Hybrids
Hybrid-electric transit bus technology has progressed significantly over the last five years. In 1999, when NAVC initiated the first independent tests of hybrid bus emissions and fuel economy, there was only one commercially available product in the U.S. Today, U.S. transit operators have a choice of at least six commercially available hybrid bus products, with more entering the market. There are over ten transit agencies running commercial hybrid buses, with major orders in process at New York City MTA and King County in Seattle. As transit operators are increasingly being asked to reduce the environmental impact of their fleets, hybrid buses will be an important option to consider.
The NAVC has developed a primer on hybrid technology for transit buses: Hybrid Bus Technology Primer
Overview of NAVC Hybrid Bus Activities
The NAVC actively promotes the successful deployment of hybrid bus technologies.
National Heavy-Duty Hybrid Working Group
In 2000, the NAVC initiated the U.S. Heavy-Duty Hybrid Working Group, as a result of emission and fuel economy testing conducted by the NAVC on hybrid buses (see Emissions Testing below). The Hybrid Work Group brings together hybrid system developers and integrators, transit operators, engine manufacturers, bus companies, energy storage/management developers, federal and state regulators, testing laboratories and others interested in promoting hybrid bus technology. This Working Group has undertaken two major initiatives designated by group members as potential barriers to hybrid bus deployment that can be addressed collaboratively.
The NAVC Work Group's first produced the Engine Certification Recommendations Report, which sought to address the potential barrier of hybrid bus certification. This report analyzed in-use hybrid-electric engine data to recommend an alternate engine cycle for emissions certification testing.
Next, the NAVC initiated and managed a collaborative effort between the Hybrid Work Group and the Society of Automotive Engineers (SAE) to develop J2711, a recommended practice for heavy-duty hybrid and electric vehicle emissions and fuel economy testing. J2711 was published by SAE in 2002.
- J2711 is available only from the SAE website: www.sae.org
Heavy-Duty Emissions Testing Project
In 1999, the NAVC initiated Initiated and managed the first independent and comprehensive testing of heavy-duty hybrid buses for emissions. This project was developed to assist state and local agencies, transit operators and industry stakeholders in assessing emissions and fuel efficiency of hybrid-electric technologies in heavy-duty transit applications. NAVC designed and managed this project to test alternative fuel and hybrid-electric transit buses for emissions and fuel efficiency on a chassis dynamometer.
The program focused primarily on determining and extrapolating the performance levels of hybrid-electric technologies compared to their conventional counterparts in terms of fuel economy and emissions. The final report was widely disseminated in the transit and hybrid worlds, and the test results continue to be cited by hybrid bus developers, government agencies, and others. The NAVC publicized this report at various conferences for transit operators, such as APTA bus conferences and SAE Toptecs.
Author, TCRP Report 59 Hybrid-Electric Transit Buses: Status, Issues and Benefits
In 1999, the NAVC was selected by TCRP to develop a report on hybrid buses for transit operators. At this time, hybrid technology was relatively new, with only a small number of commercial buses available. The NAVC wrote a report that provided information on the state-of-the-art of hybrid bus technology and explained the details of hybrid systems, and the various elements that could be incorporated into hybrid systems.
The NAVC also researched several existing hybrid bus deployments in order to provide "case studies" for transit operators interested in seeing how the technology works in real service. The report also provided basic analysis on life-cycle costs, although, at this time, there was limited data available for such an analysis. The report also provided the results of the NAVC's emissions and fuel economy testing project described above.
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