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HYBRID ELECTRIC SCHOOL BUS PRELIMINARY TECHNICAL FEASIBILITY REPORT Ewan Gareth David Pritchard, P.E.

HYBRID ELECTRIC SCHOOL BUS
PRELIMINARY TECHNICAL FEASIBILITY REPORT



Ewan Gareth David Pritchard, P.E.
Hybrid Electric School Bus Program Manager
Advanced Energy Corporation
Raleigh, NC



Revision 1.3
September 14, 2004








ACKNOWLEDGEMENTS
A lot of effort has gone into the Hybrid Electric School Bus project. The advisory
group now has almost 30 members from school bus agencies, environmental groups,
academia, and manufacturers, I would like to thank all of them for their involvement and
dedication to the project and encourage all of them to keep up the support, we have a long
way to go.
In particular I would like to thank the individual agencies and individuals providing
critical school bus data, Ben Matthews and Derek Graham of the NC Department of
Public Instruction, Bill Schroyer of the Florida Department of Education, Ralph Knight
of the Napa Valley Unified School District, Marshall Casey and Donald Tudor of the
South Carolina Department of Education and Ken Dodson of Thomas Built Bus. Thanks
to Dr. Richard Johnson of North Carolina State University, who provided critical insight
into the analysis of the models. Thanks to Advanced Energy for their support of
innovative projects and for the atmosphere of creativity that has helped this project exist.
Also to the many staff at Advanced Energy that worked hard to make this document clear
and concise, Nicole Kaufman, Lisa Manuel, Sharon Gladwell, Jodie Lanning and Jason
Giaquinto. I would especially like to thank the agencies that are funding the hybrid
school bus feasibility study, of which this is a small part. Thanks to the North Carolina
Energy Office, Duke Power, and Progress Energy.

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TABLE OF CONTENTS

LIST OF TABLES............................................................................................................ III
LIST OF FIGURES ........................................................................................................... V
EXECUTIVE SUMMARY ................................................................................................ 1
1. INTRODUCTION ...................................................................................................... 3
1.1 Background............................................................................................................. 3
1.2 Vehicle
Losses ........................................................................................................ 6
1.3 Emissions ................................................................................................................ 8
1.4 ADVISOR............................................................................................................. 12
2. BASELINE SCHOOL BUS MODELING ............................................................... 13
2.1 Parameters............................................................................................................. 14
2.2 Route ..................................................................................................................... 21
2.3 Performance .......................................................................................................... 25
2.4
Baseline Fuel Economy and Emissions ................................................................ 26
2.5 Model
Sensitivity.................................................................................................. 27
3. SERIES HYBRID MODEL...................................................................................... 28
3.1 Component
Sizing................................................................................................. 29
3.2
Series System Summary ....................................................................................... 34
4. PARALLEL
HYBRID
MODEL............................................................................... 35
4.1 Component
Sizing................................................................................................. 36
4.2 Parallel
System
Summary ..................................................................................... 39
5. PLUG-IN HYBRID MODELS................................................................................. 40
6. CONCLUSIONS....................................................................................................... 54
REFERENCES ................................................................................................................. 56
APPENDIX A. ABBREVIATIONS.............................................................................. 58
APPENDIX B. GLOSSARY......................................................................................... 59
APPENDIX C. MODEL RESULTS ............................................................................. 60
APPENDIX D. MODEL DATA FILES........................................................................ 63

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iii
LIST OF TABLES
Table 2.1. Chassis Specifications ..................................................................................... 14
Table 2.2. Baseline Bus Specifications............................................................................. 15
Table 2.3. Transmission Specifications ............................................................................ 18
Table 2.4. Accessory Loads.............................................................................................. 19
Table 2.5. Performance Results ........................................................................................ 25
Table 2.6. Fuel Economy and Emission Results .............................................................. 26
Table 2.7. Point Variable Sensitivity to Select Variables................................................. 27
Table 3.1. Series Hybrid System Specifications............................................................... 34
Table 4.1. Parallel Hybrid System Specifications ............................................................ 39
Table 5.1. Plug-in Hybrid Electric Models....................................................................... 41
Table 5.2. EIA Reported 2002 North Carolina Power Plant Data.................................... 42
Table C.1. Battery Pack Usage ......................................................................................... 60
Table C.2. Acceleration Results ....................................................................................... 60
Table C.3. Additional Performance Results ..................................................................... 61
Table C.4. Fuel Economy and Emission Results.............................................................. 61
Table C.5. Fuel Cost Chart ............................................................................................... 62

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LIST OF FIGURES
Figure 1.1. Instantaneous power needs during a representative trip................................... 4
Figure 1.2. Power flow in a series hybrid vehicle .............................................................. 4
Figure 1.3. Basic ADVISOR Block Diagram................................................................... 12
Figure 2.1. Engine Torque Curves.................................................................................... 16
Figure 2.2. Engine Power Curves ..................................................................................... 17
Figure 2.3. City Suburban Heavy Vehicle Cycle.............................................................. 21
Figure 2.4. Suburban Route from ITRE Study ................................................................. 22
Figure 2.5. Urban Route from ITRE Study ...................................................................... 22
Figure 2.6. West Virginia Suburban Cycle...................................................................... 23
Figure 2.7. CSHVC Distribution ...................................................................................... 24
Figure 2.8. West Virginia Suburban Distribution............................................................. 24
Figure 2.9. ITRE Suburban Route Distribution................................................................ 24
Figure 2.10. ITRE Urban Route Distribution ................................................................... 24
Figure 3.1. Series Hybrid Electric Schematic................................................................... 28
Figure 3.2. Motor/Controller Operating and Efficiency Curves....................................... 32
Figure 4.2. Parallel Hybrid Electric Schematic ...............