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40 Full Fleet Characteristics As part of this synthesis report, a survey was developed to capture the current state of the practice for transit agencies deploying BEBs. This extensive survey, provided in Appendix A, captured the many aspects and considerations related to deploying this technology, which is new to many agencies. The survey results are split up into three chapters. This chapter describes the agency characteristics for the 21 agencies selected and surveyed out of approxi- mately 72 agencies that are currently in the process of procuring BEBs. Chapter 4 addresses the planning considerations for procuring and deploying BEBs. Chapter 5 collects informa- tion on in-service experience from the operation of BEBs. Full survey details can be found in Appendix B. The survey had an 86% response rate, with 18 out of the 21 respondents submitting informa- tion. Not all respondents answered every question either because they chose not to answer or because the question was not applicable to them. Therefore, the following results are provided in terms of how many agencies answered the particular question, in which case the number of respondents is indicated by ân = â. The transit agencies surveyed ranged in size, location, and experience with BEBs. The transit agencies that responded were distributed throughout the United States, as depicted in Figure 17. BEB Fleet Characteristics The survey accounted for 163 BEBs either delivered or on order (not including options to purchase BEBs) at the time the survey was conducted, which was February 2017. A summary of the agenciesâ characteristics is shown in Tables 6 and 7 and Figure 18. BEB fleet composition for the respondents ranged from 0.1% to 100%. Most of the agencies reported BEB fleets that are between 1% and 10% of their total fleet size, with a minimum of two, an average of six, and a maximum of 18 buses deployed during peak periods. Fifteen of the agencies currently operate the BEBs while the other three agencies are planning for them, that is, either they have buses on order or they have received the buses but have not deployed them in service yet. One responding transit agency has operated BEBs since January 1991 (more than 3 million miles), but most of the responding transit agencies have operated BEBs anywhere from 12 to 40 months. The size of the BEB traction battery is an important specification for BEBs because it iden- tifies the amount of energy a bus can store on board and is indicative of the range between recharges. It is also a component that bus OEMs carefully size because it has an effect on many factors, including bus weight, cost, range, and charge strategy. The reported size of the trac- tion batteries generally fell into three size categories. Seven agencies use buses with traction batteries that are between 72 to 105 kWh, one agency uses buses with a 200 kWh battery, and C h a p t e r 3 Survey Results and Agency Characteristics
Survey results and agency Characteristics 41 Figure 17. Map of agencies that responded to the survey. Blue stars indicate agencies that responded to the survey. Red stars indicate agencies that responded to the survey and were also selected to participate in the case examples. Source: Center for Transportation and the Environment. Transit Agency # Total BEBs Total Buses Percent of BEBs 1 3 113 3 2 1 1583 0.10 3 30 370 8 4 2 75 3 5 2 68 3 6 34 163 21 7 16 31 52 8 15 304 5 9 6 66 9 10 6 53 11 11 3 1474 0.20 12 5 681 0.70 13 2 1870 0.10 14 9 274 3.30 15 4 185 2 16 6 6 100 17 14 105 13 18 5 64 8 Fleet Information Source: Center for Transportation and the Environment. Table 6. Fleet information of the agencies surveyed (n = 18).
Transit Agency # 35 40 60 Cutaway Other Total 1 - 3 - - - 3 2 - 1 - - - 1 3 15 15 - - - 30 4 - 2 - - - 2 5 - 2 - - - 2 6 - 21 13 - - 34 7 5 1 - - 10 16 8 9 6 - - - 15 9 - 6 - - - 6 10 5 1 - - - 6 11 - 3 - - - 3 12 - 5 - - - 5 13 - 2 - - - 2 14 9 - - - - 9 15 - - - - 4 4 16 5 1 - - - 6 17 - - - - 14 14 18 - - - - 5 5 Total 48 69 13 0 33 163 BEB Fleet Size Distribution Source: Center for Transportation and the Environment. Table 7. BEB fleet size distribution for the agencies surveyed (n = 18).
Survey results and agency Characteristics 43 seven agencies use buses with traction batteries between 300 to 325 kWh. As expected, BEBs with the larger batteries were typically used in a depot charge configuration, while on-route charged BEBs were able to use smaller battery packs, as shown in Figure 19. However, agen- cies also combined large battery buses with on-route charging (both overhead conductive and wireless) in two cases. Charging Characteristics While all 18 agencies utilize depot (or shop) charging, half of the respondents also have on- route overhead conductive chargers. Additionally, two agencies utilize on-route inductive wire- less chargers, as shown in Table 8. The transit agencies reported they had anywhere from 3 hours to 10 hours available to charge at night (defined as reliable time parked in a stall to a plug-in charge), with 60% report- ing less than 5 hours available. Almost all BEBs on the market (including the longest range/ largest battery models) can fully charge with a plug-in charge in less than 5 hours. Three of the respondents stated that they operate on a pulse system, which can make on-route charging more difficult to implement since all buses are scheduled to depart from a transit center at the same time and layovers generally coincide with each other. When the lay- overs and hence available charge times for the buses overlap, it becomes difficult to coordinate charging and share chargers. In order to meet the extended range needs of certain fleets, agencies appeared to utilize on- route charging methods. For daily ranges of over 200 miles, on-route conductive and on-route wireless were utilized, as shown in Figure 20. Figure 21 provides a summary of how battery sizes and charge methods have been paired to address range needs of various routes. Large battery, depot charged, buses as well as small battery, on-route charged, buses were used to meet route lengths of less than 200 miles. On-route charging was used with any battery size configuration to meet longer daily range requirements. Currently operate battery electric buses in transit service. Have procured battery electric buses or have them on order, but have not received any of them. Have ordered and received some or all battery electric buses but have not put them into transit service. Figure 18. BEB deployment status of the transit agencies surveyed (n = 18). Source: Center for Transportation and the Environment.
44 Battery electric BusesâState of the practice 0 50 100 150 200 250 300 350 Ba tte ry S iz e ( kW h) Fleet Battery Size and Charging Strategy Depot Charging On-Route Conductive Charging On-Route Wireless Charging Figure 19. Fleet battery size and charging strategy (n = 15). Source: Center for Transportation and the Environment. Charger Type Number of Agencies with Charger Type Minimum Number of Chargers Used for BEB Fleet Average Number of Chargers Used for BEB Fleet Maximum Number of Chargers Used for BEB Fleet Bus-to- Charger Ratio* Depot Plug-in 17 1 4 22 1.5 On-Route Overhead Conductive 9 1 2 5 6 On-Route Inductive/Wireless 2 1 2 2 1 Depot Overhead 1 1 1 1 6 *Based on fleet with maximum number of chargers in each category. Source: Center for Transportation and the Environment. Table 8. Charging characteristics of the agencies surveyed.
Survey results and agency Characteristics 45 0 100 200 300 400 500 600 700 M ax im um D ai ly R an ge (m ile s) Maximum Daily Range and Charging Strategy Depot Charging On-Route Conductive Charging On-Route Wireless Charging Figure 20. Maximum daily range requirements and charging strategy (n = 10). Source: Center for Transportation and the Environment. 0 50 100 150 200 250 300 350 0 100 200 300 400 500 600 700 BE B Ba tte ry S iz e ( kW h) Maximum Daily Range (miles) Maximum Daily Range versus Battery Size and Charge Strategy Depot Charging On-Route Conductive Charging On-Route Wireless Charging Figure 21. Meeting daily range requirements (n = 10). Source: Center for Transportation and the Environment.