Assessment of Hybrid-Electric Transit Bus Technology (2009)

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TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2009 www.TRB.org T R A N S I T C O O P E R A T I V E R E S E A R C H P R O G R A M TCRP REPORT 132 Research sponsored by the Federal Transit Administration in cooperation with the Transit Development Corporation Subject Areas Public Transit Assessment of Hybrid-Electric Transit Bus Technology Nigel N. Clark Feng Zhen W. Scott Wayne WEST VIRGINIA UNIVERSITY Morgantown, WV I N A S S O C I A T I O N W I T H John J. Schiavone Cliff Chambers Aaron D. Golub TRANSIT RESOURCE CENTER Winter Springs, FL Kevin L. Chandler BATTELLE MEMORIAL INSTITUTE Columbus, OH

TCRP REPORT 132 Project C-15 ISSN 1073-4872 ISBN 978-0-309-11803-3 Library of Congress Control Number 2009937401 © 2009 Transportation Research Board COPYRIGHT PERMISSION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FTA, or Transit Development Corporation endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. NOTICE The project that is the subject of this report was a part of the Transit Cooperative Research Program conducted by the Transportation Research Board with the approval of the Governing Board of the National Research Council. Such approval reflects the Governing Board’s judgment that the project concerned is appropriate with respect to both the purposes and resources of the National Research Council. The members of the technical advisory panel selected to monitor this project and to review this report were chosen for recognized scholarly competence and with due consideration for the balance of disciplines appropriate to the project. The opinions and conclusions expressed or implied are those of the research agency that performed the research, and while they have been accepted as appropriate by the technical panel, they are not necessarily those of the Transportation Research Board, the National Research Council, the Transit Development Corporation, or the Federal Transit Administration of the U.S. Department of Transportation. Each report is reviewed and accepted for publication by the technical panel according to procedures established and monitored by the Transportation Research Board Executive Committee and the Governing Board of the National Research Council. The Transportation Research Board of the National Academies, the National Research Council, the Transit Development Corporation, and the Federal Transit Administration (sponsor of the Transit Cooperative Research Program) do not endorse products or manufacturers. Trade or manufacturers’ names appear herein solely because they are considered essential to the clarity and completeness of the project reporting. TRANSIT COOPERATIVE RESEARCH PROGRAM The nation’s growth and the need to meet mobility, environmental, and energy objectives place demands on public transit systems. Current systems, some of which are old and in need of upgrading, must expand service area, increase service frequency, and improve efficiency to serve these demands. Research is necessary to solve operating problems, to adapt appropriate new technologies from other industries, and to intro- duce innovations into the transit industry. The Transit Cooperative Research Program (TCRP) serves as one of the principal means by which the transit industry can develop innovative near-term solutions to meet demands placed on it. The need for TCRP was originally identified in TRB Special Report 213—Research for Public Transit: New Directions, published in 1987 and based on a study sponsored by the Urban Mass Transportation Administration—now the Federal Transit Administration (FTA). A report by the American Public Transportation Association (APTA), Transportation 2000, also recognized the need for local, problem- solving research. TCRP, modeled after the longstanding and success- ful National Cooperative Highway Research Program, undertakes research and other technical activities in response to the needs of tran- sit service providers. The scope of TCRP includes a variety of transit research fields including planning, service configuration, equipment, facilities, operations, human resources, maintenance, policy, and administrative practices. TCRP was established under FTA sponsorship in July 1992. 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Once selected, each project is assigned to an expert panel, appointed by the Transportation Research Board. The panels prepare project state- ments (requests for proposals), select contractors, and provide techni- cal guidance and counsel throughout the life of the project. The process for developing research problem statements and selecting research agencies has been used by TRB in managing cooperative research pro- grams since 1962. As in other TRB activities, TCRP project panels serve voluntarily without compensation. Because research cannot have the desired impact if products fail to reach the intended audience, special emphasis is placed on dissemi- nating TCRP results to the intended end users of the research: tran- sit agencies, service providers, and suppliers. TRB provides a series of research reports, syntheses of transit practice, and other support- ing material developed by TCRP research. APTA will arrange for workshops, training aids, field visits, and other activities to ensure that results are implemented by urban and rural transit industry practitioners. The TCRP provides a forum where transit agencies can cooperatively address common operational problems. The TCRP results support and complement other ongoing transit research and training programs. Published reports of the TRANSIT COOPERATIVE RESEARCH PROGRAM are available from: Transportation Research Board Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet at http://www.national-academies.org/trb/bookstore Printed in the United States of America

CRP STAFF FOR TCRP REPORT 132 Christopher W. Jenks, Director, Cooperative Research Programs Crawford F. Jencks, Deputy Director, Cooperative Research Programs Lawrence D. Goldstein, Senior Program Officer Eileen P. Delaney, Director of Publications Hilary Freer, Senior Editor TCRP PROJECT C-15 PANEL Field of Engineering of Vehicles and Equipment John Attanucci, Massachusetts Institute of Technology, Cambridge, MA (Chair) Woodrow W. Clark, II, Clark Strategic Partners, Beverly Hills, CA Lee Kemp, Denver Regional Transportation District, Denver, CO Gary LaBouff, Metropolitan Transportation Authority—New York City Transit, Department of Buses, New York, NY Francis Martin Mellera, III, San Francisco Municipal Transportation Agency, Murphys, CA James D. Pachan, Los Angeles County Metropolitan Transportation Authority, Los Angeles, CA Darryl Spencer, Dallas Area Rapid Transit, Dallas, TX John G. Bell, FTA Liaison Carlos Garay, FTA Liaison Lurae Stuart, APTA Liaison Kevin Walkowicz, National Renewable Energy Laboratory Liaison Peter Shaw, TRB Liaison AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under TCRP Project C-15 and was led by the Department of Mechanical and Aerospace Engineering at West Virginia University (WVU), with major subcontract support from the Transit Resource Center (TRC), and Battelle Memorial Institute. Nigel N. Clark, Professor and Berry Chair of Engineering at WVU, was the project director and prin- cipal investigator. The other authors of this report were John J. Schiavone, project manager and senior consultant at TRC, and W. Scott Wayne, assistant professor of mechanical and aerospace engineering at WVU, who were co-principal investigators; Feng Zhen, research assistant and PhD candidate at WVU; Kevin L. Chandler, project manager at Battelle; Cliff Chambers, principal at TRC, and Aaron D. Golub, consultant at TRC and assistant professor at the School of Planning and School of Sustainability, Arizona State University. Donald W. Lyons, Mridul Gautam, Gregory J. Thompson, and the staff of the Center for Alternative Fuels, Engines and Emissions at WVU provided valuable input for the C-15 program model. This report and the C-15 program greatly benefited from the assistance of the managers and staff at six transit agencies (New York City Transit, King County Metro, Washington Metropolitan Area Transit Authority, Long Beach Transit, Dallas Area Rapid Transit, and OC Transpo [Ottawa, Canada]), and three hybrid drive original equipment manufacturers (Allison Transmission, BAE Systems, and ISE Corpora- tion). Significant data used in the C-15 program were gathered through a program funded by the U.S. Department of Energy, conducted by the National Renewable Energy Laboratory (NREL, in Golden, CO), with support from Battelle. C O O P E R A T I V E R E S E A R C H P R O G R A M S

TCRP Report 132: Assessment of Hybrid-Electric Transit Bus Technology provides decision- making guidelines coupled with a comprehensive life cycle cost model (LCCM) to assist tran- sit managers in evaluating, selecting, and implementing hybrid-electric technology options for transit buses. The guidelines and the accompanying LCC model resulted from the gathering of site data coupled with a comprehensive review of both capital requirements and operating costs of hybrid-electric buses in comparison with those powered by traditional diesel engines. Infor- mation grew out of a sound, engineering-based, independent technical evaluation of the costs, performance, and reliability of hybrid-electric transit bus technology in actual service. The LCC model, contained on the accompanying CD-ROM (CRP-CD-71), allows the user to compare the total life cycle costs across several cost categories for up to 6 different “purchase scenarios.” These scenarios let the user decide when the purchases will be made, the types of buses to be compared, the work load of the buses, and many other cost inputs in determining benefits and costs associated with alternative purchasing strategies. The next generation of new bus-propulsion technology is arriving. Hybrid-electric buses are being promoted as more cost effective; more reliable; more energy efficient than con- ventional diesel and superior to alternative fuel options (e.g., compressed natural gas, liquefied natural gas, propane); and more environmentally friendly. Based on a complex set of alternatives, there is a need to analyze emerging propulsion technologies to assist transit agencies considering hybrid-electric buses. For several decades transit buses, usually of 40-foot length, have traditionally been pow- ered by diesel engines and driven using automatic transmissions. Over the last 15 years, how- ever, various transit systems have begun to use an assortment of alternative fuels, often while the technologies were under development. Use of alternative fuels has met with varying degrees of success. Based on an increasing need to improve fuel economy while reducing tailpipe emissions, alternate bus powertrain configurations have entered the marketplace and are expected to evolve over the next decade. This report examines developing technology and life cycle cost (LCC) for transit buses using conventional drivetrains with diesel or natural gas engines, and hybrid-electric buses with diesel or gasoline engines. The analysis includes a review of literature pertaining to (a) hybrid bus architecture and energy storage choices and (b) a comparison of existing fuel economy and emissions data for competing technologies. Published data demonstrated that diesel hybrid-electric buses produced lower emissions and consumed less fuel than diesel buses. The study gathered hybrid-electric bus performance data for real-world bus operations at four sites (New York; Seattle; Long Beach, CA; and Washington, DC), along with data for conventional diesel and natural gas buses to provide a comparison. Seattle buses were F O R E W O R D By Lawrence D. Goldstein Staff Officer Transportation Research Board

60 feet in length, with the remaining study buses having a length of 40 feet. Further infor- mation on bus purchase cost, maintenance cost, and rebuild cost was obtained by con- sulting manufacturers. A comprehensive bus LCCM was developed in spreadsheet format and used to evaluate transit bus LCC performance, considering both capital and operating costs. This LCC model includes default values and incorporates fuel price projections and a fuel economy model. Default values used in the report may be employed by a transit agency for initial planning purposes and fleet selection, but the model is set up to allow tran- sit operators with more sophisticated data available to optimize route assignments for spe- cific bus technologies, to minimize the cost of operating a mix of technologies in the fleet, to appreciate the impacts of variables such as fuel cost on future operation, and to deter- mine when bus replacement is most desirable from a cost perspective. Major findings are that bus routes, characterized by average speed, have a profound effect on determining the cost advantage of hybrid buses, which offer greatest efficiency advantage during slow, tran- sient operation. In response, the LCC model can be used to determine the threshold speed for which hybrid and conventional buses have equivalent life cycle cost, based on fuel prices. Unpredictable future fuel pricing is the greatest enemy of reliable life cycle cost prediction. In addition, cost of facilities adversely impacts adoption of small fleets of compressed nat- ural gas buses. The report provides a strong foundation for transit system managers; policymakers; operations and maintenance professionals; and others considering the deployment of, or conversion to, hybrid-electric transit buses who wish to build a dedicated decision-making model for a specific metropolitan area. Coupled with application of the LCC model, it will also provide an impartial resource to facilitate productive discussion between public inter- est groups, city leadership, and transit system managers.

C O N T E N T S 1 Summary 4 Chapter 1 Background 4 1.1 Problem Statement and Research Objective 4 1.2 Research Approach 5 1.3 Hybrid Technologies and Test Sites 5 1.4 Brief Review of Hybrid-Electric Bus Technology 9 Chapter 2 Life Cycle Cost Model Development 9 2.1 Overview and Test Site Evaluation Summary 9 2.2 Life Cycle Cost Model 33 2.3 Abbreviated User Instructions for the LCCM 35 2.4 Testing and Execution of the LCCM 71 Chapter 3 Conclusions and Suggested Research 71 3.1 Conclusions 72 3.2 Suggested Future Research 73 References 74 Appendices and Toolkit 75 Acronyms and Abbreviations