Guidebook for Deploying Zero-Emission Transit Buses (2021) / Chapter Skim
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From page 6... ...
6 ZEB TECHNOLOGY OVERVIEW A full ZEB fleet may include both BEBs and FCEBs, depending on the needs of your transit agency. Electric trolleys with overhead wires are also viable zero-emission technology but are not described further in this Guidebook.
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ZEB Technology Overview 7 CONSIDERATION BATTERY ELECTRIC BUS FUEL CELL ELECTRIC BUS • Costs will vary based on production method or delivery distance Fuel Cell Electric Bus and Hydrogen Fueling Infrastructure FCEB Technology FCEBs (Figure 2) utilize onboard hydrogen storage, a fuel cell system, and batteries.
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8 Guidebook for Deploying Zero-Emission Transit Buses supplier or produced on-site, (2) hydrogen storage tank(s)
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ZEB Technology Overview 9 Phase 5 Fueling Infrastructure Deployment provides more information on the design and deployment of hydrogen fueling infrastructure. A summary of hydrogen fueling station considerations is shown in Figure 5.
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10 Guidebook for Deploying Zero-Emission Transit Buses While the initial investment in a hydrogen fueling infrastructure may be significant, scaling up hydrogen fueling infrastructure may be less costly and less land-intensive than scaling up battery charging infrastructure. Some equipment expansion may be needed, but the total footprint of a hydrogen fueling station is similar to a diesel or CNG station.
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ZEB Technology Overview 11 APPROACH TYPICAL INSTALLATION ADVANTAGES DISADVANTAGES • Gaseous hydrogen must be stored in pressure vessels Produce hydrogen onsite through electrolysis • Electricity is used to convert water into hydrogen and oxygen. The hydrogen is captured and stored.
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12 Guidebook for Deploying Zero-Emission Transit Buses BEB and Charging Infrastructure Technology BEB Technology BEBs use onboard battery packs to power all bus systems. BEBs generally have no tailpipe emissions, however some transit agencies utilize an auxiliary fuel-fired heater to increase range in cold months.
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From page 13... ...
ZEB Technology Overview 13 Example Fast-Charge 40' BEB Characteristics • Battery capacity: 50–250 kWh • Reliable range in transit service: Indefinite range with periodic charging of sufficient duration • Capital costs: About $750K–$1M for base bus • Charging approach: 150–450+ kW overhead or wireless chargers, typically charged on-route BEB Charging Infrastructure Three options exist for BEB charging technology: plug-in charging, overhead conductive charging, and wireless inductive charging. Any of these types of chargers can be used to charge BEBs either at the depot or on-route.
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From page 14... ...
14 Guidebook for Deploying Zero-Emission Transit Buses or transit center locations and space, and utility rate schedules and costs. Transit agencies may choose a combination of chargers and charging approaches, utilizing both depot and on-route charging, to fully meet their needs.
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ZEB Technology Overview 15 As noted above, plug-in, overhead, and inductive chargers can be used either for depot charging or on-route charging. A summary of depot and on-route charging approaches is described in Table 4.
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16 Guidebook for Deploying Zero-Emission Transit Buses Table 4. Depot charging and on-route charging overview.
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ZEB Technology Overview 17 Plug-in Chargers Ground-mounted plug-in chargers (Figure 9) are a common choice for BEB charging, especially for overnight or midday depot charging.
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18 Guidebook for Deploying Zero-Emission Transit Buses Overhead Conductive Charging Overhead chargers are used for fastcharge scenarios. Overhead charging equipment typically uses a pantograph, where the moving parts are on the bus (Figure 10)
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From page 19... ...
ZEB Technology Overview 19 A risk of the inverted pantograph approach is that a malfunction of the charging station may have a significant impact on service, if the BEBs are unable to use the charger. Redundant equipment, or backup depot charging capabilities, can mitigate service risks.
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From page 20... ...
20 Guidebook for Deploying Zero-Emission Transit Buses flexible enough to allow a bus to miss at least one charge throughout the day due to improper alignment without impacting service. Figure 14.
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