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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2018. Battery Electric Buses—State of the Practice. Washington, DC: The National Academies Press. doi: 10.17226/25061.
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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2018. Battery Electric Buses—State of the Practice. Washington, DC: The National Academies Press. doi: 10.17226/25061.
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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2018. Battery Electric Buses—State of the Practice. Washington, DC: The National Academies Press. doi: 10.17226/25061.
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1 Battery electric buses (BEBs), also known as all-electric buses, are attractive to transit agencies because they are cleaner, quieter, simpler, and smoother than their conventionally fueled counterparts due to their all-electric propulsion and auxiliary systems. These attri- butes result in zero tailpipe emissions (including zero local criteria air pollutants and carbon emissions), zero dependence on foreign oil, better experiences for passengers and drivers, and potentially lower operational costs. Because of the broad range of benefits and product availability within the market, transit agencies are purchasing BEBs on a much larger scale than in the past. However, there are still challenges associated with the technology, includ- ing range limitations, required charging times, high electricity rates for some locations, complicated utility rate structures, and higher capital costs. While some of these challenges are being addressed or mitigated through industry efforts and continuing improvements to the technology, there are still critical needs to be addressed in order for widespread deploy- ment and full commercialization of the technology. Executives of transit systems considering introduction of BEBs into their fleets and agen- cies wanting to improve or expand their BEB fleets should collect all of the information necessary to make educated decisions. This synthesis report will provide relevant informa- tion and considerations by reporting on the current state of a rapidly progressing technol- ogy. Through a literature review, a survey of 21 agencies with BEB experience (18 of 21 responded for an 86% rate) and five current case examples, this synthesis report represents a comprehensive analysis on the state of the practice for deploying BEBs, including planning, procurement, infrastructure installation, and operations and maintenance. The synthesis should also be valuable to another wide range of industry stakeholders including bus and component manufacturers trying to better meet the needs of their customers and federal, state, and local funding agencies and policy makers. As of the writing of this report, there are at least 13 BEB models available and more than 70 transit agencies with BEB deployments in the United States. In addition, there are almost 600 BEBs on order or in service. Half of the transit agencies reported they implemented BEBs due to a combination of board direction, environmental regulations, and environ- mental or sustainability programs, while a third of the agencies were doing it to test the buses in their service. As the number of BEB deployments has grown, so has the maturity level of the technology. Industry improvements include increased propulsion system reli- ability, increased battery energy capacity, and decreased capital costs of the BEBs. The benefits of BEBs have been reported in the literature. BEBs have demonstrated energy efficiencies of four times greater than diesel and compressed natural gas (CNG) buses through the Federal Transit Administration’s Altoona testing. While the buses have zero tailpipe emissions, studies show that even life cycle global warming emissions are almost S u m m a r y Battery Electric Buses— State of the Practice

2 Battery Electric Buses—State of the Practice 75% less than CNG and diesel buses. Further, BEBs produce significantly lower life cycle NOx emissions than diesel and CNG buses and lower life cycle particulate matter emissions than diesel and, in some energy production cases, CNG buses. The Altoona Bus testing also demonstrated reduced noise levels both inside and outside BEBs compared with conven- tional buses. Currently there are also many challenges for BEB deployments. Most of the agencies surveyed agree that decisions regarding the overall approach to BEBs and their supporting infrastructure should be carefully evaluated during the planning stage prior to deployment. For successful BEB deployments to occur, transit agencies must carefully plan how to inte- grate the technology in their specific operations and must undertake a strategic, coordinated approach to deploying both the buses and the appropriate charging infrastructure. These charging methods include plug-in charging, overhead conductive charging, and wireless charging. Transit agencies must not only determine which buses to purchase but also plan how, when, and where to charge their buses. These inter-related decisions depend upon a range of variables that are unique to individual agencies. Further, it is important for agen- cies to consider scale-up potential during initial planning as it is more economical to install certain infrastructure components (e.g., conduit, wiring, and transformers) at once rather than continually upgrade them as the fleet grows. Another challenge is the lack of technology support tools and practices to assist with BEB procurement and planning activities. Only half of the agencies surveyed stated that they factored electricity rates and/or demand charges into their decision to purchase BEBs and about half of respondents did a life cycle cost analysis during the procurement. More than half of the transit agencies used their own agency experience in combination with bus manufacturer predictions and bus trials to evaluate vehicle range, select suitable routes, and determine the type of charging method best suited for their agency. Advanced modeling and simulation techniques that help to predict some of the operational issues that have been reported were used by a third of the agencies. The majority of transit agencies responded that such tools and services would be beneficial when making decisions regarding range predictions, utility rate analysis, and life cycle cost analyses and adjustments. While the cost for BEBs has always been considered a challenge and capital costs are still approximately 40% to 50% higher than diesel and CNG buses, they are dropping significantly with economies of scale and technology improvements. The technology improvements are most pronounced for the traction batteries. The availability of federal, state, and local fund- ing incentives also help offset the incremental capital costs of BEBs and the new charging infrastructure. Early indications from maintenance cost data point to lower costs than con- ventional buses due to the relative simplicity of the buses and the lower number of bus parts. Operating costs for BEBs can also be lower than conventional buses due to the efficiency gains and the potential for cheaper energy costs. However, these costs (and the total cost of ownership) are heavily dependent on utility rates. Despite an almost four times improve- ment in fuel economy for the buses, energy costs were higher for BEBs than for CNG buses as reported by a National Renewable Energy Laboratory (NREL) study and some of the agencies responding to the survey conducted as part of this synthesis. Transit agencies with experience deploying BEBs noted that recurrent BEB driver train- ing is critical for project success and lowering operating costs. First, driving habits can significantly affect BEB efficiency and performance and on-route charging adds a new, un- familiar requirement for drivers. Second, agencies reported more efficient deployments when they coordinate early in the process with a wide group of stakeholders including com- munity leaders, public groups, and unions in order to avoid issues after deployment.

Summary 3 In general, notwithstanding all the previous challenges, the transit agencies reported that BEB operations went smoothly, the buses worked well, and there were minimal problems. Availability and reliability of BEBs is reportedly approaching that of conventional vehicles. And reliability of charge infrastructure is reported to be excellent. In fact, when asked to rank their overall satisfaction with BEB deployments on a scale of 1 to 10, 12 of the 13 agen- cies responded positively by ranking satisfaction at 5 or above and 8 of those agencies pro- vided a very high ranking of 9 or 10. Eighty-six percent of the responding agencies plan on purchasing more BEBs. One agency is fully electric, and three other agencies responded that they intend to be fully electric by years 2018, 2025, and 2030, respectively. This synthesis report identifies some gaps in knowledge and challenges to implemen- tation that should be addressed with both further research and actions. In order to see large, full fleet conversions, there is a need to document successful responses to challenges associated with deploying charging infrastructure at scale. Challenges include land use, space constraints, grid demand impacts, fleet staging for charging, labor requirements for making manual connections and maintaining charging equipment, and maintaining operability during power outages. These challenges affect almost all stakeholders, and the industry needs to continue to work together to find solutions. Given that BEB operating costs are heavily dependent on utility rates, understanding the rates, their variability, their effect on the business case, and the optimization of rate struc- tures for BEBs is another significant need for the industry. Agencies reported that more experience and data are needed to be able to fully evaluate and understand actual life cycle costs associated with BEB deployment. Further, life cycle cost assessment methods should be developed and utilized in the procurement phase. To ensure interoperability, charge standards must be developed for all forms of BEB charging. Procurement guidelines for BEBs and charging infrastructure likewise need to be established similar to those that are available for conventional buses. Transit agencies, bus manufacturers, component suppliers, industry nonprofits, and transit associations are participating in working groups that are actively addressing these issues. In summary, the benefits of deploying BEBs can be extensive. BEBs are matching reli- ability of conventional buses, and battery technology continues to advance at a rapid pace driving down costs and offering increased range capabilities. However, capital costs must continue to be reduced to be on par with diesel and CNG technologies. Utility costs, par- ticularly demand charges, need to be better understood and structured to be affordable, especially in comparison to diesel and CNG costs. BEB fleet scale-up concerns must be addressed both from an industry perspective and within individual fleets. Finally, technical support and advanced tools need to be utilized for making objective BEB procurement and planning decisions specific to the individual needs of the transit agency. If done correctly, transit agencies can, and are, realizing benefits ranging from lower total cost of ownership, reduction of environmental impact, performance improvements, and improved customer experience.

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TRB's Transit Cooperative Research Program (TCRP) Synthesis 130: Battery Electric Buses—State of the Practice documents current practices of transit systems in the planning, procurement, infrastructure installation, operation, and maintenance of battery electric buses (BEBs). The synthesis is intended for transit agencies that are interested in understanding the potential benefits and challenges associated with the introduction and operation of battery electric buses. The synthesis will also be valuable to manufacturers trying to better meet the needs of their customers and to federal, state, and local funding agencies and policy makers.

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