test Cycle and the Effect of Fuel Type on Mobile Emissions from Three School Buses. 2005 SAE World Congress, Detroit, MI. SAE 2005-01-1616

Toback, A., Hearne, J., Marchese, A.J., Hesketh, R. P. (2005). Experimental Evaluation of Aftertreatment Devices on Mobile School Bus Emissions from Diesel Powered School Buses. 2005 SAE World Congress, Detroit, MI. SAE 2005-01-1757.

Hearne, J. (2004). School Bus Idling and Mobile Diesel Emissions Testing: Effect of Fuel Type and Development of a Mobile Test Cycle.  Master's Thesis, Rowan University.

Toback, A., Hearn, J., Akers, J., Hesketh, R. P. and Marchese, A. J. (2004). Diesel Emission Reduction Strategies for School Buses: Idle and Mobile Emissions Test Results.  AIChE 2004 Spring National Meeting and Process Industries Exposition. New Orleans, LA.

Marchese, A. J. and Hesketh, R. P. (2003). School Bus Diesel Emissions: Experimental Results from Mobile and Idle Testing.  New Jersey Department of Transportation, 5th Annual Research Showcase.  October 24, 2003.

Kuritz, B., Hearne, J., Marchese, A.J., Hesketh, R. P. (2004).  Application of Experimental Design in the Steady State Particulate Exposure Levels in a 1992 International School Bus.  2004 SAE World Congress, Detroit, MI. SAE 2004-02-1088.

Toback, A., Ginn, J., Hearne, J., Marchese, A.J., Hesketh, R. P. (2004). Life Cycle Analysis of Heavy Duty Diesel Vehicle Idling Alternatives. 2004 SAE World Congress, Detroit, MI. SAE 2004-01-0637.

Toback, A., Hearne, J., Kuritz, B., Marchese, A.J., Hesketh, R. P. (2004). The Effect of Ambient Temperature and Humidity on Idling Emissions from Diesel School Buses.  2004 SAE World Congress, Detroit, MI. SAE 2004-01-1087.

R. P. Hesketh, B. Kuritz, J. Hearne, A. J. Marchese, “The Impact of Alternative Fuels on Diesel Emissions,” ECI Conference on Green Engineering:  Defining the Principles,  San Destin, Florida May 18 – 22, 2003.

Ginn, J., Hesketh, R.P. and Marchese, A. J. (2003). LCA Analysis of Idle Reduction Technologies for Diesel Engines.  AIChE 2003 Annual Meeting.

Pekula, N., Kuritz, B., Hearne, J., Marchese, A.J., Hesketh, R. P. (2003). The Effect of Ambient Temperature and Humidity on Idling Emissions from Heavy Duty Diesel Trucks.  2003 SAE World Congress, Detroit, MI. SAE 2003-01-0290. 

Kuritz, B., Hearne, J., Marchese, A.J., Hesketh, R. P. (2003).  Evaluation of Alternative Fuels using Mobile Diesel Emissions Testing. AIChE 2003 Spring National Meeting and Process Industries Exposition. New Orleans, LA.

Marchese, A. J. and Hesketh, R. P. (2002). Diesel Emission Reduction Strategies for HDDV Truck Idling.  New Jersey Department of Transportation, 4th Annual Research Showcase.  November 1, 2002.

Hesketh, R. P.  and Marchese, A. J. (2002). On-Board Exhaust Emissions and Cabin Particulate Matter Measurements for Diesel Powered School Buses. New Jersey Department of Transportation, 4th Annual Research Showcase.  November 1, 2002.

Project Personnel

Robert Hesketh, PI

Anthony Marchese, PI

Stewart Slater, PI

Sarina Colligan, '04, ChE, Graduate Student

Jason Hearne, '02, '04, ME Graduate Student

Brian Kuritz, '02, '04, ChE Graduate Student 

Brook Sirchio, '03, ChE

Andy Toback, '03, ChE Graduate Student

Craig Agin, '03, CEE

Mike Collarin, '03, ME

Mike Melniczuk, '03, ME

Sam Zammarrelli, '04, ME

Nick Pekula, '03, ME

Jennifer Akers, '03, ME

Jamie Ginn, '04, ChE

Ed Trasferini, '03, ME

Cliff Amundsen, '03, I.I.T.

Last Updated: May 16, 2005