ARB Research Seminar

This page updated June 19, 2013

Demonstration of Advanced Battery-Electric School Bus at Napa Valley Unified School District

Bill Warf, P.E., Project Manager, Sacramento Municipal Utility District, Paul Griffith, President, Santa Barbara Electric Bus Works, Ralph Knight, Transportation Director, Napa Valley Unified School District, and Dahlia Garas, University of California, Davis

July 27, 2004
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA

Research Project


Under a contract between ARB and the Sacramento Municipal Utility District (SMUD), an advanced battery-electric drive system was installed in a Blue Bird TCEV 2000 electric school bus. The system was designed, developed, and integrated by the Santa Barbara Electric Bus Works (SBEBW) and utilizes six ZEBRA sodium-nickel chloride batteries and a Siemens drive system with ELFA inverters and motors. The bus successfully completed its first year of in-service testing by the Napa Valley Unified School District and has demonstrated performance equivalent or superior to internal-combustion engine powered school buses.

The bus has proven to be safe, reliable, and its performance is satisfactory for its assigned duty cycle of 60 miles per route. The tested performance allows a more rigorous duty cycle than that demanded by the Napa terrain and consequently no problems are anticipated with continuing service. Continued testing of the bus will provide additional performance, energy consumption, and maintenance data that will allow a more comprehensive evaluation of the technology. At this time all indications are positive.

Representatives of SMUD, SBEBW, and Napa Valley School District will present the results of the project and provide demonstration rides on the bus.

Speaker Biography

William R. Warf is a project manager at the Sacramento Municipal Utility District. Mr. Warf's other projects at SMUD include an Idle Reduction infrastructure installation at the 49er Truck-stop; idle reduction projects on truck equipment with EPRI; a Transport Refrigeration Unit research project; and a Fuel Cell APU for Heavy Duty Trucks project with ISE Research and PACCAR. In the past, Mr. Warf conducted system design for electric and hybrid-electric passenger cars at Volkswagen AG in Wolfsburg, Germany and he was General Manager of Pacific Electric Vehicles, conducting pioneering research work in light electric vehicle system design and construction. Mr. Warf has also worked in manufacturing businesses, including several years working in new product design at Peterbilt Motors division of PACCAR in Newark, California.

Paul Griffith is President of the Santa Barbara Electric Bus Works and of the Santa Barbara Electric Transportation Institute. Mr. Griffith has spent twenty-four years in engineering research and development activities with the Santa Barbara MTD, Patec Corporation, Oerlikon-Contraves of Switzerland, and General Dynamics Corporation, Convair Division. He is past Chair of the National Electric Vehicle Infrastructure Working Council, is the author of numerous technical reports covering electric-bus technologies, and holds five U.S. and foreign patents for aerospace products currently under manufacture in Europe. Mr. Griffith received his Bachelor of Science degree in Mechanical Engineering from the University of California at Santa Barbara.

Ralph Knight is Director of Transportation for Napa Valley Unified School District. With over 30 years in school transportation, he has played a major part in applying new technologies to pupil transport. Previously, while working for the Petaluma District, he oversaw the introduction of the second electric school bus in the State of California. Within a few months of his arrival in Napa, he opened the door for further major changes in school transportation by incorporating two electric buses in that fleet. Mr. Knight also moved to replace all but five of the fleet's diesel powered school buses over the next five years. Currently, NVUSD is the only district in the state that is a 100 percent CNG school bus fleet, not including its three electric buses. At present, those buses are the only electric school buses operating in the U.S.

Dahlia Garas is currently finishing her Master's thesis comparing advanced battery technologies at the University of California at Davis (UCD). Her research and studies have emphasized hybrid electric vehicles. For the past four years, she has participated in the international Future Truck Hybrid Electric Vehicle Design competition held between 15 universities. Ms. Garas actively participated in training the student volunteers, administered group meetings, and fostered team organization. She was also involved in many publicity and outreach programs to introduce potential engineering students and the general public to the Future Truck program and the benefits of hybrid vehicles. She has also worked on various mechanical design projects dealing with advanced materials, including the design of composite battery enclosures and cooling systems for the current vehicle. Her other interests include biomechanics, and after graduation this fall she plans to seek a mechanical engineering position related to either advanced energy systems or biomechanics.

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