CHAPTER 3

Sustainability

This chapter addresses a variety of environmental sustainability issues that arose in the futuring workshops. The chapter includes how airports are reducing their emissions (particularly greenhouse gas emissions), becoming more energy-resilient (including using less energy), and reacting to the challenges posed by climate change. It also addresses community relations, which are often driven by conflicts over land use, noise, and pollution. It begins with the discussion of some of the issues facing airports in 2023, when the workshops were held. The chapter then discusses how changes might occur to address some of these challenges over the next few decades and ends with a discussion of how the airport of 2050 might function, along with remaining challenges that participants did not think would be resolved by 2050.

State of Sustainability in 2024

Emissions

In 2023, the aviation sector was responsible for approximately 2% of greenhouse gas (GHG) emissions in the United States (U.S. EPA, 2023a). Although only approximately 2% of aviation emissions were directly or indirectly associated with airport-owned or controlled sources, pressure had been growing for all aviation stakeholders to reduce their emissions. Environmental Protection Agency (EPA) definitions at the time divided emissions into three categories (U.S. EPA, 2023b; FAA 2023d):

• Scope 1: Emissions from sources that are owned or controlled directly by airports.
• Scope 2: Indirect emissions from airports’ “consumption of purchased energy”.
• Scope 3: Emissions that occurred on airport property but were not controlled by airport sponsors.

About 90% of aviation emissions came from domestic commercial flights, which fell under Scope 3 (see Figure 1 in FAA, 2021).

In 2021, major trade groups and companies in the aviation community—representing airlines, airports, air traffic management, and other stakeholders—adopted goals of “net zero” carbon emissions by 2050 (ATAG, 2021). The FAA also released its own Aviation Climate Action Plan adopting the same goal (FAA, 2021). Both initiatives suggested similar pathways to reach this goal: alternative fuels, new technologies, operational improvements, and some carbon offsets. For airport-specific activities that could reduce emissions, the FAA highlighted actions such as improving building insulation, purchasing renewable energy, installing renewable energy systems, reducing energy consumption, monitoring the efficiency of heating, ventilation, and cooling systems, and purchasing low- or zero-emission vehicles and ground support equipment (FAA, 2023d).

To achieve these net zero goals, airports and other stakeholders had begun to lay the groundwork for a transition to cleaner energy sources. As of 2023, aircraft still relied heavily on jet fuel and conventional aviation gasoline, and SAF met less than one tenth of 1% of global jet fuel demand (O’Malley et al., 2021). However, one unleaded aviation gasoline (avgas) had already been approved, and SAF research was well underway. On the airport side, according to a 2020 report, about 150 airports had some type of renewable energy project located on their property; the majority of these were solar (Barrett, 2020). In addition to these optimistic signs, there were also critiques that some environmental claims from the aviation community were overstated (Plucinska et al., 2023; Stankevicuite, 2023).

Energy Resilience and Electrification

Airports worked to improve their energy resilience in the face of emerging threats that had the potential to disrupt or curtail their operations. Power outages showed how many airports were vulnerable because of their reliance on the electrical grid. For example, an 11-hour outage at Hartsfield-Jackson Atlanta International Airport (ATL) in 2017 forced the cancellation of about 1200 flights at an estimated cost of $50 million. Twenty-four of 30 commercial airports experienced a combined 321 power outages over a 7-year period (GAO, 2023b). The importance of energy resilience was further heightened by the potential of electric vehicles and ground support equipment to reduce airport emissions. In 2023, airports often did not have the energy infrastructure necessary to support the transition from fossil fuels to battery-powered equipment, much less the longer-term possibility of needing to provide power to electric aircraft.

Airports were also continuing their efforts to increase energy efficiency. Energy-efficiency measures that were becoming more widespread included more efficient heating and cooling systems, and reuse of construction materials to reduce truck trips. These investments often paid for themselves in the long run through reduced energy costs.

Climate Disruptions and Response

Climate change challenged airports with more frequent and intense weather events as well as extreme heat. While it was difficult to attribute specific weather events to climate change, major disruptions from extreme weather were clearly increasing. In 2023, the United States experienced 25 disasters that each caused $1 billion or more worth of damage, the highest number ever. The majority of these were severe storms (National Centers for Environmental Information, 2024). 2023 was also the hottest year on record globally (Gramling and Ogasa, 2023), and 45 U.S. cities experienced their hottest year ever (Livingston, 2024). 2024 has continued to generate new record-high global temperatures (Younger, 2024). Many airports were already experiencing cases of operational disruptions because of extreme heat (Weise, 2022; Schlangestein, 2023).

Community Relations

The relationship between airports and their neighboring communities shifted as social expectations and environmental regulations changed. Communities near airports got involved with future plans as part of federally and locally mandated community engagement mechanisms. Communities wanted airports to commit to sustainable development, treat the local community as a partner, and take actions to mitigate noise, improve air quality, responsibly manage water discharges, and reduce the climate footprint of aviation. Airports began to understand the value of being a good neighbor, particularly regarding compatible land use and other community needs.

Initial Steps to 2030

Emissions

In the 2020s, research and initial deployment of cleaner aviation fuels was a major focus of reducing aviation emissions. The EAGLE program, an FAA-industry collaboration, came close to meeting its goal to have lead-free avgas by 2030. While an unleaded avgas compatible with most existing GA aircraft had been approved in late 2022, ramping up production to meet potential demand took considerable time. The initial cost of the new fuels was higher than conventional avgas by 60–85 cents per gallon (at a time when avgas was generally $5 to $10 per gallon). The transition to lead-free avgas continued throughout this period as GA airports retrofitted their existing fueling systems, or created a second one, and the EPA and FAA hammered out regulations (Wolfe, N., 2023).

SAF was also important because it can be used in most existing commercial service aircraft. While the use of SAF did not increase substantially until the end of the decade, the increase that did occur was driven by three main factors. First, continued research led to breakthroughs in using algae and municipal waste as viable feedstock candidates, which helped bring down the cost. Much of this work was supported by a multi-agency consortium via the “SAF Grand Challenge” (U.S. DOE et al., 2022). Second, the streamlining of ASTM certification processes was also helpful in spurring SAF development (Oakleaf et al., 2022). Finally, the ReFuelEU Aviation Initiative, a European Union regulation, required that “all fuel made available to aircraft operators at EU airports contains a progressively increasing minimum share of SAF,” increasing from 2% of aviation fuel by 2025 to 70% by 2050, and similarly encouraged increased incorporation of synthetic fuels (Soone, 2023). This initiative creates an incentive for increased SAF production. While these steps focused on aircraft, airports re-examined their fuel delivery and distribution systems to ensure that these more sustainable fuels could be made readily available as commercialization approached.

Energy Resilience and Electrification

Airports took steps to shore up the resilience of their power supplies. Starting mostly with large hub airports, major investments were made in energy resilience. These investments often took the form of power generation projects, although different airports pursued different types of investment depending on their location and available land and buildings. Some had the space to build microgrids, or self-contained grids that can operate independently or be tied into a larger grid. Solar power was the most common choice of energy source for airport microgrids, as methods for capturing energy from other common renewable energy sources such as water and wind were often not compatible with airport operations. The declining cost of battery storage during the 2020s also encouraged the use of solar panels. Still, solar energy was not a viable option for all airports, in part because of such challenges as glare, which can interfere with aircraft operations (GAO, 2023b).

One regulatory change that facilitated airports’ investments in energy infrastructure was the ability to use Airport Improvement Program (AIP) funding for a wider range of power supply projects, as provided in the FAA Reauthorization Act of 2018 (GAO, 2023b). AIP grant assurances were loosened further in the late 2020s such that airports could use AIP funding to pay for

projects that resulted in sufficient electricity generation to sell it back to their local utilities (something that was not previously allowed) (GAO, 2023b). This opened the door to more projects, increasing the importance of this revenue source while also increasing airport energy resilience.

Climate Disruptions and Response

Airports of all sizes developed climate response plans during this period. These plans focused less on reducing emissions from airports and more on adapting to climate change impacts that affect various elements of operations. Two common elements of these plans were better preparation for disruptions because of storms, and infrastructure investments that make the airport less vulnerable to a variety of climate change impacts. Some airports in areas where intense heat was projected to worsen began looking at longer runways because larger aircraft can require longer runways to take off safely at elevated temperatures.

Community Relations

These energy and climate plans often involved complex interactions with local communities, accounting for their preferences, planning efforts, and approval processes. Some airports began reaching out to or even helping establish working groups with the local community as a forum to discuss these issues.

2030–2040

Emissions

The transitions to unleaded avgas and SAF made considerable progress during this period. By the mid-2030s, this avgas transition was largely complete, although a few GA aircraft were still operating on leaded avgas, and the EAGLE initiative concluded. In terms of SAF, breakthroughs in feedstocks led to lower prices, and many airports were able to reconfigure their fueling infrastructure to support increased use of SAF. The U.S. federal government also introduced mandates for the usage of SAF, based on the European experience. While mandates were not universally popular, the industry agreed to a phased approach over a period of years as an alternative to even stricter measures supported by environmental advocates.

Hydrogen was slower to emerge as a potential alternative fuel. Unlike SAF, which is a “drop-in” fuel that does not require modifications to existing aircraft, hydrogen required new aircraft designs, and the fuel posed delivery and storage challenges to airports (Hileman, 2020). Unlike SAF, which can be used for airlines traveling long-haul flights, hydrogen fuel cell aircraft were best suited for regional flights between 30 minutes and 1.5 hours (ATAG, 2021; see Figure 4 in Oakleaf et al., 2022). While the U.S. Department of Energy (U.S. DOE) created the Hydrogen Shot program in 2021 (U.S. DOE, n.d.), its goal of reducing the cost of hydrogen to $1.00 per kilogram within a decade had not been reached. The first commercial hydrogen flight occurred in the late 2030s.

Energy Resilience and Electrification

By the late 2030s, many airports—not just large- and medium-hub, but also smaller and GA airports—had added on-site power generation, mostly microgrids powered by renewable energy

sources. These projects mitigated airports’ growing electricity costs, provided high-profile progress toward the net zero goal, and in some cases provided a modest revenue source.

Climate Disruptions and Response

Climate change continued to affect air transportation during this period. Airports across the country faced noticeable increases in severe weather events, as well as extreme heat. Intense storms became more frequent, and many occurred in locations where airports were less prepared (e.g., snowstorms in the mid-South, hurricanes on the West Coast). Airports faced with unfamiliar weather events often struggled to get back to normal operations within 4 to 5 days, which had ripple effects nationwide. Several such incidents received high-profile media attention, which spurred demands for better emergency preparations and greater investments in climate resilience.

As one consequence, airports stepped up their ability to share best practices between airports with long experience handling certain types of disruption, creating national forums that built on earlier regional efforts such as the Southeast Airports Disaster Operations Group (SEADOG, n.d.).

In terms of investments, many airports began increasing their drainage capacity to mitigate flood risk from heavy rainfall and storm surge. Another common investment was hardening infrastructure, such as airport hangers and roofs, to make them more resistant to high winds. In coastal areas where sea level rise had begun to cause sunny-day flooding regularly, airports moved critical assets away from the floodplain and created barriers such as perimeter dikes (Burbidge, 2018).

Community Relations

Climate issues spurred greater awareness, especially on the part of business communities, of the importance of air travel to a region. In some metro areas, airports formed coalitions with outside organizations to collaborate on broader campaigns to ensure airports’ continued viability. In some cases, this meant lobbying on the part of the region for increased federal and state funding. In others, the coalitions widened to involve community and environmental advocates. In other cases, federal programs such as the U.S. Global Change Research Program supported these engagements. Coalition partners did not always see eye to eye, but the program had the benefit of providing a forum to discuss issues relevant to airports.

2040–2050

Emissions

Aviation reached net-zero GHG emissions for Scope 1 and 2 emissions by 2050, delivering on the commitments made by the coalition of stakeholders and governments in the early 2020s. Scope 1 (emissions from the airport) was achieved by completing the transition of conventional ground vehicles, such as shuttles and baggage vehicles, to electric, gate electrification, and geothermal systems.

Scope 2 (emissions from purchased electricity) was achieved more quickly by airports in regions where utilities were more aggressive about transitioning to clean energy sources. But by 2050, all airports had switched the electricity they purchase to cleaner sources. Federal

decarbonization requirements incentivized continued development of renewable sources, particularly solar and wind. In a few metro areas, airports were key entities pushing utilities to increase the share of renewable electricity.

Net zero remained elusive for Scope 3 emissions (emissions that take place on airport property, including from aircraft operations), but progress has been substantial. The bulk of these reductions was achieved through the transition to SAF. By the early 2040s, SAF was on track to replace fossil fuels on most flights by 2050 (the original target agreed to in 2021). The cost of SAF had fallen, while production and distribution had ramped up accordingly. In addition, as governments of other countries passed more stringent decarbonization requirements, airlines with international operations were highly motivated to make this transition.

As 2050 neared, alternative propulsion technologies progressively replaced legacy aviation engines. These included electric propulsion systems, hydrogen-powered aircraft, and hybridized jet engines leveraging both technologies. The transition to these low-carbon energy sources required the creation of new infrastructure and supply chains dedicated to production, distribution, and storage. The GA fleet had transitioned to unleaded avgas by the early 2030s, and by 2050 the share of these aircraft that were electric continued to increase.

Other factors included operational improvements and innovation in carbon capture. With the realization of air traffic control efficiencies (as discussed in the previous chapter), excess fuel burn decreased, reducing emissions (FAA, 2021). The aviation community also championed the development of direct air capture to compensate for the residual emissions of the SAF lifecycle.

Energy Resilience and Electrification

The trend toward building on-airport microgrids continued. By the early 2040s, about two-thirds of large- and medium-hub airports had either built a microgrid, or were actively in the process of planning one. Most of these were solar-powered, and such projects were less common at small-hub and non-hub airports, mostly because of the lack of space. Airports of all sizes without the space for microgrids continued to update their electrical infrastructure in other ways, such as replacing older transformers and distribution lines, installing additional generators, and implementing programs to reduce demand during peak periods.

Funding for electricity investments at airports became more readily available. The multimodal reauthorization bill of the early 2040s, as discussed in the next chapter, created new grant funding as part of an accelerated effort to switch to cleaner energy nationwide. Excess energy was sold back to the grid, although revenue from these sales rarely constituted a large fraction of airports’ total revenue, and projects were typically sized to serve only the airport. However, the investments were still deemed important, as airports’ energy usage continued to grow. In some cases, airports intentionally invested in larger projects, thereby becoming local clean energy producers for the surrounding communities.

Climate Disruptions and Response

Despite the push for decarbonization in the United States and around the globe, climate-fueled disasters continued to increase in frequency and magnitude over this decade. For airports near coasts, sea level rise exacerbated the flooding from storms, and hurricanes and rainfall continued

to break previous records. Airports continued to face challenges in dealing with disasters that were not previously common in their region. However, some regional impacts unfolded as had been previously predicted: a two-foot sea level rise threatened infrastructure in northern California, the Gulf Coast, and the mid-Atlantic (NOAA, n.d.), while thunderstorms were projected to increase the most in the Midwest and southeast (Haberlie et al., 2022).

As a result, airports of all sizes continued to wrestle with resilience. Some had success with hardening their infrastructure, such as by increasing the capacity of drainage systems, making underground or low-lying infrastructure (like electrical cables) more water-resilient, improving building insulation, and investing in new tarmac materials (Climate ADAPT, 2023). In a few cases, major storms—ones that might previously have created severe disruptions—caused relatively little damage. Exposed airports made both airside and landside infrastructure investments to reduce exposure to storm surge and sea level rise. A handful of non-hub or GA airports closed down because of operational disruptions becoming too costly and unpredictable. Of those, some were in coastal areas where sea level rise caused frequent sunny-day flooding at high tides. Others had been more frequently exposed to extreme heat events that disrupted standard operations on a regular basis. These disruptions included aircraft having to fly with less weight, workers being unable to work outdoors without becoming sick, tarmacs melting, and the inability to cool airport buildings and aircraft on the ground to comfortable temperatures (Burbidge, 2018; Sampson and Andrade, 2023).

Community Relations

On the brighter side, many of the coalitions that formed over the past 20 years succeeded in better integrating airport priorities with community needs. Aircraft becoming both cleaner and quieter opened a door for local zoning boards to be more responsive to ensuring that land uses near airports remain compatible.

Continuing Challenges

Climate change resulted in an unprecedented frequency and intensity of severe weather events. From one perspective, airport infrastructure proved remarkably resilient, as services were often restored much more quickly than would have been feasible under previous infrastructure. However, disruptions still increased in frequency, with airports relying on mitigation strategies and infrastructure hardening.