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D-1 Appendix D Glossary Term Definition Acceptance Testing Procedure to identify defects that have become apparent between the time of equipment release and delivery to the transit agency, and to ensure that all contractual requirements for bus and charging or fueling infrastructure have been met. Air Balance Test Process by which the performance of HVAC airflow is measured. Once it is tested, the systems are then adjusted, or balanced, so that the air brought into a building is slightly greater than the air being pulled out of the building. Altoona Testing The Larson Transportation Institute's Bus Research and Testing Center, located in Altoona, Pennsylvania, was established in 1989 with funding provided by the Federal Transit Administration. The facility houses four bus maintenance and test bays and is fully equipped to perform heavy vehicle maintenance, repair, and testing as mandated under 49 CFR Part 665. The Center tests buses for safety, structural integrity, durability, performance, maintainability, noise, and fuel economy. In accordance with the 1991 Intermodal Surface Transportation Efficiency Act, the Center tests brake performance, bus emissions, and buses using alternative fuels. Autonomie Powertrain modeling and simulation software by Argonne System Modeling and Control Group that can run a simulated operation of a bus on route to determine how the bus will perform based on user-specified duty cycles, powertrain configurations, and bus components. Auxiliary Energy Energy consumed by time to operate all support systems.
D-2 Guidebook for Deploying Zero-Emission Transit Buses Term Definition Availability Measure of how often a bus was able to be put into service. The National Renewable Energy Laboratory (NREL) typically uses the following categories for availability: ⢠In-service (road calls should also be tracked on days when the bus is put into service) ⢠Event/Demonstration ⢠Not used ⢠Training ⢠Not available to be put into service Battery Electric Bus Zero-emission bus that uses onboard battery packs to power all bus systems. Battery Management System Monitors energy, as well as temperature, cell or module voltages, and total pack voltage and adjusts the control strategy algorithms to maintain the batteries at uniform state of charge and optimal temperatures. Battery Nameplate Capacity The maximum rated output of a battery under specific conditions designated by the manufacturer. Battery nameplate capacity is commonly expressed in kWh and is usually indicated on a nameplate physically attached to the battery. Block Refers to a vehicle schedule, the daily assignment for an individual bus. One or more runs can work a block. A driver schedule is known as a ârun.â Buy America Certification Provision requiring that in a transit project, federal tax dollars are used to purchase steel, iron, and manufactured goods that are produced domestically in the United States. Charge Depleting On-route charging approach for BEBs where the bus does not charge for sufficient time to completely recharge at least the energy that it consumed since its previous charging session. Daily depot charging is required for regular operation under a charge depleting scenario. Charge Management Optimization of charging processes to both meet service needs and minimize energy costs.
D-3 Term Definition Charge Modeling Recommended component of a BEB performance evaluation to understand the capabilities and limitations of charging scenarios. Charge modeling evaluates the effectiveness of planned charging windows, based on the specifications of the bus and charging equipment, as well as a transit agency's service plan and electricity rate schedule. Charge Sustaining On-route charging approach for BEBs where the bus charges for sufficient time to recharge the energy that it consumed since its previous charging session (or more). With a charge sustaining scenario, BEBs can operate indefinitely with no need for depot charging. Charging Equipment The equipment that encompasses all the components needed to convert, control and transfer electricity from the grid to the vehicle for the purpose of charging batteries. May include chargers, controllers, couplers, transformers, ventilation, etc. Charging Interface The equipment and/or coupler used to create a connection between the charging equipment and the vehicle for the purpose of recharging a vehicleâs batteries. Charging Station The location that houses the charging equipment connected to a utilityâs electric service to provide electricity to a vehicleâs battery system through a charging interface. Commissioning Process to verify if the equipment (i.e., charging stations for BEBs, hydrogen fueling station for FCEBs) functions according to design objectives and technical specifications. All charging or hydrogen fueling equipment must be commissioned to each bus. Configuration Audit Inspection activity to verify that the vehicle meets the contract requirements, reflecting any change orders, and to reveal any items requiring correction prior to first article inspection. Conventionally Fueled Vehicles A diesel, diesel hybrid, or CNG bus. Cryogenic Storage Required for the storage of liquid hydrogen since the boiling point of hydrogen at one atmosphere pressure is -252.8°C.
D-4 Guidebook for Deploying Zero-Emission Transit Buses Term Definition Curb Weight Weight of vehicle, including maximum fuel, oil and coolant; and all equipment required for operation and required in a technical specification, but without passengers or driver. Deadhead Operation Non-revenue time when a bus is not carrying passengers, usually a trip from, to, or between lines or garages. Usually this refers to the trip between the home division garage to the point where the bus enters or leaves its route. Demand Charges A charge by utilities that is often based on the highest kW demand used in a billing cycle over a window of time, typically 15- or 30- minutes. Depending on the rate structure, demand rates may also vary by the amount of power used and the time of day it is used. Demand charges are put in place to cover the cost of electrical infrastructure needed to meet the highest electricity demand at any time, since the electric util ity must always be able to meet the power demand for all of their customers at the instant that it is required. Depot Charging Centralized BEB charging at a transit agency's garage, maintenance facility, or transit center. With depot charging, BEBs are not limited to specific routes, but must be taken out of service to charge. Design Operating Profile Included in technical specifications, the operational requirements under standard operating conditions that the bus must be able to achieve. Dual-grid Operation Option to have your electrical power served by two installations of charging infrastructure across different portions of the power grid. Dual Power Feeds Providing two independent electricity paths to your charging infrastructure. Duty Cycle Information regarding how a vehicle is used, which includes (but is not limited to): hours per day; days per week; total miles; typical load profile; and peak load profile. Electricity Rate Schedule List of types and amounts of charges administered by electric utilities to customers. Rate schedules vary depending on customer type and geographic location.
D-5 Term Definition Electrolysis Method to produce hydrogen where electricity is used to split water into hydrogen and oxygen using an electrolyzer. Energy Quantity of work, measured in kWh for ZEBs. Energy Charges Electricity charge by a utility for the total energy consumption, which accrues throughout each month and is typically measured in kWh. Some utilities have seasonal rates, tiered rates for the amount of energy used, or higher energy charges for peak periods. Energy Efficiency Metric to evaluate the performance of ZEBs. Defined in kWh/mi for BEBs, mi/kg of hydrogen for FCEBs, or miles per diesel gallon equivalent for any bus type. Environmental Justice Fair treatment and meaningful involvement of all people, regardless of race, color, national origin, or income, with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies. Fair treatment means that no population bears a disproportionate share of negative environmental consequences resulting from industrial, municipal, and commercial operations or from the execution of federal, state, and local laws; regulations; and policies. Meaningful involvement requires effective access to decision makers for all, and the ability in all communities to make informed decisions and take positive actions to produce environmental justice for themselves. First Article Inspection Conducted when the build of the first bus is complete and all issues from the configuration audit are addressed. When complete, the first article inspection provides a verified compliant configuration so that a notice to proceed (NTP) can be issued for the rest of the bus order. Fixed Costs Recurring monthly service fee on an electricity bill, often used to cover the price of being connected to the electric grid. Fleet Transition Plan Plan that outlines the timeline and preferred technology to replace a fleet of conventionally fueled vehicles with zero- emission vehicles.
D-6 Guidebook for Deploying Zero-Emission Transit Buses Term Definition Fuel Cell Electric Bus Zero-emission bus that utilizes onboard hydrogen storage, a fuel cell system, and batteries. The fuel cell uses hydrogen to produce electricity, with the waste products of heat and water. The electricity powers the batteries, which powers the bus. Greenhouse Gas Emissions Zero-emission buses have no harmful emissions that result from diesel combustion. Common GHGs associated with diesel combustion include carbon dioxide (CO2), carbon monoxide (CO), nitrous oxides (NOx), volatile organic compounds (VOCs), and particulate matter (PM). These emissions negatively impact air quality and contribute to climate change impacts. Gross Vehicle Weight Curb weight plus gross load. Gross Vehicle Weight Rating The maximum total weight as determined by the vehicle manufacturer, at which the vehicle can be safely and reliably operated for its intended purpose. Hydrogen Fueling Station The location that houses the hydrogen production (if produced on- site), storage, compression, and dispensing equipment to support fuel cell electric buses. Inductive Charger BEB chargers that rely on magnetic charge plates beneath roadways and a counterpart inside the bus. When an induction- capable bus passes over that charging plate, the two magnets become "tuned," and current flows to charge the onboard battery. Key Performance Indicator Critical indicator of progress toward an intended result. Motive Energy Energy consumed by mile to operate the powertrain of a ZEB. Natural Gas Reforming Method to produce hydrogen where high-temperature steam (700°Câ1,000°C) is used to produce hydrogen from a methane source, such as natural gas. In steam-methane reforming, methane reacts with steam under 3â25 bar pressure in the presence of a catalyst to produce hydrogen, carbon monoxide, and a relatively small amount of carbon dioxide. Net Power For a fuel cell, stack power minus projected balance of plant (BOP) power.
D-7 Term Definition OEM-Advertised Range Total possible vehicle range reported by the bus manufacturer. This range may not reflect the range a transit agency could expect in regular transit service. On-route Charging BEB charging while on the route. With proper planning, on-route charged BEBs can operate indefinitely, and one charger can charge multiple buses. Operating Range Driving range of a vehicle using only power from its electric battery pack to travel a given driving cycle. Overhead Charger Overhead chargers are used for fast-charge scenarios. Overhead charging equipment typically uses a pantograph, where the moving parts are on the bus, or inverted pantograph, where the moving parts are on the charger mast. Plug-in Charger BEB charging method typically used for overnight or mid-day depot charging. Most transit agencies that use plug-in charging have one charger per bus, or one higher-powered charger (i.e., 120+ kW) shared between multiple buses. Post-Delivery Inspection Inspection of each bus after it arrives at your facility to identify any defects. Part of acceptance testing. Power Rate that energy is consumed or moved, measured in kW for ZEBs. Power Factor Ratio of Apparent Power to Working Power, a measurement of how much an incoming current is doing useful work. Working Power, measured in kW, is the actual power electrical equipment requires when performing its function. For a bus charger, the working power would be approximately equivalent to the power rating of the charger (e.g., a 50 kW depot charger would have 50 kW working power). However, many types of equipment require Reactive Power to generate and sustain a magnetic field in order to operate. Working power and reactive power make up Apparent Power, which is measured in kilovolt-amperes (kVA). A high Power Factor benefits both the customer and the utility, while a low Power Factor indicates poor utilization of electrical power.
D-8 Guidebook for Deploying Zero-Emission Transit Buses Term Definition Pre-Delivery Inspection Your on-site inspector will conduct a final review of the completed bus before the OEM can release the bus to be shipped to your property. Transit agencies may elect to have the staff managing the ZEB procurement along with a ZEB bus expert visit the OEM prior to article completion to review the manufacturing processes and ensure that the bus meets quality standards and specifications. Rated Power For a fuel cell, the total power in the stack. Regenerative Braking When kinetic energy is brought back into the battery when the bus is decelerating through taxi or braking, when the motor acts as an electric generator, producing electricity that is fed into the vehicle's batteries. Reliable Range Estimate of the total expected range from a vehicle in regular transit service. The driving conditions in regular transit service (e.g., passenger load, stops and starts, traffic conditions, driver style) differ from the conditions of Altoona testing or manufacturer testing, resulting in a lower estimated range. Retirement Schedule Timing of when buses will be retired from revenue service at the end of their useful life. Revenue Service All scheduled time a bus spends serving passengers, which can also be defined as platform hours minus deadhead and layover time. Road Call A failure of an in-service bus that causes the bus to be replaced on route or causes a significant delay in schedule. Route Modeling A cost-effective method to assess the operational requirements of ZEBs by estimating the energy consumption on various routes using specific bus specifications and route features. State of Charge Quantity of electric energy remaining in the battery relative to the maximum rated amp-hour (Ah) capacity of the battery expressed in a percentage. This is a dynamic measurement used for the energy storage system. A full SOC indicates that the energy storage system cannot accept further charging from the engine- driven generator or the regenerative braking system.
D-9 Term Definition Technical Specifications Critical component of bus and charging or hydrogen fueling infrastructure procurements that define technical and performance requirements that satisfy your service needs within the constraints of your operating conditions. Tiered (or Step) Rate Electricity rate structure with distinct costs per kWh at different thresholds of consumption (e.g., $0.07 for the first 2,000 kWh, and $0.06 for all kWh above 2,000). Time of Use Rate Electricity rate structure designed to curb usage during peak windows of power consumption. Utilities charge a lower rate for electricity consumed during off -peak hours, usually in the evening or at night, and a higher rate for electricity consumed during peak hours, typically during periods when most businesses are operating. Utilization Comparison of the number of days a bus was actually put into service to the total days it was available to be put into service. Low utilization could indicate that there are operational issues, such as there not being enough operators trained on ZEBs. Tracking utilization can help identify the root cause of issues and address them. Validation Procedure to confirm that the actual bus performance is in line with expected performance. Results of validation testing can be used to refine bus modeling parameters and to inform deployment plans. Results of validation testing are typically not grounds for acceptance or non-acceptance of a bus. Warrantable End of Life Capacity A measure of battery degradation determined as the point at which the batteries can no longer provide the energy or power required to meet the design operating profile. It is expressed as a percentage of remaining battery capacity as compared with gross capacity at the beginning of useful life. For purposes of this specification, WEOL shall be a measure of the useful and intended life of the energy storage device. WEOL shall be used as a condition for battery replacement and to potentially initiate warranty claims.
D-10 Guidebook for Deploying Zero-Emission Transit Buses Term Definition Zero-Emission Vehicle A vehicle that emits no tailpipe emissions from the onboard source of power. Well-to-wheel Emissions Quantity of greenhouse gas or other harmful emissions that includes emissions from energy use and emissions from vehicle operation. For BEBs, well-to-wheel emissions would take into account the carbon intensity of the grid used to charge the buses. For FCEBs, well-to-wheel emissions would take into account the energy to produce, transport, and deliver the hydrogen to the vehicle.
