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

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

85   C H A P T E R   8 8.1 Introduction The total number of active electric aircraft is expected to remain low until at least 2030. During this period, impacts on airside facilities will likely center on the initial infrastructure necessary to support early electric aircraft operations. Beyond 2030, investment and utilization into electric aircraft among flight operators should increase. Although this shift is expected to occur gradually—likely taking over a decade to manifest starting no earlier than 2030—it will have a meaningful impact on the airside. Suitable aircraft stands and gate facilities enable aircraft servicing and the movement of passengers and freight in and out of the plane. The primary impact of electric aviation on gate facilities will be the ability to supply aircraft with electricity and hydrogen with minimum impact on the turnaround time. Different energy vectors and technical solutions are being explored by the electric aircraft industry to deliver power to the electric powertrain (Figures 38–43). The two main options for storing and delivering electrical power to the engine are (1) electrochemical batteries that deliver electricity to the engine, and (2) fuel cells that convert hydrogen (and air) into electricity (and water). The following recharging/refueling solutions are being considered for these two energy storage and delivery options: Electric charging of high-capacity batteries: • Recharge by fixed ground chargers, also known as charging stations. • Recharge by the mobile supercharger on batteries (truck or trailer). • Battery swap at the gate (batteries are recharged separately). Hydrogen, or H2, refueling for powering fuel cells: • Refuel H2 from a hydrant system. • Refuel H2 from a tanker (truck). • Swap H2 containers. Table 12 summarizes the different energy vector combinations applicable depending on the propulsion system and the technology (batteries or fuel cells). Table 13 presents recharge and refueling technologies. 8.2 Electric Charging Infrastructure To replenish electric and hybrid-electric aircraft batteries, electric charging infrastructure will be a core infrastructure requirement for any airport seeking to support electric aircraft operations. Airport planners must consider the power requirement, location, funding, and ownership of these charging facilities. Airside Requirements

86 Preparing Your Airport for Electric Aircraft and Hydrogen Technologies Figure 38. Electric aircraft charging via xed charging stations. Figure 39. Electric aircraft charging via a mobile supercharger. Figure 40. Electric aircraft battery swap. Figure 41. Aircraft refueling from a hydrant system.

Airside Requirements 87   Figure 42. Aircraft refueling by fueling truck. Figure 43. Aircraft H2 container swap. Propulsion System All-Electric Turboelectric Series Hybrid Parallel Hybrid Series/Parallel Hybrid Batteries Electricity Electricity & Aviation Fuel Electricity & Aviation Fuel Electricity & Aviation Fuel Electricity & Aviation Fuel Fuel Cells Hydrogen Hydrogen & Aviation Fuel Hydrogen & Aviation Fuel Hydrogen & Aviation Fuel Hydrogen & Aviation Fuel Note: Aviation fuels can be Jet A or gaseous hydrogen. Table 12. Energy vectors by propulsion system and energy storage technology. Ramp Integration Batteries Fuel Cells Fixed Airport Units Electric Chargers Hydrant System Mobile Airport Units Superchargers on Truck or Trailer Tanker (Truck) Swap of Energy Containers Battery Swap Container Swap Table 13. Recharge and refueling technologies.

88 Preparing Your Airport for Electric Aircraft and Hydrogen Technologies Fixed or Mobile Chargers Many airports already supply electric power to aircraft at the gate. In particular, commercial service airports provide fixed 400 Hertz (Hz) power units connected to the grid, or air carriers and their ground handlers operate mobile GPUs. These GPUs were previously diesel-powered, but units with power packs are now available on the market. Occasionally, at small airports, aircraft may still use their APUs because the other two options may not be available. The typical GPU power recommended is 90 kW for narrow-body aircraft and 180 to 360 kW for wide-body aircraft. Aircraft battery chargers for small commuter aircraft and hybrid regional aircraft might be provided at the gate in a similar way. With these requirements in mind, it is likely that current gate facilities for conventionally powered aircraft of similar size will be suitable with minimal modification—namely, the installation of additional electric power capacity for charging air- craft batteries. Conventional aircraft will share the same gate facilities and GSE as their electric counterparts. General aviation facilities could elect to equip part of their aircraft stand with chargers. High-density tie-down parking layouts could be supplied with, for instance, built-in or low-clearance pop-up chargers that can fit between existing tie-down positions. Airport-owned hangars could be equipped as well. Coordination might be required with tenants to anticipate the growth of the electric demand. Commercial aircraft operations—including commuter, light air cargo, and regional airliner- sized aircraft—will require the installation of more powerful charging systems. Maintaining the current pace of ground operations after the introduction of electric aircraft will be a necessity. Any significant increase in the turnaround time will reduce the financial advantage of electric aviation for flight operators and negatively affect gate capacity. While general aviation, commuter, and regional aircraft might not need to recharge their batteries entirely at each stop due to the nature of their operations (short-haul flights), a quick turnaround could be achieved by using high-powered fast chargers. Current charging tech- nology is limited to about 600 kW, which is on the lower end of the estimated requirements for commercial airliners expected in the longer term (hybrid regional aircraft), which range from 600 kW to 7 MW. Battery Swap Changing batteries at the gate or stand might address the adverse impact of battery charging cycles on the turnaround time. Battery swap operations at individual airports require the following: • Equipment and trained personnel to load and unload batteries from the aircraft; • An inventory of batteries that is compatible with the aviation activity and aircraft fleet; • An infrastructure to store and charge batteries. Battery swap can help de-peak electric demand at the aviation peak hour as long as the ground handlers and FBOs have an adequate inventory of fully charged batteries. Under these condi- tions, batteries can share the power supply with other resources and be charged when these other needs are low through smart power management. Note: The future of battery swap as a way to provide fully charged batteries to an aircraft during regular operations will depend on FAA approval. If the FAA does not consider this as a minor alteration per 14 CFR 21.93, the battery swap might have to be performed by licensed mechanics instead of trained ground handlers, which may impact the operational viability and business model of this solution.

Airside Requirements 89   8.3 Hydrogen Infrastructure Emergence of Hydrogen as an Aviation Fuel Hydrogen is another promising energy vector for electric aviation, especially for larger air- craft. The advantage of H2 is its high-energy density or the electrical energy potential of hydrogen processed by fuel cells compared to its weight. In comparison, the energy found in 1 kg of hydrogen equates to that found in 3 kg of jet fuel (kerosene). However, no adequate infrastructure today delivers large quantities of hydrogen from the production sites to the aircraft. In the short term, the gas could be loaded into aircraft with fueling trucks or in special containers. For instance, Universal Hydrogen is developing an aviation-specific offer where it would play the role of broker between hydrogen producers and aviation users and organize the logistics using special containers that can be safely transported by road and loaded into aircraft. At the very long-term horizon, hydrogen pipelines could emerge at hub airports, and perhaps hydrogen hydrant systems on the airside at large-hub airports, especially if hydrogen becomes a popular energy vector for other transportation modes. Table 14 shows some of the properties of hydrogen that makes it hazardous. Current Hydrogen Aircraft Developments Currently, the aviation industry is moving toward a greener environment. Some companies have engineered aircraft that use hydrogen fuel cells, and more prototypes are being devel- oped. Table 15 provides a list of existing and prototype hydrogen fuel-based aircraft (including non-electric aircraft concepts burning hydrogen as a fuel in hydrogen jet engines yet to be developed). Hazard Type Description Physical properties leading to safety concerns • Lighter than air • Highly diffusive • Flow-induced static charge generation • Low viscosity (leaks easily) • Odorless, colorless gas Pressure • High-pressure storage, a 2,000 pound per square inch gauge (psig), or 138 bar, and above, can result in pressure rupture, flying debris • Pipe whip concern with leak events • Oxygen displacement in confined spaces • Gas jet impingement damage is possible • Gas jet impingement on personnel is also a hazard; high pressure can cut bare skin Chemical • Flammable, with nonluminous flame, no toxic combustion products • Explosive, 4% to 74% by volume, candeflagrate (typically only a modest overpressure, a few psi in open areas), can also detonate (high overpressure shock wave, several atmospheres) • Low ignition energy, 0.02 to 1 megajoule spark to ignite a deflagration • Modest autoignition temperature, 574°C (1,065.2°F) Temperature • Could be stored at room temperature, not an issue Materials issues • Embrittlement of metal • Embrittlement of plastics Toxicological • Asphyxiation in confined spaces • No other toxic concerns Source: Safety Issues with Hydrogen as a Vehicle Fuel, Idaho National Engineering and Environmental Laboratory (INEEL), 1999. Table 14. Chemical and physical properties.

90 Preparing Your Airport for Electric Aircraft and Hydrogen Technologies Hydrogen Production Hydrogen can be produced from different energy resources such as solar, wind, and nuclear, using raw materials such as water, natural, gas, and coal. Table 16 shows different hydrogen production processes with their corresponding energy source, feed stock, and cost of production. The on-site production of aviation hydrogen might be relevant in some cases, including at small and remote airports. In the Netherlands, Groningen Airport Eelde has built a 21.9 MW solar farm with the plan to produce hydrogen by electrolysis for landside and airside applications. Hydrogen Transportation There are two main ways to transport hydrogen, via truck and pipelines. Hydrogen Transportation via Trucks Because gaseous hydrogen is usually produced at low pressures (between 20–30 bars), for it to be transported, the gas must be further compressed and stored in a tank or small containers (Figure 44). The usual method is by stacking filled high-pressure cylinders in tube trailers to be hauled by trucks. There are four main types of high-pressure gaseous storage containers or cylinders: • Type I: All-metal cylinder. • Type II: Load-bearing metal liner hoop wrapped with resin-impregnated continuous filament. • Type III: Non-load-bearing metal liner axial and hoop wrapped with resin-impregnated con- tinuous filament. • Type IV: Non-load bearing, non-metal liner axial and hoop wrapped with resin-impregnated continuous filament. Aircraft Year Power Description StorageSystem Range (km) Status HY4 2015 Hydrogen Fuel Cells and Electric Batteries Four-seat fixed-wing aircraft, single propeller, twin fuselage Gas 1,000 Flown HES Element One 2018 Hydrogen Fuel Cells Four-seat fixed-wing aircraft, 14 propellers Gas / Liquid 500– 5,000 Under Development Alaka’I Skai 2019 Hydrogen Fuel Cells Five-seat futuristic “air taxi” rotorcraft, six rotors Liquid 640 Apusi i-2 2019 Hydrogen Fuel Cells Four-seat fixed-wing aircraft, two propellers Gas 1,000 NASA CHEETA 2019 Hydrogen Fuel Cells Blended wing-body large commercial aircraft Liquid n/a Pipistrel E- STOL 2019 Hydrogen Fuel Cells 19 seats, fixed-wing aircraft n/a n/a ZeroAvia 2019 Hydrogen Fuel Cells 10–20 seats fixed-wing aircraft, two propellers Gas 800 Airbus Cryoplane 2003 Hydrogen Combustion Large commercial aircraft Liquid n/a Feasibility Study or Aircraft Concept Only NASA Concept B 2004 Hydrogen Fuel Cells Blended wing-body large commercial aircraft Liquid 6,500 Airbus ZEROe 2020 Hydrogen Combustion Large commercial aircraft Liquid n/a Source: Roland Berger, Hydrogen, A Future Fuel for Aviation, 2020. Table 15. Current hydrogen aircraft developments.

Airside Requirements 91   Process Energy Source Feed Stock Capital Cost )($ million a Hydrogen Cost ($/kg) Steam methane reforming (SMR) with Combined Charging System (CCS) Standard fossil fuels Natural gas 226.4 2.27 SMR without CCS Standard fossil fuels Natural gas 180.7 2.08 CC with CCS Standard fossil fuels Coal 545.6 1.63 CG without CCS Standard fossil fuels Coal 435.9 1.34 Autothermal reforming (ATR) of methane with CCS Standard fossil fuels Natural gas 183.8 1.48 Methane pyrolysis Internally generated steam Natural gas – 1.59–1.70 Biomass pyrolysis Internally generated steam Woody biomass 53.4–3.1 1.25–2.20 Biomass gasification Internally generated steam Woody biomass 149.3–6.4 1.77–2.05 Direct bio- photolysis Solar Water + algae 50 $/m 2 2.13 Indirect bio- photolysis Solar Water + algae 135 $/m 2 1.42 Dark fermentation – Organic biomass – 2.57 Photo- fermentation Solar Organic biomass – 2.83 Solar photovoltaic (PV) electrolysis Solar Water 12–54.5 5.78–23.27 Solar thermal electrolysis Solar Water 421–22.1 5.10–10.49 Wind electrolysis Wind Water 504.8–499.6 5.89–6.03 Nuclear electrolysis Nuclear Water – 4.15–7.00 Nuclear thermolysis Nuclear Water 39.6–2107.6 2.17–2.63 Solar thermolysis Solar Water 5.7–16 7.98–8.40 Photo-electrolysis Solar Water – 10.36 aCapital costs are the expenses used to purchase and maintain fixed assets such as buildings where the hydrogen will be produced and associated equipment. Table 16. Existing and emerging hydrogen production methods. Note: TPRD = thermal pressure relief device. Source: U.S. Department of Energy, 2020. Figure 44. High pressure hydrogen container.

92 Preparing Your Airport for Electric Aircraft and Hydrogen Technologies e Type I containers are the most common, whereas the Type III and IV are more expensive. Transporting compressed hydrogen gas in high-pressure tube trailers is expensive and used primarily for distances of 200 miles (322 km) or less. Hydrogen Pipelines Transporting hydrogen through pipelines is similar to how natural gas is transported cur- rently. In the United States, there are approximately 1,600 miles of pipelines for hydrogen dis- tribution. Transporting or distributing gaseous hydrogen through pipelines is common for long distance and high-volume transport because it is less costly compared to transportation via truck. According to the U.S. Department of Energy, some of the concerns with hydrogen pipe- line distribution are: • e potential for hydrogen to embrittle the pipeline materials. • e need to control hydrogen permeation and leaks. • e need for lower cost, more reliable, and more durable hydrogen compression technology. On-Airport Hydrogen Storage Hydrogen can be distributed to airports in dierent ways, including (1) delivery of special containers for direct loading into aircra, (2) delivery via trucks or pipeline to large tank to rell empty special containers, or (3) fueling trucks. Figure 45 shows the ways in which hydrogen can be delivered. Harvard Environment, Health, and Safety Department developed a hydrogen fact sheet that lists some of the safety precautions to take when storing hydrogen. It states that, to store pres- surized hydrogen containers: • Store the containers with adequate ventilation in warehouse. • Maintain temperature of the warehouse that does not exceed 125°F (52°C). • Secure hydrogen containers and tanks to prevent falling or being knocked over. • Use ash arrestor on tanks. • Store full and empty cylinders separately. • Equip building with an automatic sprinkler or deluge system in case of re. Ways to deliver H2 to airports H2 delivered in tank for truck fueling use H2 delivered in tank to refill empty containers at airport H2 warehouse H2 delivered in small containers Figure 45. Hydrogen delivery.

Airside Requirements 93   Hydrogen Delivery to Aircraft Because of the preliminary stage of the development of hydrogen-fueled aircraft, under- standing of the amount of hydrogen needed to fuel different aircraft sizes, fuel tank capacities, and methods of fueling are not definite. Taking hydrogen fueling methods into consideration, hydrogen aircraft can be fueled three ways: • Container Swapping: Empty containers in aircraft are taken out and replaced by filled containers. • Fueling Trucks: Similar to current aircraft fueling methods, a fueling truck filled with hydrogen refills the empty tanks in the aircraft through a fueling port. • Hydrant System: This method is similar to that of current aircraft fueling through an aviation fuel hydrant system situated underneath the apron. A hydrogen hydrant system is currently not pertinent because the concept of hydrogen-fueled aircraft is in its early stages. Further hydrogen implementation, as part of a broader hydrogen economy and/or in the context of the introduction of larger hydrogen-powered aircraft, could make such infrastructure inter- esting for the busiest airports. Note: The future of hydrogen container swap as a way to provide fully loaded containers to an aircraft during regular operations will depend on FAA approval. If the FAA does not consider this as a minor alteration per 14 CFR 21.93, the container swap might have to be performed by licensed mechanics instead of trained ground handlers, which may impact the operational viability and business model of this solution. 8.4 Developing Airside Requirements General Approach Airport planners will have to determine the given planning period’s design level of demand, which is the maximum number of aircraft that should be provided with charging or refueling equipment at the same time. Figures 46 and 47 detail the processes to charge and swap batteries. Figures 48 and 49 detail the swap and refill H2 processes. The following parameters should be determined for airport planning purposes for each milestone of the planning period (typically 5 years, 10 years, and 20 years for a master plan): • Estimate or project the stimulated demand due to electric aircraft. • Expected percentage of electric or hybrid aircraft as part of aircraft fleet. • Design aircraft for electric demand. There might be more than one design aircraft, depending on the fleet mix and specialization of aviation facilities (e.g., regional terminal or ramp). • Design demand levels per category of users. • Expected number of based general aviation aircraft to be charged in hangars. • Maximum number of transient general aviation aircraft to be charged on stands. • Peak gate or stand demands for commuter and larger electric aircraft accommodated on a remote stand or “non-contact” gates. • Number of aircraft gates or stands and hangars to be equipped with chargers or serviced by charging or refueling equipment. • Requirements will vary across time with the variation of the aircraft traffic, but first and fore- most, with the growth of electric planes among the overall aircraft fleet. Impact on the Airport Electric Demand Specific considerations on airport power infrastructure will greatly vary between airports based on size, current power capabilities, and the density of the expected electric aircraft traffic.

Figure 46. Fixed electric aircraft charger electricity supply.

Airside Requirements 95   Figure 47. Battery swap and mobile supercharging process. When planning for electric aircraft, airport planners should consider the effects on power for both current airport operations and long-term airport master plans. For the individual airport, the primary impact will stem from the increased electrical demand necessary to charge electric aircraft. The effects and necessary considerations will vary between airports of various sizes based on the type and density of traffic. During the planning process, along with the aviation facility requirements, aircraft-specific power supply requirements should be developed. Based on individual charging requirements, and assuming that future chargers will take 45 minutes for a full-charging cycle, the demand could grow to several megawatts even at small airports. Smaller all-electric general aviation aircraft can be charged in about 45 minutes with 40 to 60 kW chargers. Twenty of those aircraft charging simultaneously would have an electric demand of about 1 MW (800 to 1,200 kW). Small commuter aircraft demand an additional order of magnitude. An individual aircraft might need 400 to 600 kW for ensuring charging times compatible with the typical aircraft turnaround time. At busy regional airports, power requirements might reach about 10 MW. Larger commercial aircraft able to fly medium-haul routes with all-electric or hybrid systems might demand 1 to 10 MW chargers. While such estimates are still speculative, we can reason- ably predict a power consumption of 10 to 100 MW at commercial service airports specifically for charging aircraft—assuming that 100 percent of the fleet becomes electric. Currently, terminals consume 60 percent of the electricity at a typical airport, and airfields consume the remaining 40 percent. This balance could be significantly shifted with the emer- gence of electric aircraft, especially beyond the 2030 horizon. A hub airport like Pittsburgh International Airport has a peak-power demand of 14 MW. In 2019, the airport became one of the first hub airports to have a microgrid, a system that combines a natural-gas generator and solar panels and can deliver 22.5 MW. The electric demand from aircraft charging their batteries or remote battery chargers (for battery swap) would become significant very quickly, especially when commuter and regional aircraft start flying. This aircraft-specific demand should be considered by planners in the context of

Figure 48. H2 container swap and tank refilling process from off-airport production unit.

Figure 49. H2 container swap and tank refilling process from on-airport production unit.

98 Preparing Your Airport for Electric Aircraft and Hydrogen Technologies overall growth in electric demand at airports (see Table 17). For instance, as electric cars grow in popularity, airports could seek to expand their on-site charging capabilities, further increasing power demand. The implementation of new parking technologies—such as the deployment of robotic valets at airports—would be an additional power consideration for garage and parking facilities. Trends toward reducing operational emissions have led many airports to install ground-power systems that connect directly to the airport power grid, replacing diesel-powered GPUs and aircraft APUs. Additionally, airports have centralized electrically powered precon- ditioned air units, which further reduces the need for aircraft to generate power onboard. This growth in gate facility electrification, compounded with the introduction of aircraft charging, could strain existing airport electrical infrastructure. Airport electric infrastructure is likely to be affected by the integration of electric aviation into existing airport ecosystems. Increasing electrification across airport technology and infra- structure, coupled with the introduction of high-power fast charging for electric aircraft, could place a significant strain on existing airport power grids. Two basic scenarios are likely to arise as airports seek to integrate electric aircraft into their operations: • In the first scenario, adding necessary airside equipment to support electric aircraft would not require the airport to upgrade its main electrical connection to the greater power grid. In this scenario, infrastructure modifications would require installation of charging stations and associated power distribution and management systems. • In the second scenario, the airport’s electrical supply would be insufficient to support the added equipment necessary to support electric aircraft operations. The following options would address this situation: – Smart power management at the airport to share the available capacity with other resources, which would include sharing existing power supply with other airside equipment (e.g., jet bridges) and defining prioritization rules. – Working with energy providers to upgrade their electrical power supply. – Developing local electric production at the airport, which could include a microgrid strategy to increase resiliency. Configuration Mission Baseline Aircraft Capacity Power Requirements (Assuming 45 Minutes Recharge) 1 5 10 20 50 Small All- Electric Tube & Wing Flight Training, Private, Recreational Pipistrel Alpha Electro 1 pilot + 1 passenger 20 kW 100 kW 200 kW 400 kW 1 MW Small All- Electric Tube & Wing Very Short Range (420 miles) Short Range (700 miles) 1 pilot + 3 passengers 60 kW 300 kW 600 kW 1.2 MW 3 MW All-Electric Tube & Wing Commuter Short Range (650 miles) Eviation Alice 2 pilots + 9 passengers 400 kW 2 MW 4 MW 8 MW 20 MW Hybrid-Electric Tube & Wing Regional Short Range (700 miles) UTC Project 804 2 pilots + 39 passengers 600 kW 3 MW 6 MW 12 MW 30 MW Note: These figures are for aircraft charging at the aircraft gate or stand. Required power might be lower for remote charging for battery swap. Table 17. Power requirements per number of aircraft charging simultaneously.

Airside Requirements 99   Solar power presents a viable option for airports because they can provide significant amount of space needed for large-scale solar power generation. Several U.S. airports (e.g., Indianapolis International Airport and the Denver International Airport) have leased land to developers to install solar farms on airport property, while some smaller airports (e.g., Chattanooga Metropolitan Airport) have identified solar power as an avenue to electrical self- sufficiency. Installation of solar panels could present a planning challenge for some airports because they must be situated in such a way that ensures installations do not create glint or glare conditions. Additionally, they could be unsuitable in areas that experience heavy cloud cover for much of the year. Many airports are taking a second approach to on-site power generation by installing microgrid infrastructure. These self-sufficient energy systems can allow an airport to operate independently of the main grid. Additionally, if one microgrid goes down, others can provide backup power to maintain airport operations. Many major airports have installed or are plan- ning to install microgrid systems in an effort to prevent occurrences such as the 11-hour power outage at ATL in 2017. These systems typically leverage natural gas generators as the primary power source, with some utilizing supplemental solar panels. Each of these avenues to increasing airport power supplies presents benefits and draw- backs, and airport planners must assess the impacts against the needs of their individual airport. Upgrading existing grid connections could present a more affordable short-term solution for smaller airports. However, electric aviation will further increase an airport’s reliance on electricity supplies, increasing the impact of power outages. Installing on-site power generation could greatly increase the resiliency of airport power infrastructure; how- ever, these projects would likely have higher upfront costs and longer realization of return on investment and could strain relations with existing local energy partners. Whichever path airport planners deem best for their facilities, energy providers must be involved early in the planning process. 8.5 Applicable Technical Standards and Guidance Table 18 provides a selection of technical standards applicable to electric aircraft airside facility planning and design that should be taken into consideration when developing airside requirements and alternatives. Because the electric aviation is still emerging, these publications do not address specifically e-aircraft. However, they provide standards that might apply to or be considered for electric aircraft facilities.

100 Preparing Your Airport for Electric Aircraft and Hydrogen Technologies Institution Standard Comments FAA AC 150/5300-13A and -13B (Draft) – Airport Design This document features the FAA airfield design standards. Draft AC 150/5300-13B introduces significant changes to the standards. The final version - 13B might be released in 2021. NFPA NFPA 2 – Hydrogen Technologies Code This code provides fundamental safeguards for the generation, installation, storage, piping, use, and handling of hydrogen in compressed gas (gaseous hydrogen, or GH2) form or cryogenic liquid (liquid hydrogen, or LH2) form. NFPA 55 – Compressed Gases and Cryogenic Fluids Code NFPA 55 facilitates protection from physiological, over- pressurization, explosive, and flammability hazards associated with compressed gases and cryogenic fluids. It includes standards from the former NFPA 50A and 50B standards on hydrogen systems at consumer sites. NFPA 407 – Standard for Aircraft Fuel Servicing This standard outlines vital safety provisions for procedures, equipment, and installations to protect people, aircraft, and other property during ground fuel servicing of aircraft using liquid petroleum fuels. NFPA 440 – Guide for Aircraft Rescue and Firefighting Operations and Airport/Community Emergency Planning As of March 2021, NFPA 440 is a proposed standard that is in a custom cycle due to the Emergency Response and Responder Safety Document Consolidation Plan as approved by the NFPA Standards Council. As part of the consolidation plan, NFPA 440 is combining NFPA 402 and NFPA 424 standards. NFPA 460 – Standard for Aircraft Rescue and Firefighting Services at Airports, Recurring Proficiency of Airport Fire Fighters, and Evaluating Aircraft Rescue and Firefighting Foam Equipment As of March 2021, NFPA 460 is a proposed standard that is in a custom cycle due to the Emergency Response and Responder Safety Document Consolidation Plan as approved by the NFPA Standards Council. As part of the consolidation plan, NFPA 460 is combining NFPA 403, NFPA 405, and NFPA 412 standards. SAE International AIR7765 – Considerations for Hydrogen Fuel Cells in Airborne Applications The scope of this joint European Organization for Civil Aviation Equipment (EUROCAE)/SAE International report is to compile the considerations relating to airborne application of hydrogen fuel cells. This document provides a comprehensive analysis of the use of hydrogen as a fuel by describing its existing applications and the experience gained by exploiting fuel cells in sectors other than aviation. Table 18. Main technical standards applicable to electric aircraft airside facility planning and design.