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33 PHASE 2 TECHNOLOGY SELECTION AND SPECIFICATIONS 2.1 Overview Your ZEB technology selection should be based on assumed performance on your routes, under your service constraints. The efficiency and range of ZEBs can vary significantly between different bus models and types of routes. Temperatures also affect ZEB performance, as heating, ventilation, and air conditioning (HVAC) systems can consume significant energy, lowering overall efficiencies. Your transit agency can evaluate bus performance in advance of ZEB deployments through modeling and route simulation, operating a test bus, or analyzing data from other ZEB deployments. Some method of bus modeling or data analysis is critical for understanding expected bus performance and informing charging schedule requirements for BEBs. Your bus and infrastructure requests for proposal (RFPs) should specify the technical and performance requirements that satisfy your service needs within the constraints of your operating conditions. Utilize the knowledge of your service area, transit agency operational requirements, and results of modeling efforts to identify your specification essentials. Consider both technical and performance specifications to ensure delivered buses and fueling infrastructure perform as needed. Ensure procurement documents also provide for desired inspection and acceptance testing plans as well as any warranty requirements. Pay close attention to specifications sections unique to ZEBs, including: ⢠Service requirements, ⢠Bus charging or hydrogen fueling requirements, ⢠High-voltage or hydrogen safety, and ⢠Battery warranties and measurements of battery health. Best practices for technology selection and specifications include: ⢠Selecting suitable ZEB technology and deployment strategy based on bus performance evaluation using modeling and deployment data analysis. ⢠Developing clear technical specifications and performance requirements to ensure your buses and infrastructure meet your needs. ⢠Ensuring ZEB procurement documents include thorough and effective considerations for inspections, acceptance testing, and warranties.
34 Guidebook for Deploying Zero-Emission Transit Buses 2.2 Key Stakeholder Considerations Project Managers ⢠Base technology selection on modeling results and specific transit agency requirements, as bus performance can vary greatly based on temperature, topography, and driving habits. ⢠Ensure route modeling efforts do not simply rely on OEM-provided range or energy efficiency estimates as those are typically based on ideal operating conditions and may not reflect your transit service demands. If BEB technology is selected, consider charge and utility rate modeling to identify your constraints for charging windows, suitable blocks or routes, flexibility in planning for equipment, and costs. ⢠Coordinate with your operations and maintenance staff to develop clear technical and performance specifications for your bus and fueling infrastructure. ⢠Ensure all expectations are clearly defined in your procurement documents and final contracts. Operations, Maintenance, and Facilities ⢠Participate in route modeling discussions, as schedule accommodations may be required due to range limitations for BEBs. ⢠Based on expected battery warranty conditions, evaluate how battery degradation may impact service planning over the life of the bus. ⢠Operation and maintenance of the bus will affect performance. Ensure adequate training requirements are included in contracts. Procurement ⢠Determine the best type of procurement approach for your bus and infrastructure selections [e.g., invitation for bid (IFB), request for proposal (RFP), request for information (RFI)]. ⢠Coordinate with the Project Manager, Operations, and Maintenance to ensure procurement documents include the required technical and performance specifications without unintentionally creating vendor bias. ⢠Ensure final contracts include the same specifications, as well as your inspection plan, acceptance testing requirements, and adequate time for testing. ⢠Consult APTA guidelines for ZEB procurements to understand existing industry standards. External Stakeholders ⢠Selected OEM(s) should be engaged quickly to finalize clear contractual specifications and requirements. Be sure all expectations are defined, measurable, and understood by all parties.
Technology Selection and Specifications 35 2.3 Bus Performance Evaluation Comprehensive analysis that evaluates potential bus performance under a range of conditions is one of the only ways to predict success of your deployment in your service area. Transit agencies have used the following approaches to evaluate bus performance in advance of ZEB deployments: ⢠Bus modeling and route simulation, ⢠Evaluating data from a test bus demonstration by an OEM or nearby transit agency, and ⢠Analyzing data from other ZEB deployments. Regardless of the approach taken, it is critical to evaluate bus performance under all conditions expected in your service throughout the life of the bus. Climate, bus specifications, and route conditions are only a few of the variables that can impact ZEB efficiency. Understanding the impacts of these variables on energy efficiency will ensure that you select the technology that will meet your expectations and provide the most value. Bus modeling and route simulation is a cost-effective method to assess the operational requirements of your ZEB fleet. A suggested approach for modeling is described in the next section. 2.3.1 Bus Modeling and Simulation Considerations Modeling and simulation provide the most valuable estimates of range and energy consumption and, as results, are specific to the unique conditions of your transit service. Route modeling helps alleviate ârange anxietyâ by providing confidence that a bus meets expectations for range and performance. Vehicle range and energy consumption estimates allow you to identify feasible blocks for your ZEB technology and inform charging schedule requirements for BEBs. Most OEMs provide mileage range estimates that are based on Altoona testing conditions, which may not reflect actual transit service in your service area (See Appendix B). OEMs may also offer route modeling services, but you should evaluate the model assumptions and results carefully to ensure your service area is accurately represented. While modeling will provide a more accurate assessment of range than Altoona test results, use caution when trying to predict a mileage range for your bus. The total miles possible on a certain day will vary based on many factors that affect efficiency, including: ⢠Route conditions. Speed, stop and go requirements, door openings, traffic conditions, and gradeability. ⢠Passenger loading. The total weight of the bus.
36 Guidebook for Deploying Zero-Emission Transit Buses ⢠Ambient air temperature. Heating and cooling energy required to maintain passenger comfort. The impact of HVAC system usage on energy efficiency is more significant for BEBs than for FCEBs, since FCEBs can utilize waste heat to heat the cabin. ⢠Driving style. CTE has observed more than 25% differences in energy efficiency based on driver performance and driving style (e.g., braking and acceleration techniques). ⢠Battery state of health. The usable battery capacity remaining for the bus. 2.3.2 Bus Modeling and Route Simulation Approach A modeling and simulation tool that accommodates varying powertrain configurations and components will provide the most flexibility for service simulations. The added capability of modeling fueling configurations will help further define refueling windows and provide service parameters. Regardless of the tools used, ensure the analysis utilizes your specific bus specification, your route information, and your load profiles. The Argonne System Modeling and Control Groupâs freely available application, Autonomie, can be used to perform powertrain modeling and simulation. By supplying different duty cycles, powertrain configurations, and bus components, Autonomie can run a simulated operation of a bus on route to determine how the bus will perform in any given situation. Steps for successful modeling and simulation include: 1. Complete an initial block screening. Categorize your blocks with an initial assessment of estimated energy requirements, considering both mileage and time, to understand the impacts of drivetrain and auxiliary system energy: o Are some blocks not possible for a BEB on a single charge due to their duration? o What are the shorter blocks that can easily be completed by a BEB? o Which blocks are you uncertain about? Figure 2-1 shows an example of a block screening approach to identify blocks that are likely satisfied, possibly satisfied, or unfeasible for the modeled ZEB. The "Possibly" blocks are a good focus for further modeling or analysis. Long-range buses have battery packs that weigh up to 6,500 pounds. Gross vehicle and axle weight rating limitations may reduce passenger capacity. State regulations and local codes for curb weight may apply as well. Conduct analysis on desired capacity and weight constraints before committing to a long-range or quick-charge bus strategy.
Technology Selection and Specifications 37 2. Collect data from route(s) that are representative of your service area. Current route data will be inputs to your model. Collecting data for the full block duration over multiple days will help reduce sampling bias and understand the influences of traffic for a single route. Identifying routes that are representative of the conditions throughout your service area will allow you to apply the results broadly without having to collect data from and model each route individually. 3. Model "nominal" and "strenuous" vehicle efficiencies. It is not feasible to evaluate the bus capabilities under every combination of variables that affect bus efficiency and range. Define "nominal" and "strenuous" energy profiles to determine upper and lower bounds for possible energy usage in your service area. The "nominal" efficiency is intended to represent an average day. The "strenuous" efficiency is intended to represent a hard day for a ZEB that is reasonably likely to occur. This efficiency is not intended to represent the worst-case scenario. Figure 2-1. Block screening example for routes that are likely, unfeasible, and possibly able to be completed by ZEBs.
38 Guidebook for Deploying Zero-Emission Transit Buses Varying road conditions, traffic, HVAC usage, highway driving, and hill climbs will drive routes toward either a nominal or strenuous condition. The following parameters may help define a "strenuous" efficiency: ⢠Vehicle weight: At or close to the gross vehicle weight rating (GVWR). ⢠Climate conditions: Average temperature of a "worst case" month (averaging over a period of 10 years), which will be either in the summer or winter, depending on your location. Incorporate any relevant climate conditions often experienced in that month. ⢠Route conditions: Identify a challenging speed profile and grade profile in your service area, such as a high-speed route, or a slower-speed route with heavy HVAC loads or long idling windows. Model conditions over a sample of routes that are representative of your service area and then propagate the efficiencies over similar routes, as needed. Break out energy requirements for motive and auxiliary loads. Treating time and distance separately allows you to more easily account for changes in planned service, if a bus is out for longer than expected. Depending on your service goals (e.g., 100% ZEB route or fleet), you may want to define your strenuous efficiency using more severe conditions to ensure that your selected technology will always be able to meet your needs. Alternatively, consider developing decision-support tools that help dispatch understand the expected range based on daily conditions. You will likely experience days that are more and less energy efficient than the nominal and strenuous conditions. These days are not representative of typical service, and may not be useful planning tools. Planning for the âworst caseâ day may not be feasible or practical; however, the results of a "worst case" simulation can be instructive and can inform the limitations of ZEB performance.
Technology Selection and Specifications 39 4. Model impacts from battery degradation. In addition to nominal and strenuous duty cycles, it is important to understand what impact battery degradation will have on your ZEB capabilities. As the âusableâ energy from your bus decreases, so will the available range. Figure 2-2 provides an example comparison of the available energy remaining to complete a specific block with a new and old BEB battery. Battery degradation will likely be the most significant in long -range BEBs, where higher depths of discharge are seen on a regular basis. On-route charged BEBs and FCEBs typically maintain battery state of charge (SOC) in a narrower range. Most OEM battery warranties will replace batteries when they are at 70%â80% of their initial capacity. Understand what service needs your ZEB can satisfy when the batteries are approaching warranty limits. This will be necessary to ensure full use of your buses throughout all stages of battery health. 5. Incorporate BEB charging. With transit agencies recognizing the cost of power at scale, it is becoming increasingly important to optimize BEB charging scenarios that minimize costs while meeting service needs. Based on your initial deployment plans, incorporate depot charging, on- route charging, or both in your models. Account for any factors that may affect charger performance or charge rates, such as power or current limitations, battery cooling system or cell limitations, as well as impacts from misaligned charge connections. Transit agencies planning for tight charge windows need to make sure charge times are achievable and realistic. For depot-charged BEBs, energy is often required to precondition the batteries and cabin prior to operation, which can reduce the effective charge rate. If your charger isnât able to charge at the expected rate, charge times will increase, putting Figure 2-2. Example usable energy for a new and old BEB battery.
40 Guidebook for Deploying Zero-Emission Transit Buses schedule adherence or route completion at risk. For on-route charging scenarios make sure to account not just for charge time, but also for time to dock to the charger and disengage from the charger. 6. Apply results. A common adage is "all models are wrong, but some are useful." Use the modeling results as an educational tool to get an understanding of energy requirements and the relative differences between seasonal behavior and expected performance. Based on modeling results, determine any needed changes to operational schedules, such as charging layovers, route adjustments, or preconditioning before pullout. High heating or cooling requirements can also impact the range of a BEB. Identify if seasonal adjustments must be made to the ZEB deployment plan to accommodate longer charge times or shorter blocks. 7. Validate and update model. Once you receive your ZEBs, conduct validation testing and use real-world data to update model assumptions and parameters, making the model more accurate for future deployments. 2.4 Technology Selection Use the results of modeling efforts and the evaluation of your service needs to select the desired technology and fueling approach (i.e., charging strategy or hydrogen fueling approach) for your deployment. To supplement modeling results, some transit agencies choose to release an RFI about available ZEB models, propulsion technology, battery chemistry, business models, and proposed solutions for charging and service needs. This approach will add time to your procurement schedule, but it may be particularly helpful if your transit agency is unfamiliar with the available bus technology. The information you learn from the RFI will help you understand the limitations and possible applications of available technology. Deployments in Action A transit agency utilized an overhead fast charger and found that recharge times were unexpectedly longer on very hot days. Our analysis helped identify that the charger/battery management system was limiting charge rate to prevent battery damage from overheating . Deployments in Action A transit agency in a very cold climate found that snowy or icy conditions impacted traction and reduced regenerative braking, lowering the total range of the bus. Plan for potential for reduced range when designing winter service plans.
Technology Selection and Specifications 41 2.5 Procurement Considerations Some states have FTA-compliant bus procurement contracts that include ZEBs. Procuring ZEBs from an existing state contract can save time and money; however, developing technical specifications specific to your requirements is critical even with this approach. Some transit agencies choose to issue separate procurements for buses and fueling infrastructure. However, one RFP can be issued to procure both. The latter approach can streamline procurement and management efforts and may be beneficial for transit agencies looking for a turnkey solution for ZEB infrastructure, but may result in higher total costs and less flexibility in the chosen technology combination. If separate procurements are utilized, ensure that the project timelines are planned so that the fueling infrastructure is installed and commissioned prior to the buses being delivered. In all solicitations, ensure adherence to internal procurement guidelines and avoid specifications that create unintentional vendor bias. The following sections provide information on key components of an RFP that will inform your final contract specifications. 2.5.1 Technical Specifications Thorough and detailed technical specifications are one of the best ways to mitigate risks of receiving buses and fueling infrastructure that do not meet your expectations. If your transit agency does not have significant internal expertise on ZEBs, outside experts are recommended for drafting comprehensive specifications for both your bus and fueling infrastructure. At a minimum, your bus and fueling infrastructure specifications should require that: ⢠The delivered good shall adhere to all applicable federal, state, and local regulations, codes, ordinances, or guidance, including Altoona testing, Buy America regulations, and ADA requirements, among others (e.g., it must operate legally) . ⢠The delivered good shall be able to effectively operate in the intended local environment (including topography, climate, etc.) and in accordance with contract specifications (including any bus-charger interoperability requirements). ⢠The delivered good shall be manufactured in accordance with sound industry standards and in compliance with relevant codes and standards, which may include but are not limited to high-voltage components and wiring, hydrogen fuel storage and supply, electromagnetic radiation, and fire safety and suppression. ⢠In the absence of a specification, the OEM will adhere to internal manufacturing standards and quality controls. Once you are confident in your selected technology, you will issue a procurement to purchase the buses and associated infrastructure.
42 Guidebook for Deploying Zero-Emission Transit Buses The sections below provide additional guidance for developing technical specifications for the bus and fueling infrastructure. As an emerging industry, standardized, well-vetted procurement guidelines for ZEBs do not yet exist. Recognizing this, APTA established an industry work group to develop BEB-specific procurement guidelines (Figure 2-3). These new guidelines are expected to be available in 2020. Sharing many characteristics and components, these guidelines can be used as a starting point for FCEB specifications. Consulting other transit agencies that have deployed ZEBs or reviewing publicly available ZEB procurement documents can provide useful guidance on common considerations for your specifications. Your final bus specifications should include the details necessary to ensure your ZEB will perform as needed throughout its useful life. The following topics are unique to ZEBs and should be considered when developing your specification: 1. High-voltage systems and components. BEBs and FCEBs contain high-voltage systems that require adherence to industry standards and supplier guidelines for safe operation, including, but not limited to, ground-fault detection systems, interlock circuits, DC and AC isolation detection systems, and placards for high-voltage panels. Your specifications should also require certification that subcomponents were installed in accordance with those standards and with supplier guidelines for installation and integration. 2. Electromagnetic interference. Electromagnetic interference (EMI), also known as radio-frequency interference (RFI) is another factor unique to ZEB procurements. Your bus specifications should require that your bus meets applicable electromagnetic compatibility (EMC) standards to prevent performance degradation and interference with other systems. 3. High-voltage wiring. In addition to the bus components, following industry protocols and standards for high- voltage wiring should also be part of your ZEB specification. Improper wiring practices can increase the risk of EMI and fire hazards. Figure 2-3. Cover of Draft APTA Bus Procurement Guidelines. (Image Source: APTA)
Technology Selection and Specifications 43 4. Fire safety and hydrogen gas detection. While fire hazards are not unique to ZEBs, there are factors that make them more challenging. Hydrogen fires are invisible; battery thermal ârunaway eventsâ pose both physical and health hazards and require unique suppression strategies. Understand the safety hazards associated with your ZEB technology and require any leak or thermal detection systems and fire suppression systems should, at a minimum, satisfy applicable fire safety industry standards and codes. 5. Operations, maintenance, and safety training. Your ZEB specifications should provide contractual support for your operating and maintenance training needs (see Phase 7: Personnel Training and Development). It should also require OEM training of first responders, as they are best positioned to provide details on high-voltage component locations and designed suppression characteristics. 6. Design operating profile. The design operating profile will indicate what your requirements are for the buses in service. This will drive the size of the energy storage system for BEBs or the fuel cell/battery configuration for FCEBs. The operating profile should be as detailed as possible and should describe the required performance throughout the entire service life of the bus as BEB battery capacity or FCEB fuel cell power output degrades over time. ⢠If you have a specific block or route in mind for your ZEBs, describe the daily service requirements that must be met by the bus, including mileage between charging or refueling, time, average speed, maximum speed, gradeability, and passenger load. You may choose to provide GPS data of the route to potential vendors. ⢠If you do not have a specific block or route in mind for your ZEBs, indicate a mileage requirement between charging or refueling, and describe what duty cycle the bus will operate on, based on the conditions in your service area. ⢠Describe the climate conditions that the buses will be operating in to inform auxiliary system usage and charging requirements as heating and cooling may use significant energy. Industry Standards and Codes With emerging technologies, industry standards are continuously evolving and should be researched prior to each ZEB deployment. Appendix C provides a list of industry standards that have been used in previous FCEB and BEB specifications. However, it is not intended to be a comprehensive list of all applicable standards.
44 Guidebook for Deploying Zero-Emission Transit Buses Require that the bus must be able to complete the operating profile described in the specifications for the entire service life of the bus. 7. Data monitoring and data availability. Data availability and monitoring allows thorough evaluation of your ZEB fleetâs performance and ensures access to necessary data to diagnose and troubleshoot bus issues. ZEB performance analysis requires greater visibility into bus performance data and system loads. Your specifications should describe your transit agencyâs desired data monitoring capabilities, any required interoperability between bus data monitoring systems and your transit agencyâs existing data monitoring systems (e.g., TransitMaster, FLEETWATCH, Clever Devices), and access to the necessary data. You should also request information on all available options for data monitoring that the OEM offers, including third-party service providers. 8. Fueling infrastructure compatibility. Suggested specifications for fueling infrastructure are listed in the sections below, but you must ensure that your bus is compatible with the charging or hydrogen fueling infrastructure that you are procuring. For BEBs, specify the location of charging ports or interface with charger, AC or DC charging, and charging standard compliance (e.g., SAE J1772, SAE J3068, SAE J3105, SAE J2954/2). For FCEBs, specify the fueling nozzle receptacle (i.e., TN1 or TN5). Mileage requirements While defining a minimum operating range for your buses is beneficial to ensure your vehicles will be able to complete useful work throughout their service lives, take care to include more information than just a mileage range requirement, as these can be hard to satisfy or disprove. Ensure you have properly detailed the conditions for which range must be met. Does that condition only apply to new batteries? Or is it intended to be a requirement for the entire service life of the bus? Must the range be met under normal transit service, with HVAC and other accessories running? Or does the range requirement align with duty cycles associated with Altoona testing requirements? A robust range requirement will be based on battery energy in the âallowableâ or recommended range of %SOC that can be used in regular transit service and will require that acceleration and gradeability needs be met with HVAC and other auxiliary systems on.
Technology Selection and Specifications 45 The sections below outline areas of focus for charging and hydrogen fueling infrastructure technical specifications. The specifications may vary based on the services that are being procured (e.g., design, construction). Specifications should be clear that adherence to federal, state, and local regulations, codes, standards, and guidance is the responsibility of the contractor. BEB charging infrastructure specifications will be informed by your selected bus technology, selected location, and available electrical infrastructure. Considerations for a depot charging scenario using plug-in chargers and on- route charging scenarios using overhead or inductive chargers are included below. However, the bus and charger combination you deploy may use any combination of charging capabilities. 1. Charger type. Specify whether you are procuring plug-in, overhead conductive, or inductive chargers. For plug-in and overhead chargers, specify the dispenser type. Plug-in Chargers Plug-in chargers can provide AC or DC power. Require plug-in chargers to be in compliance with Society of Automotive Engineers (SAE)-approved charging standards, SAE J1772 for DC chargers or SAE J3068 for AC chargers. On-route Chargers For overhead chargers, indicate whether you will be using a pantograph, inverted pantograph, or pin and socket dispenser. Overhead chargers should support SAE J3105, and inductive chargers should support SAE J2954/2 ( as of 2019, a work in progress). 2. Charging rate. For any charger type, specify the required power output per charger or fully describe the requirements of the charging window. Specify that this requirement should hold even when taking into account any cell balancing considerations. Depot Chargers For depot chargers, describe the amount of time available for the buses to fully recharge from the minimum recommended SOC, as well as any requirements for a midday charge. On-route Chargers For on-route chargers, describe the available time to charge per hour per bus (including time for the bus to dock and undock from the charger), the 2.5.1.2.1 BEB Charging Infrastructure 2.5.1.2 Fueling Infrastructure Specifications
46 Guidebook for Deploying Zero-Emission Transit Buses corresponding energy consumption of each trip when the bus is away from the charger, or describe the performance requirements of the charging equipment based on your planned service for all of the buses using the fast charge. On-route charging that utilizes overhead or inductive technology requires proper bus-charger alignment for optimal charging. If not properly aligned, actual charge rates may be significantly less than planned, increasing the time and cost of charging. Most technologies offer some driver assistance for alignment but would likely benefit from extra visual cues or training to reduce misalignments. Require OEMs to explain suggested approaches for ensuring proper alignment, as well as expected actual charging rates if the bus is improperly aligned. 3. Charger configuration. Specify the number of chargers required, or describe your requirements (e.g., available charging window, peak power limitations, space limitations, available capital and operational funds) and have vendors propose a solution. Plug-in Chargers Some transit agencies prefer to have one lower-powered charger per bus for overnight charging. These chargers will have a lower per unit cost, but could result in higher energy costs if all chargers must charge simultaneously to meet service requirements. In this configuration, an additional charger may be beneficial for redundancy during charger maintenance events. Some plug-in charger models have multiple dispensers that can charge buses sequentially. As long as these models are of sufficient power to recharge all buses in the required time, this option can limit the overall peak power demand, lowering energy costs. These chargers tend to be of a higher power and have higher unit costs. If this is an option for your transit agency, include a requirement for details on sequential or simultaneous charging capabilities. Charging rates will vary based on the bus SOC. Generally, BEBs will charge more slowly (i.e., at lower power) at a higher SOC, with charge rates significantly slowing down above 90% to 95% SOC, depending on the OEM. For on-route charged buses, this may result in a smaller gain of SOC during the charging window than estimated. Request that the OEMs include a chart indicating allowable charge rates into the bus (kW) at varying SOC (0% to 100%, in increments of at least 10%). Some charger OEMs limit power across the operating profile, or with output voltage. Require that OEMs provide a map of how power may vary in these situations.
Technology Selection and Specifications 47 Regardless of the preferred configuration, specify the location for the charger port(s) for plug-in chargers (i.e., front or rear, curbside or streetside) and the port height. Describe any cable management requirements. On-route Chargers Fully describe your requirements for simultaneously charging multiple buses with on-route charging systems at the same location, as SAE J3105 (work in progress) requires a certain distance between overhead charging dispensers. 4. Charger location. Indicate the planned locations of charging equipment. Include annotated building schematics or diagrams that show available locations for equipment, the location of electrical utility tie-ins, and available locations for equipment staging, if the contractor will be responsible for any construction services. For on-route chargers, describe the property rights at the charger location, and any coordination that must occur with external stakeholders to install equipment. Indicate any security or safety enclosures that will be required. 5. Charger/demand management & backup systems. High-powered on-route chargers can require significant power throughout the day. Overnight, simultaneous use of plug-in depot chargers can also require significant power. Time-of-use utility rates (See Phase 4: Fueling Infrastructure Strategy and Cost) and demand charges can make recharging your bus at certain times of the day more costly. In addition, short power outages can quickly lead to service disruptions. Your on-route charger specifications should also consider any charge management capabilities, demand management capabilities, or energy storage systems your transit agency desires for energy cost or service stability (See Phase 8: Operation and Maintenance). 6. Power distribution requirements. Describe the current available power and distribution assets (e.g., transformers, switchgear, metering) at the planned charge location, and any required upgrades. Coordinate with your electric utility to confirm the accuracy of the information included. 7. Data availability and monitoring. Similar to the bus specifications, indicate your data monitoring requirements from the charging system to support the evaluation of your ZEB fleet performance, as well as to diagnose and troubleshoot issues. Require the vendors to explain all available options for accessing charger data and fault codes. Describe any required interoperability
48 Guidebook for Deploying Zero-Emission Transit Buses between the charger data monitoring systems and your transit agencyâs existing data monitoring systems and access to the necessary data. 2.5.1.2.2 FCEB Hydrogen Fueling Infrastructure Detailed specifications for hydrogen fueling stations are complex and appropriately licensed third parties should be consulted for assistance. Installation of a fueling station will require a design and construction phase, potentially necessitating two separate RFPs. Your RFP specification should provide all known information related to project scope and constraints. It should also require a site visit and provide responders an opportunity for questions and clarifications, as the recommended design of the hydrogen fueling station will depend on the physical limitations of your site and the specific service needs of your fleet. Considerations for hydrogen fueling stations specifications are below. 1. Hydrogen storage needs and fueling requirements. Technical specifications for hydrogen fueling stations should detail your expected daily hydrogen consumption as well as any requirements for backup supply. Fuel consumption should be informed through careful modeling and discussions with the FCEB OEM. Fuel efficiency can vary depending on climate conditions, route topography, and passenger loadâprovide an average daily hydrogen consumption and a maximum daily hydrogen consumption, based on your service needs. You must also describe your available fueling window for your entire fleet of FCEBs and specifications for dispensing. Note the start and stop time when your staff is fueling vehicles back to back, including dwell time at the station. Estimate the number of vehicles fueled per hour of the fueling window. Hydrogen consumption and fueling requirements will impact equipment sizing, which will impact equipment costs. 2. Hydrogen production method. Indicate whether you will get hydrogen delivered to your facility or if you will generate it on site. For delivered hydrogen, determine if liquefied or gaseous best suits your needs. If you are generating the hydrogen on site, determine if electrolysis or natural gas reformation will be used. Identify any preferences for energy source (e.g., solar panels, combined heat and power applications, or electrical grid). Transit agencies that prefer to minimize or eliminate the carbon footprint of on-site hydrogen production are considering utilizing renewable energy to operate hydrogen production equipment, or reforming biogas. 3. Fueling station location. Indicate the planned locations of hydrogen fueling stations. Include annotated building schematics or diagrams that show available locations for equipment, the size and shape
Technology Selection and Specifications 49 of the site, the location of electrical utility tie -ins, and available locations for equipment staging. 4. Facility upgrades and safety. Make it clear which portions of the design, engineering, and construction services are included in the RFP and which portions are not included (See Phase 5: Fueling Infrastructure Deployment). FCEB deployments will likely require retrofits to garages (if buses are stored indoors) and maintenance facilities to accommodate safety standards and regulations for hydrogen storage and distribution. Indicate if the contractor will be responsible for the facility upgrades, such as replacing exhaust fans, modifying electrical systems, and implementing a gas detection system. Ensure that the selected contractor will address safety requirements associated with hydrogen fueling infrastructure. 2.5.2 Acceptance Criteria Specify the criteria for accepting bus and infrastructure technology to ensure that the technology meets all needed requirements. Ensure that you give yourself enough time to adequately test the buses and clearly state what criteria must be met and under what conditions to inform acceptance or non-acceptance of buses (See Section 6.5: Acceptance and Validation Testing). Some transit agencies structure acceptance periods as a specific period of continuous time (e.g., 40 hours) that the bus must operate in revenue service with no issues. With this approach, the clock will reset any time that an issue is discovered, and the acceptance period will extend until the conditions are met. Other transit agencies establish a testing period (e.g., 15 to 30 days) to test the bus in any way the transit agency sees fit. Some OEMs will not allow operation of buses in revenue service prior to acceptance, may have overly restrictive timeframes, or may not include provisions for delays in fueling infrastructure deployment. Review any acceptance terms carefully and address them in your acceptance testing plans accordingly. Ensure that you are clear in your procurement documents what criteria must be met for acceptance: All acceptance criteria should also be clearly communicated in final vehicle contracts. Ensure contract terms include adequate time for proper testing. Fueling infrastructure deployment and upgrades to maintenance facilities must be completed prior to bus acceptance for proper testing and validation of the buses. Ensure this requirement is listed in your RFP.
50 Guidebook for Deploying Zero-Emission Transit Buses ⢠Performance standards.Service demonstration criteria could require the OEM, upon bus delivery, to demonstrate performance standards based on the OEMâs modeling efforts . ⢠Extreme weather operation. Standards for component functionality or cabin temperature. ⢠System operability. Standards for uptime or requirements for all systems to function at time of acceptance. After completing post-delivery acceptance tests, APTA guidance suggests that transit agencies can offer the following certificates of acceptance (APTA, 2013): ⢠Accepted. ⢠Not accepted. In the event that the bus does not meet all requirements for acceptance, the agency must identify reasons for non-acceptance and work with the OEM to develop a timeline of addressing the problem for a satisfactory resolution and redelivery. ⢠Conditional acceptance. In the event that the bus does not meet all requirements for acceptance, the agency may conditionally accept the bus and place it into revenue service pending receipt of contractor-furnished materials and/or labor necessary to address the identified issue(s). Clearly specify requirements for component warranties in your RFP. Review any warranty information provided by OEMs to ensure that terms and conditions are understood and reasonable. Require respondents to include a comprehensive statement of any additional warranty terms relating to the battery or energy storage system (ESS), with explanations of all disclaimers that could affect your ability to make a warranty claim. Energy Storage System Warranty The usable capacity of ZEB batteries will degrade over time, which will impact vehicle range. This degradation is most significant in long-range BEBs that see a deeper discharge on a daily basis; however, fast-charge BEBs and FCEBs will also see some battery capacity degradation. Your technical specifications and contract documents should establish clear expectations for performance throughout the battery life, warranty terms, and replacement guidelines. Warranty conditions for batteries will vary by manufacturer, but warranties will usually specify a warrantable end of life (WEOL) capacity. The draft APTA BEB procurement guidance defines WEOL as a measure of battery degradation (usually a percentage of remaining battery capacity Figure 2-4. Summary of battery warranty duration. 2.5.3 Major Component Useful Life and Warranty Considerations
Technology Selection and Specifications 51 compared to the gross or nameplate capacity) determined as the point at which the batteries can no longer provide the energy or power required to meet the design operating profile. WEOL shall be used as a condition for battery replacement and to potentially initiate warranty claims (APTA, 2013). The following examples summarize ESS warranty terms offered by ZEB manufacturers (Figure 2-4): ⢠12 year, 500,000 miles to 70%â80% of nameplate capacity. ⢠6 year, with a specified kWh throughput, with an option to extend the warranty to 12 years, which would include a mid-life battery replacement. Request that respondents to your RFP identify any actions your transit agency might take that would negatively impact your ability to make warranty claims. Most OEMs will provide information on best practices for bus operation that will preserve battery life. Conditions that could negatively impact warranty terms include: ⢠Running the battery below the recommended SOC lower limit too many times; ⢠Storing the buses for prolonged period of times at very high or very low states of charge ; and ⢠Misuse or negligence, or if preventative maintenance activities have not been executed. Testing Battery State of Health Your RFP language should require respondents to specify the original energy storage capacity of batteries, the WEOL capacity, and acceptable methods to annually determine the usable battery capacity. Since this metric can be difficult to accurately measure, require OEMs to indicate how this test will be completed in their response , and whether the test can be performed by the OEM, a contracted third party, or the transit agency itself. Fuel Cell Warranty The maximum power output of a fuel cell may degrade over time. Warranty terms vary by fuel cell OEM, but recent examples include terms that allow 15% loss of maximum fuel cell power output over the 12 year life of a bus. 2.5.4 Documentation andTraining Documentation requests for ZEB procurements will generally be in line with your transit agencyâs requirements on past non-ZEB procurements. Ensure that copies of manuals for the following are required: ⢠Preventative maintenance, If the ESS is not warrantied through the entire useful life of your bus, evaluate the impacts to range with lower usable battery capacity, or consider the costs of a battery replacement. Consider requiring a not to exceed (NTE) cost for mid-life battery replacement. ⢠Diagnostic procedures,
52 Guidebook for Deploying Zero-Emission Transit Buses ⢠Spare parts, ⢠Final parts, ⢠Component repair, ⢠Operator instructions, ⢠Bus schematics, and ⢠Training materials. Ensure adequate OEM-provided operations, maintenance, and safety training is included in the contract. At least 80 hours of training is recommended, however your transit agency may need more depending on your familiarity with the technology. Subsequent deployments of the same or similar technology may require less training. While many OEMs have a standard training plan, most offer the option to purchase additional training hours, as needed (See Phase 7: Personnel Training and Development). 2.5.5 Contract Negotiation Ensure your bus procurement activities comply with all applicable federal, state, and local regulations related to ZEB deployments, including Altoona testing, ADA requirements, and Buy America requirements. The FTA Best Practices Procurement & Lessons Learned Manual (Figure 2-5) provides guidance for third-party procurements under FTA grant programs. State procurement guidelines should also be reviewed. There are several contractual terms and conditions that should be considered when negotiating your final bus contract to avoid misunderstandings, including but not limited to: ⢠Clearly defined technical specifications for your bus, identifying all previously negotiated approved equals; ⢠An inspection plan and inspection procedures driven by your technical specifications. (See Section 6.3: Vehicle Inspection); ⢠If the bus supplier is responsible for infrastructure, a requirement that fueling infrastructure be installed prior to bus delivery or acceptance, since acceptance should be measured utilizing your bus and fueling infrastructure; ⢠Measurable performance or acceptance criteria; ⢠Adequate time for bus testing and acceptance; and Figure 2-5. FTA's Best Practices Procurement & Lessons Learned Manual. (Image Source: FTA)
Technology Selection and Specifications 53 ⢠Appropriate plans for operations, maintenance, and safety training, with clear requirements for training hours, aids, materials, tools and diagnostic equipment. 2.6 Additional Resources ⢠Alternative Fuel Safety, National Highway Traffic Safety Administration ⢠Autonomie, Argonne National Laboratory, U.S. Department of Energy ⢠Best Practices in Hydrogen Fueling and Maintenance Facilities for Transit Agencies, CALSTART ⢠Best Practices Procurement and Lessons Learned Manual, Federal Transit Administration ⢠Standard Bus Procurement Request for Proposal, American Public Transportation Association ⢠State Electricity Profiles, Energy Information Administration
