APPENDIX E
Adaptation Measures

This appendix provides detailed summaries of a number of mature, developing, and emerging adaptation measures.

Mature

These technologies have been widely adopted and are well understood.

Auxiliary Heaters

• What is it?
  • Auxiliary heaters provide heat for the cabin on cold weather days. These operate by heating water utilizing diesel fuel to produce supplementary heat. These heaters can be timer-controlled to start between 1 and 2 hours prior to engine operation.
• What can it mitigate?
  • Auxiliary heaters can mitigate range loss on cold weather days by providing additional heat to passengers and the operator. This added heat minimizes the impact on the vehicleʼs range, as it is generated without relying heavily on the onboard battery system.
• When should it be used?
  • The most efficient ZEB operation conditions are around 60°F. When air temperature drops below that level, the power needed to heat the cabin can require significant energy and reduce the available energy for driving (Joint Office of Energy and Transportation 2024b). Auxiliary heaters are typically programmed to be available to start below 40°F.
• How hard is it to implement in different contexts?
  • Auxiliary heaters are easy to install during the vehicle build, but can be difficult to retrofit.
• Does it provide Absorptive, Adaptive, or Restorative capacity?
  • Auxiliary heaters are absorptive to shocks and stressors caused by cold weather. The heaters allow the fleet to maintain normal operations if the region experiences an unexpected freeze.
• What does it cost?
  • Costs for an auxiliary heater can be part of the base vehicle cost; if not, a full system is typically less than $10,000.
• What are the day-to-day operational benefits?
  • Collateral day-to-day benefits include faster charging and improved battery longevity due to usage of a lower percentage of the available battery capacity, more reliable vehicle performance, and better heating efficiency.

Battery Thermal Management Systems

• What is it?
  • Battery thermal management systems (BTMS) include technologies and methodologies to control the battery cellsʼ temperature range to ensure optimal functionality (Olabi et al. 2022). Typically, liquid cooling systems are utilized to ensure healthy battery life in high and low temperatures. This feature is standard in most EVs.
• What can it mitigate?
  • It can mitigate adverse temperature effects on battery cell durability, power availability, and drivability.
• When should it be used?
  • During periods of high and low temperatures; typically, below 40C and greater than 15C (104°F–59°F).
• How hard is it to implement in different contexts?
  • BTMS is a standard feature on current vehicles.
• Does it provide Absorptive, Adaptive, or Restorative capacity?
  • BTMS provides absorptive capacity in cold or hot weather.
• What does it cost?
  • BTMS is an integral part of a delivered battery system and should not have a separate cost.
• What are the day-to-day operational benefits?
  • Collateral benefits include extended battery life, improved charging efficiency, enhanced driving range, increased safety, consistent performance, and improved regenerative braking.

ICE Contingency Fleet

• What is it?
  • Spare ICEBs that are maintained for use in emergencies.
• What can it mitigate?
  • Depending on the quantity retained, contingency ICEBs could be used for emergency services if the ZEB fleet range is insufficient to meet service needs or to provide service when charging or hydrogen is unavailable.
• When should it be used?
  • As an agency begins its transition to ZEBs, the existing ICE fleet will continue to operate in various adverse conditions, supported by the existing ICE fueling and maintenance. As the agency approaches a full transition to ZEBs, the ICE contingency fleet will need to be retained more intentionally.
• How hard is it to implement in different contexts?
  • As the transition to ZE buses progresses, maintaining separate infrastructures for ICE and ZE fueling and maintenance will require additional space and resources. The additional buses themselves will also require extra storage space. Having a larger fleet may result in exceeding the FTA spare ratio, and working with other government agencies to ensure compliance with regulations (see Santa Maria Regional Transit Case Study).
• Does it provide Absorptive, Adaptive, or Restorative capacity?
  • An ICE contingency fleet allows an agency to adapt to situations where the ZEB fleet cannot meet the agencyʼs needs.
• What does it cost?
  • The cost will vary depending on the non-emergency uses (if any) for the vehicles. Typically, maintaining end-of-life vehicles costs more per mile than newer vehicles, and an aged ICE contingency fleet can exacerbate this maintenance cost. The capital cost may be low or zero if existing vehicles are kept in the fleet.
• What are the day-to-day operational benefits?
  • An ICE fleet may provide operational benefits such as flexibility to provide routes that are outside of a ZEBʼs capable range.

On-Site Fossil Fuel Generator

• What is it?
  • Typically powered by diesel, natural gas, or propane, fossil fuel generators use an engine to turn a generator and produce electricity. Generators can easily meet the needs of basic energy loads but require additional equipment to be paired with loads that ramp up demand quickly, such as electric vehicle supply equipment (EVSE). Most generators can include selective catalytic reduction (SCR) and filter systems to reduce criteria and particulate emissions to acceptable levels to meet air quality standards.
• What can it mitigate?
  • A generator can provide power during normal utility operations (parallel generation) but can require additional emissions reduction technologies like selective catalytic reduction (SCR) to meet local emissions requirements. Additionally, regulations can require generators to operate only a set number of hours a year.
  • A generator can also be utilized in stand-by operations to provide backup power during a power outage, where regulations on emissions are typically more relaxed than during prime power.
  • Can be sized for the entire load at a site or just for critical loads.
  • Offers resilient power at sites and potential economic savings during normal or peak operations.
• When should it be used?
  • During an outage, generators can provide power to the site if fuel is available.
• How hard is it to implement in different contexts?
  • Generators are the incumbent power producer for behind-the-meter energy resources, utilized for over 100 years. Pairing generators with other energy sources like EVs, solar, and battery storage requires a control system to work with these assets, similar to how a microgrid operates. However, the scale of power required for EV charging is significant, and generators of that size may not be straightforward or cost-effective to implement.
• Does it provide Absorptive, Adaptive, or Restorative capacity?
  • Generators significantly improve the restorative capacity at a site by providing power or fuel to vehicles when utility service is unavailable. During peak energy events, when the utility may have low energy reserves, a generator can provide supplemental power to the site, thereby reducing the load burden on the utility. Generators are highly resilient and flexible during outages, but controls must be adjusted for the charging infrastructure to avoid high ramp rates.
• What does it cost?
  • Costs vary based on fuel type and duty cycle requirements. Generators intended for higher duty cycles and cleaner operations are more expensive, while backup-only diesel systems are lower in cost. A typical natural gas generator for high duty cycles ranges from $700 to $2000 per kW for hardware and installation, depending on the generatorʼs size. When including a SCR unit for particulate emissions reduction, prices range from $900 to $2600 per kW.
• What are the day-to-day operational benefits?
  • Generators with SCRs may be able to operate in parallel with the utility for a certain number of hours annually to reduce utility costs by lowering peak demand.

Shades for Bus Parking

• What is it?
  • Semi-permanent to permanent structures providing shade over fleets.
• What can it mitigate?
  • Shades reduce heat build-up during warmer months within parked fleets, charging stations, and power supplies. This can extend the life of assets, reduce the energy required to cool down people and assets, and increase charging efficiencies.

• When should it be used?
  • During warmer months
• How hard is it to implement in different contexts?
  • Shades can be semi-permanent or permanent, with various options available. Shades can be installed in different forms, such as metal structures or collapsible fabric systems. These shades can also provide protection against ultraviolet light, rain, hail, and lightning.
• Does it provide Absorptive, Adaptive, or Restorative capacity?
  • Shades provide absorptive capacity to high temperatures.
• What does it cost?
  • $3,000–$30,000
• What are the day-to-day operational benefits?
  • Collateral benefits include improved battery temperature control, extended battery life, protection of charging infrastructure, and reduced wear and tear on vehicles.

Staff Emergency Training Programs

• What is it?
  • Training staff at all levels is critical for effective emergency response, and introducing ZEBs and supporting infrastructure into a transit operation will require an increase in training modules compared to the baseline in the near term. Training should be provided to transit employees in both a classroom setting and hands-on demonstrations, and it should reflect security and emergency plans and procedures typically contained within an agencyʼs Public Transportation Agency Safety Plan and/or System Security and Emergency Preparedness Plan (FTA 2016, 2024). Hands-on demonstration trainings should be documented with a trainerʼs and traineeʼs signatures and the dates the training took place (FTA Bus Safety Program 2018). Transit employees (bus operators, supervisors, and dispatchers) must be included in training because these individuals are the first responders to an emergency on their vehicles.
  • It is important to keep SOPs, checklists, plans, and documents up to date for training and documentation purposes. A transit agency should provide classroom, hands-on, and refresher training on vehicle emergency response procedures. In addition, the agency should provide formal training for supervisors and dispatchers on how to carry out emergency response procedures (FTA Bus Safety Program 2018). Providing training on the National Incident Management System Incident Command System is necessary when staff and equipment are mobilized for a regional emergency.
• What can it mitigate?
  • Training can assist staff in emergency situations specific to ZEBs, such as battery thermal events and collisions, as well as standard transit emergency situations.
• When should it be used?
  • Formal, informal, and refresher training should be provided periodically, especially following an emergency event. While an agency should not wait for an emergency to update or provide training, an emergency event can provide an agency with new information on risks. Following an event, an agency should review materials and procedures to see if they are still useful and encompass relevant risks.
• How hard is it to implement in different contexts?
  • Training may require planning, costs, time, agency equipment, and third-party representation (such as a fire department for a fire demonstration or passenger advisory groups). Therefore, implementation can range in complexity based on how much coordination and agency resources are required and available.
• Does it provide Absorptive, Adaptive, or Restorative capacity?
  • Trainings allow staff to adapt to emergency situations through established procedures. These trainings, in turn, can allow an agency to recover and return to normalcy after an event.

• What does it cost?
  • Costs can vary based on the type and length of the training, as well as the number of individuals to be trained. Grants for training may be available in relation to emergency preparedness or mitigation.
• What are the day-to-day operational benefits?
  • Collateral benefits include operational efficiency resulting from optimal driving practices, enhanced customer satisfaction, regulatory compliance, smoother implementation of new technologies, strengthened organizational culture, and improved staff morale and retention.

Utility Equipment Redundancy (Dual Feeds, Secondary Service)

• What is it?
  • A high consumer of electricity can build resilience into a site by procuring a redundant service from their utility. The second utility service typically comes from a separate circuit, ensuring availability if one service goes down. Facilities often use a Main-Tie-Main configuration for easy automatic switching between services during an outage.
• What can it mitigate?
  • Automatically switches to redundant utility service if one service experiences an outage.
• When should it be used?
  • Deciding to request multiple utility services involves a cost-benefit analysis. The infrastructure is more expensive and requires greater coordination and testing with the utility, but it provides enhanced security against intermittent outages. See the Metro Transit Case Study Example.
• How hard is it to implement in different contexts?
  • For new facilities, this requires coordination with the utility and additional commissioning to ensure functionality. Existing facilities typically require removing and installing a new switchgear.
• Does it provide Absorptive, Adaptive, or Restorative capacity?
  • Multiple utility services can absorb short-term outages of one service with minimal site impact. During a complete outage, the utility has two options to restore power, potentially solving the problem sooner than with a single service.
• What does it cost?
  • Significant costs compared to a typical single-service installation, with total costs highly dependent on each utilityʼs additional electrical service charges.
• What are the day-to-day operational benefits?
  • There are no day-to-day benefits of the redundant service.

Developing

These technologies have been implemented at various transit agencies, but standard approaches to implementation are still being developed.

Charge Management

• What is it?
  • Charge management software operates as a software layer, either on the cloud or a local controller, allowing for both local and system-level control of the charging infrastructure. It can be optimized with algorithms that prioritize vehicle charging, reduce demand, and avoid costly time-of-use pricing.
• What can it mitigate?
  • Prevents exceeding the maximum demand available from the utility or microgrid.
  • Ensures vehicles are charged in time for their routes.

• • Manage charging loads in cases of reduced grid capacity or outage.
  • Reduce costs associated with charging and avoid unnecessary cost impacts.
• When should it be used?
  • It can be important for sites with limited capacity and microgrids to maximize charging infrastructure utilization. Depending on the local context, it may be able to reduce operating costs for charging.
• How hard is it to implement in different contexts?
  • Charge Management providers continuously add new charger OEMs to their platforms, simplifying the integration process. Although chargers can be pre-integrated, each site requires some straightforward integration work to become operational. Having more charger OEMs or models within the same charge management network may increase the complexity of charge management software implementation.
• Does it provide Absorptive, Adaptive, or Restorative capacity?
  • Charge Management adapts to fluctuations in bus operations by continuously optimizing the charging strategy based on available information. It offers restorative benefits by matching charging electricity demand with resilient backup power capacity to ensure system functionality. However, systems relying entirely on the cloud are susceptible to local network quality issues. Providers should aim to utilize both cloud and local control to maintain high uptime.
• What does it cost?
  • The cost varies depending on the level of service purchased from a provider. Charge management software without hardware or service level agreements ranges from $1500 to $2500 per direct current fast charging port.
• What are the day-to-day operational benefits?
  • May reduce infrastructure costs and involve smaller construction footprints, despite increases in fleet sizes.
  • Reduces demand charges and peak pricing periods.
  • Since charge management is constantly optimizing the charging operations of the site, it can easily adjust to changing energy tariffs that could shift charging operations to different time periods. As electrification grows, utilities will change their energy tariffs and time-of-use periods to better match the needs of their evolving generation mix.

Fuel Supply Diversification

• What is it?
  • Fuel supply diversification involves utilizing multiple energy sources to generate electricity, thereby reducing dependence on any single fuel source. This approach can include a mix of renewable and non-renewable energy sources. Having distributed energy resources like solar photovoltaics (PV), battery energy storage, and fuel cells on site and pairing them with a utility connection allows for multiple sources of electricity for fueling vehicles.
  • For fleets with FCEBs, fuel supply diversification can entail ensuring that there are multiple sources of hydrogen production that can be accessed by the transit agency in the event of an issue at the primary production facility providing fuel used to support the vehicles.
• What can it mitigate?
  • Avoids fuel supply disruptions and price volatility.
  • Mitigates the effect of external influences (i.e., geopolitical issues) by having multiple supply chains for fuel.
• When should it be used?
  • Fuel supply diversification is generally advisable for all resilient energy systems to avoid single points of failure.

• How hard is it to implement in different contexts?
  • The complexity of implementing fuel supply diversification depends on the specific situation. Utilizing technologies like microgrids, solar PV, battery storage, generators, or hydrogen as fuel are all methods to implement this concept into a depot. Multiple sources of hydrogen supply can often be accessed, though the distance between a transit agency and a secondary production facility may be much greater than the distance between a transit agency and a primary production facility, resulting in significantly different fuel costs depending on the source of supply.
• Does it provide Absorptive, Adaptive, or Restorative capacity?
  • Fuel supply diversification is an absorptive measure, providing access to multiple energy supply sources if one were to become unavailable. It is also an adaptive and restorative measure, reducing the burden on any single resource and allowing multiple pathways to restore power to a site.
• What does it cost?
  • Utilizing various sources of energy for fuel supply diversification incurs costs associated with those energy systems, but it is not an additional cost beyond implementing those systems. These costs are highly dependent on the fuel production source.
• What are the day-to-day operational benefits?
  • With multiple sources of fuel for the fleet, the operator can optimize the consumption of energy by using the lower-cost option when it is available.

Local Control of Assets

• What is it?
  • Local control of energy systems is the capability to manage and operate energy assets both locally (on-site) and remotely (via network connections). This is a critical requirement for resilient transit depots. Relying solely on network and remote connections can produce unreliable services, as any network failure can lead to operational downtime. Conversely, relying solely on local control can result in unoptimized performance and increased operational costs.
  • Local control ensures that systems continue operating in a prescribed manner without requiring a network connection. This is particularly important during outages or times when the network signal is weak. Local control can be implemented through on-site control units that manage the energy assets directly or through pre-programmed controls that activate during network outages.
  • For example, utilizing local control for charge management software allows for the continuous operation of the charging infrastructure even during connectivity issues. Many problems with the charging infrastructure in the field stem from downtime due to connectivity issues. By incorporating a local controller into the charge management software, the system can maintain control over the charging process regardless of network availability, thereby increasing uptime and the overall reliability of the charging infrastructure.
  • During major events where utility power is cut and emergency operations are in effect, it is crucial to have multiple pathways to charging vehicles. It is a safe assumption that internet access might not be available during such events. Therefore, local control of assets ensures that essential operations can continue uninterrupted.
• What can it mitigate?
  • Mitigates the effects of network connectivity issues.
• When should it be used?
  • Local control should always be available to avoid over-reliance on providers for on-site visits or network reconfiguration.

• How hard is it to implement in different contexts?
  • Implementing local control is relatively simple but requires upfront vetting of vendors to ensure they can provide both local and remote connectivity.
• Does it provide Absorptive, Adaptive, or Restorative capacity?
  • Local control benefits the adaptive and restorative nature of a resilient transit depot. It ensures continued charging operations with local generation during network outages. Switching between network and local control allows quick system adjustments in case of poor network connectivity.
• What does it cost?
  • Providers are beginning to offer local control to address downtime issues, often at a premium compared to internet-only control approaches. Microgrid controls are typically designed to operate without internet connectivity for resilient operations.
• What are the day-to-day operational benefits?
  • During normal operations, local control can ensure continued operation of chargers, solar PV, battery storage, and generators during times of poor network connectivity.

Microgrid

• What is it?
  • A microgrid is a localized group of electricity sources and loads that can operate independently from the larger grid. It includes energy generation (such as solar PV or natural gas generators), energy storage (like battery energy storage), and controllable loads such as EV charging, all managed by an advanced control system. This system optimizes for cost, resiliency, and sustainability. Microgrids can operate without the utility by utilizing their own “grid-forming entity” that establishes the gridʼs voltage and frequency. Typically, these entities can be either the generator or the battery storage system, depending on the microgrid architecture.
• What can it mitigate?
  • Mitigates the impact of power outages, enhances energy quality, and improves the resilience of the available power supply.
  • Reduces the need for additional utility capacity and manages energy flows to lower utility costs.
• When should it be used?
  • Microgrids are ideal for locations requiring high reliability, such as transit depots, cold storage facilities, and critical infrastructure. They are also beneficial in remote areas where connecting to the main grid is not feasible or cost-effective.
• How hard is it to implement in different contexts?
  • The complexity of implementing a microgrid varies significantly by location. In urban areas with existing infrastructure, integration can be more straightforward but may face additional regulatory requirements and space constraints for energy assets. In rural areas, there may be more space for energy assets and simpler regulatory requirements, but the reliance on the microgrid can be very high if the utility is not available, affecting the implementation approach.
• Does it provide Absorptive, Adaptive, or Restorative capacity?
  • Microgrids can quickly adjust to changes in energy supply at the site, adapting to new operating parameters or energy supply shortfalls. They are constantly optimizing for multiple variables, including cost reduction and maintaining backup power capacity. Microgrids can also prepare for outages or major storms by ensuring the battery is fully charged. They can restore power autonomously after disruptions, quickly getting facilities back online.
• What does it cost?
  • Microgrid costs are highly variable due to the unique resources involved in each installation. Generally, microgrids providing 4-6 hours of backup power can offer a positive net present value (NPV) in most utility markets, with a rough price of $0.10–$0.25/kWh, depending

• on the systemʼs size. For highly resilient systems, costs can increase by 20–40% depending on the equipment used.

• What are the day-to-day operational benefits?
  • During normal day-to-day operations, the same energy resources that can provide resilient power are also utilized to reduce utility consumption and energy costs.

On-Site Solar Generation and Battery Storage

• What is it?
  • On-site solar generation involves installing solar PV systems to capture sunlight and convert it into electricity. Solar PV is non-dispatchable, meaning it cannot provide power at any moment. Battery energy storage systems (BESS), typically lithium-ion batteries, are installed on site to store excess solar energy or charge from the grid for use at different times. A BESS is a dispatchable asset, meaning it can be controlled to provide power at any time. Combining solar and battery storage allows an agency to produce electricity on site and directly reduce load or charge the battery to utilize when needed.
• What can it mitigate?
  • The storage can be charged from either solar or the grid, allowing it to be considered a firm capacity resource.
  • For solar and storage to operate during an outage, microgrid controls and controllable breakers must be installed.
• When should it be used?
  • Solar can typically provide direct cost avoidance in most geographies by avoiding costly utility energy. In markets with high energy and demand charges, adding a battery can further reduce costs. For resilience, both systems are used to provide backup power, but a generator is typically required for a highly resilient system.
• How hard is it to implement in different contexts?
  • Solar and storage without microgrid functionality are mature technologies and relatively simple to implement in most markets. Utility requirements can influence the economic appeal, but generally make sense for on-site consumption. Adding microgrid controls and switchgear is more complex, requiring an experienced microgrid provider to ensure robust controls and sequence of operations for resilient power during an outage.
• Does it provide Absorptive, Adaptive, or Restorative capacity?
  • Pairing battery storage with solar creates a highly adaptive energy system that can directly reduce load through solar and reduce demand through battery storage. During an outage, solar and storage microgrids can restore limited power, although predictability decreases. Backup power can range from a few hours to 12+ hours, depending on the systemʼs design and the siteʼs energy needs.
• What does it cost?
  • The cost of solar paired with battery storage varies due to the different installation methods, like rooftop, carport, and ground-mounted. Generally, solar and battery storage can provide a positive NPV in most utility markets and facility loads, with a rough price of $0.15–$0.25/kWh, depending on the systemʼs size.
• What are the day-to-day operational benefits?
  • Mitigates peak demand and provides additional on-site power during day-to-day operations. This can reduce operating costs for a transit agency.

Cybersecurity and Software Adaptations

• What is it?
  • Cybersecurity and software adaptations are technology measures that are increasingly relevant as wireless connectivity, AI, and software management systems are used throughout

• transit. While cybersecurity measures are not new, they need to be applied to emerging systems such as charging hardware, firmware, and software. Existing adaptations should be evaluated and adopted for ZE fleets. These include:
  • Physical security to prevent unauthorized access to electronics on vehicles, EVSE, or refueling equipment (APTA 2019).
  • Software vulnerability assessments or penetration testing by third-party consultants to proactively find, contain, and repair bugs.
  • Request cybersecurity testing and compliance with existing standards by OEMs during the procurement process (K & J Safety and Security Consulting Services 2023).
  • Creating Incident Response Plans to contain, remediate, and recover from potential attacks on ZEB systems while continuing operations, which may include conducting tabletop exercises (K & J Safety and Security Consulting Services 2023).
  • Creating protocols and procedures for conducting software updates with minimal disruption.
  • Increased cybersecurity can include creating a centralized operations center where information technology can be combined with physical operational technology (DOE Office of Policy 2017). This may require building out a new organization within the agency or partnering with regional stakeholders.

• What can it mitigate?
  • Software and cybersecurity adaptations can mitigate a variety of disruptions to charging and energy management that could be caused by incompatible software updates, malicious attacks, or any other incident that disables regular software use.
• When should it be used?
  • Cybersecurity and software adaptations should be used concurrently with all transit agency operations and expanded as the ZE transition occurs.
• How hard is it to implement in different contexts?
  • ZE cybersecurity measures will depend on existing agency cybersecurity practices. Larger agencies with dedicated personnel may have less difficulty. Contracting with third-party consultants for assessments may be necessary.
• Does it provide Absorptive, Adaptive, or Restorative capacity?
  • Preventative measures such as physical security, cybersecure procurement requirements, and vulnerability assessments will help an agency absorb disruptions. Related Incident Response Plans and ensuing measures will help an agency adapt and restore service in the event of an incident.
• What does it cost?
  • Costs may vary from low to high and are often considered recurring costs due to software licensing requirements and ongoing managed services. However, costs may be contingent on the level of service provided by the vendor.
• What are the day-to-day operational benefits?
  • Beyond the primary role in protecting data and systems, these adaptations enhance operational efficiency through automation of tasks, streamlined processes, reduced system downtime, improved data integrity and availability, regulatory compliance, enhanced user experience, and improved cybersecurity culture.

ZE Workforce Training

• What is it?
  • Workforce Training is education that enables the existing workforce or industry members to develop and master the skills needed for the ZE transportation environment. Some educational training examples include how to operate and maintain new ZE vehicles, safely

• operate and maintain charging infrastructure, and understand the benefits and limitations of the new technologies.

• What can it mitigate?
  • Proper workforce training can mitigate long vehicle downtimes by ensuring that the current workforce has the knowledge and skills necessary to fix or identify problems with the new vehicles or chargers.
• When should it be used?
  • In general, workforce training should be a part of every ZE plan as it will empower individuals to understand and excel in the new operating environment that comes with the ZE transition. This can mitigate resistance to change and produce a resilient ZE fleet that can react to technical or operational issues that will arise with the new fleet.
• How hard is it to implement in different contexts?
  • General principles can be easily applied to the electrification technology and vehicles to provide the workforce with a basic understanding of the ZE technology.
  • Additional training should be utilized to account for the unique operations of each fleet, including route/driving/weather effects on vehicle performance, hands-on training with the specific charging infrastructure/software at the site, and scenario planning for proper operations during normal and emergency operations.
• Does it provide Absorptive, Adaptive, or Restorative capacity?
  • Proper training will allow fleets to get back up and running quicker and become less reliant on third-party resources.
  • During an emergency, scenario training can empower the workforce to make the proper adjustments and updates to operations to properly adjust to a new operating scenario.
• What does it cost?
  • Workforce Training can be time-intensive to create new training materials and match them to the fleetʼs unique operations.
  • In order to save time and cost, leverage partnerships with the Bus and Fueling Infrastructure OEMs for educational material unique to your design. Utilize industry partners to curate general ZE educational materials and reduce the amount of training material that must be created unique to the fleet.
• What are the day-to-day operational benefits?
  • Having an in-house understanding of how the overall ZE system operates ensures that staff safety is maximized, mistakes are avoided, and time or energy is not wasted.

Emerging

V2G/V2B

• What is it?
  • Vehicle-to-Grid (V2G) and Vehicle-to-Building (V2B), sometimes collectively referred to as Vehicle-to-Everything (V2X), are concepts where the energy stored in electric vehicles (EVs) can be used to power other loads through bidirectional charging. V2G involves sending energy from the vehicle back to the grid, supporting the grid during peak demand or outages. V2B, on the other hand, allows energy to be transferred from the vehicle to a building, providing backup power or supplementing the buildingʼs energy needs. This technology leverages the batteries of EVs as mobile energy storage units that can be integrated into the energy management systems of grids or buildings.
• What can it mitigate?
  • V2B provides additional backup power to buildings during outages, while V2G can provide wider resilience to the grid by supplying power during peak demand times.

• When should it be used?
  • V2G is highly dependent on fleet operations and requires vehicles to be stationary and charged to be useful. Many fleets aim to utilize their vehicles as much as possible, leaving minimal time for V2G benefits. However, integrating V2B capabilities into resilient facilities can be valuable for emergency planning, allowing these assets to serve as backup power during critical times.
• How hard is it to implement in different contexts?
  • V2G/V2B technology is still in pilot phases with a few proven use cases, such as school bus depots. Developing a robust V2G use case involves significant hardware and software integration, often custom-made for each site. Many vehicles and bidirectional chargers have not been extensively tested for integration, and comprehensive energy management systems required for controlling the entire setup are in the early stages of commercial viability. Thus, implementing V2G/V2B can be labor-intensive and complex.
• Does it provide Absorptive, Adaptive, or Restorative capacity?
  • If effectively utilized, V2X can serve as an adaptive and restorative measure by providing resilient energy directly where it is needed. For instance, vehicles can be moved to community centers or other critical facilities to supply power during emergencies.
• What does it cost?
  • The cost of implementing V2G or V2B is highly variable and typically comes at a premium compared to standard installations. Many necessary products and services have recently entered the market and have not been deployed at scale, which contributes to the higher costs.
• What are the day-to-day operational benefits?
  • By charging a vehicle during off-peak hours and supplying the grid during on-peak hours, V2G creates potential revenue from utilities if enrolled in a V2G program by supporting grid stability, such as the Emergency Load Reduction Program in California; however, the vehicle must be parked rather than in service during these opportunities (California Public Utilities Commission n.d.).

Fuel Cell Generators

• What is it?
  • Fuel cell generators produce electricity through a non-combustion process using a range of fuels, but most commonly with natural gas or hydrogen. These generators are relatively power-dense and established technologies for electricity generation. Fuel cells operate by converting chemical energy from the fuel directly into electrical energy through an electrochemical reaction, without combustion, which results in lower emissions.
• What can it mitigate?
  • Reduces utility power consumption by providing a continuous baseload power.
  • Serves as a backup power source during outages.
• When should it be used?
  • Fuel cells are typically used in a non-dispatchable function, meaning they provide a consistent baseload power rather than being used on-demand. To generate a return on investment, fuel cells should be used as much as possible due to their higher upfront costs.
• How hard is it to implement in different contexts?
  • Implementing fuel cells requires a certain level of expertise, but the technology is relatively mature. Regulatory frameworks often favor fuel cells, simplifying the installation process. However, maintenance and warranty issues can be more frequent compared to other assets, and replacing the fuel cell stack is a common occurrence.
• Does it provide Absorptive, Adaptive, or Restorative capacity?
  • Fuel cells capable of adjusting output quickly can act as a restorative measure by providing power during an outage. To ensure proper operation, fuel cells are often paired with battery storage systems to handle dynamic load changes and provide additional resilience.

• What does it cost?
  • This can vary widely depending on the use case. Fuel cells are generally more expensive to implement than diesel generators.
• What are the day-to-day operational benefits?
  • During day-to-day operations, the continuous power output can consistently reduce the load on the utility but is not generally used as a flexible, dispatchable asset.

Linear Generator

• What is it?
  • A linear generator is a power generation system that utilizes a non-combustion, compression-based reaction to produce electricity. Since it is based on a flameless compression reaction, there are very low criteria pollutant emissions that meet the most stringent of emissions regulations. The system technology can utilize natural gas, biogas, hydrogen, ammonia, syngas, and even some alcohols without compromising performance.
• What can it mitigate?
  • A linear generator can provide electricity during an outage scenario. Linear generators can ramp up to meet demand quickly and pair well with the transient loads of EV Charging.
• When should it be used?
  • Linear Generators are a relatively new technology and are typically used as a baseload resource operating for every hour of the year. Utilizing the generator to produce energy at all times further improves the long-term economics of the system. When paired with battery storage, the microgrid can meet peak loads that are greater than what the linear generator can meet on its own.
• How hard is it to implement in different contexts?
  • Linear generators are growing in power density but currently have a footprint of about a parking space to produce 250 kW of power. In order to get to megawatt levels of power generation, a large amount of square footage would need to be set aside for the system. It is expected that as the technology matures, the power density will increase further and reduce this requirement.
  • The fuel flexibility characteristics allow for the generator to be placed in service in multiple scenarios. Many of the current deployments are touted as “Hydrogen-Ready” due to the relatively easy swap of hydrogen as fuel in the generator.
• Does it provide Absorptive, Adaptive, or Restorative capacity?
  • Linear generators can adjust to new power requirements quickly, but due to the current power density, they are not realistic to meet the peak load of a site. When paired with battery storage, the microgrid can adjust to short-duration peak loads and still produce enough power for the entire site if needed. They are regularly used within off-grid and on-grid microgrids and have proven to be a reliable source of power at these sites.
• What does it cost?
  • Due to linear generators being a relatively new technology, the cost per kWh of energy is competitive in high energy cost markets but may come at a premium where electricity rates are below average. They typically run every hour of the year to produce enough kWh to buy down the cost of the system, but the system costs are declining each year.
• What are the day-to-day operational benefits?
  • Linear generators can reduce peak loads to reduce utility demand costs in normal operation.