Preparing Your Airport for Electric Aircraft and Hydrogen Technologies (2022)

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112 C H A P T E R   1 2 Electric aircraft are going to significantly change the electric demand profile of airports. The largest aircraft will require large, new power supplies to charge the batteries. The largest impact on power demand is the turnaround time. A faster turnaround time will require faster-charging speeds, or potentially another new technology like battery swapping. According to the calculations produced using the Assessment Tool, electric aircraft are only a portion of the expected load growth in the next 20 years. The tool has baseline assumptions for electric aircraft adoption that can be changed by the user of the tool. Electric aircraft could be as little as 10 percent of electric load growth, or could be up to 50 percent of that growth, depending on the acceptance of electric aircraft and acceptance and use of other electric transportation, eGSE, and all-electric heating, ventilation, and air conditioning (HVAC) acceptance. As part of this tool, assumptions regarding the battery sizes, charger speeds, and potential gate occupancy times were made based on the market assessment prepared for ACRP Project 03-51 (Table 19). 12.1 Existing Charging Standards Most U.S. light- and heavy-duty vehicles are gravitating toward the Combined Charging System (CCS) standard, which is a robust standard that can get up to a 400-kW charging rate. Even 1,000 kW+ charging standards are working on making sure that they are backward compatible with the CCS standards to support future-proofing fleets. This means that, even with a new charger, you could still charge an old vehicle using a previous CCS standard, or you could use an old CCS charger to charge a newer standard vehicle, just not at the vehicle’s maximum charge rate potential. Because the CCS combination has already been deployed widely on ground vehicles, the research and development have been done and troubleshooting completed. The one caveat to this is that the charging mechanisms that reside on the aircraft will likely have to go through FAA certification, but this is true for any charging method, be it proprietary, battery swap- ping, an existing charging standard, or an all-new one. Some industry partners do not believe that the CCS Combi 1 (CCS1) standard will meet their needs due to battery size and mission characteristics. Another heavy-duty charging standard that is currently restricted to use by buses is the Society of Automotive Engineers (SAE) J3105. This standard uses a hands-free automated coupler to attach to the top of the bus. This can achieve charge speeds up to 600 kW and will increase in the future. No existing electric aircraft manufacturers are using this specifically, but it may act as a template for some manufacturers. It is recommended that aircraft manufacturers work toward a unified standard, regardless of whether it is a new, e-aircraft-specific standard, or an existing standard such as CCS1. Electric Aircraft Demand

Electric Aircraft Demand 113   12.2 Proprietary Charging Standards Many aircraft manufacturers have implemented custom proprietary charging connectors to meet their specific needs on early prototypes. This is beneficial because it allows the manufacturer to manage the design requirements and charging needs of the specific aircraft rather than cater the aircraft to a specific standard. However, when deployed to scale, if each manufacturer requires its own high voltage DC charger, it could add substantial requirements to how the grid is built and how operations function at the airport. Part of this is due to utility and code requirements that require switchgear and electrical service to be sized for maximum power-draw capacity, even if not all chargers are used at the same time. Note that existing eGSE use a proprietary charging standard that was developed years ago. The market has been too small to force a need for standardization, but some manufacturers offer plug options for compatibility with other manufacturers. 12.3 Battery Swapping Solutions One potential technology solution to electric aircraft demand is battery swapping. The aircraft is designed in such a way that the battery is easily removed from the plane when it is on the ground and, rather than charging the battery on the tarmac or at a dock, a new, fully charged battery is swapped into the aircraft, and the depleted battery is then taken to a charging area where it can recharge. The FAA does not fully support this option at this time, but this solution may be re-examined if manufacturers continue to support it. Several possible benefits to battery swapping include: 1. The turnaround time on an airplane can be greatly reduced. Often, commercial planes are on the ground for approximately half an hour before their next flight. This is too small of a window for current charging and battery technology to adequately recharge a battery for the next flight. However, with a battery swap, a fully charged battery could be installed into the aircraft in about 15 minutes. The charging industry is continuing to advance faster-charging standards in its effort to compete with battery swapping, but this is not available today. 2. Demand on the grid is lower. Even if the total energy, measured in kilowatt-hours, is the same, being able to charge a battery at a slower rate, measured in kilowatts, helps prevent stress on the grid. To charge at a higher kilowatt rate, infrastructure may need to be upgraded to provide that burst of power to the site. Higher charge rates can also lead to demand charges that hurt the economic feasibility of electric vehicles since the “fueling” cost can become inflated. Battery swapping allows for a much lower kilowatt usage but requires charging the Mission Capacity Assumed Battery Size (kWh) Assumed Charger Speed / Output Power (kW) Gate Occupancy Time (min) Air Carrier Short Range (700 miles) 2 pilots + 39 passengers 4,000 600 60 Air Taxi Very Short Range (420 miles) 1 pilot + 3 passengers 480 60 60 Commuter Short Range (650 miles) 2 pilots + 9 passengers 900 400 60 General Aviation Flight Training, Private, Recreational 1 pilot + 1 passenger 42 20 60 Military Short Range (700 miles) 2 pilots + 39 passengers 4,000 600 60 Table 19. Assumptions of the Assessment Tool.

114 Preparing Your Airport for Electric Aircraft and Hydrogen Technologies batteries somewhere on the site, which could take a day to charge. As long as the operator has a fresh bank of batteries available for the next day’s flights, additional electrical infrastructure upgrades may not be needed, or at least the needs could be greatly reduced. 3. A better solution for small seaplanes. Electrical upgrades to provide high power DC to an aquatic plane can be costly to upgrade, and existing “shore power” technologies do not pro- vide high enough power to fully charge a plane between flights. While in the water, it can be difficult to access battery compartments to do a battery swap on these aircraft. However, the “Beaver” type seaplane can be electrically lifted out of the water to perform a battery swap. Possible negatives to battery swapping are as follows: 1. Increased/different maintenance needs. All charging systems will require maintenance, regardless of whether they are a battery swap setup or stand-alone fast chargers. However, battery swapping adds a mechanical component beyond traditional plug-in charger methods. Any time mechanical components are added, it increases the probability of a point of failure. Battery swapping is especially prone to this, especially if each aircraft has multiple battery swaps per day. In addition to possibly harming the batteries from frequent swaps, the aircraft or battery itself could also be damaged during a battery swap. For seaplanes, it would also increase the number of times the lifts are used every day, which also could increase lift mainte- nance requirements. 2. Infrastructure differences. Battery swapping could require more space or more overall energy, even if the peak kilowatts needed are not as high. Instead of charging one or two batteries at a time at a high rate, the facility must have the space and power to slowly charge multiple batteries overnight to make sure there is enough battery capacity for next-day opera- tions. While this does shift demand from on-peak hours to off-peak hours, it presents a set of operational challenges. In addition, airports that the aircraft may fly to would also need the same battery swapping technologies, and that can be trickier as far as who owns the actual batteries; with fast charging, there is no change in ownership. One potential alternative to battery swapping technology is stationary batteries integrated into DC fast chargers. This technology could use a lower peak input of electricity, then a much higher peak electric output to the electric aircraft batteries. Several companies are working on this technology. Table 20 provides a pro/con comparison of e-aircraft demands. Charging Method Pros Cons Battery Swapping • Currently faster layover times meet a better operational case for aircraft. • Peak power needed could be lower. • Possibly more effective for seaplanes. • Increased maintenance risks. • Possible damage to aircraft during swapping. • Infrastructure may require more space. • Legal questions on battery ownership when swapping batteries at different airports. • Currently lacks FAA support. CCS/Standardized Charging • Known standard already vetted with ground electrical vehicles. • Equipment more readily available and cost effective. • Backward compatible with future technologies. • Limited by standards to <400 kW charging speeds. • High power charging may have tougher impact on the grid. • Depends on acceptance of this standard by manufacturers and use case. Proprietary Charging Standard • Customized per aircraft to suit specific needs. • Could be faster to market or allow for different charging profiles with specific battery technologies. • Not standardized so different aircraft may not use the same charger. • May cause operational issues as the industry adapts to multiple proprietary methods. Table 20. Electric aircraft demand conclusions.