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Environment and Sustainability

The Role of Airports in Reducing Aviation’s Carbon Emissions

Oct 17, 2024

estimated  mn.

Commitments have been established to achieve Net Zero carbon emissions for operations within an airport’s control by 2050.  However, what strategic actions can airports take today that will accelerate the reduction of carbon emission beyond their control? 

Initiatives have been long in place for the reduction of greenhouse gases (GHG). The ACI Airports Carbon Accreditation program for instance includes guidance on reducing Scope 1, Scope 2, and Scope 3, emissions. Airports at Level 5 need to demonstrate that they have reduced their Scope 1 and 2 CO2e absolute emissions by ≥90% and that any residual emissions have been addressed using approved offset removals. Additionally, Level 5 accreditation requirements ask to commit to Net Zero in Scope 3 by 2050 or sooner, aligned to ISO Net Zero and/or sector Net Zero frameworks or commitments, where applicable. 

As focus increasingly turns to the reduction of Scope 3 emission, with a pinpoint on the CO2 emissions from airport aircraft, Cirium focuses on three areas where airports can help reduce the latter. 

Fleet analysis: Airports should analyze the aircraft fleet operating at their facilities to identify opportunities for using newer, more efficient models. This data can influence discussions with airlines about future aircraft selection.  

Taxiing strategies: Airports should evaluate the impact of engine taxiing and reducing taxi times can help reduce CO₂ emissions at the airport. By analyzing single engine taxiing data, airports can develop and implement taxiing strategies that can reduce emissions.

Full flight emissions: Airports should consider the full flight emissions, either calculated as “one-way full flight” (origin to destination) or as “half-distance return flight” (origin to half distance plus half-distance back to airport). Airports should also consider the Landing and Take-off (LTO) cycle.

Latest generation aircraft and reducing airport CO₂ emissions

Using Cirium’s EmeraldSkyTM flight emissions methodology, analyses indicate that employing new generation aircraft can significantly reduce airport carbon emissions compared to older models. 

For example, Adolfo Suárez Madrid-Barajas Airport (MAD) has set a new environmental benchmark for major European hubs, achieving a remarkable double-digit percentage reduction in CO₂ emissions per available seat kilometer over the past five years. This achievement, driven by a strategic shift to the latest generation of aircraft, highlights how airports can effectively collaborate with airlines and other industry stakeholders to promote the use of more sustainable aircraft.

The analysis shows an estimated CO₂ per Available Seat Kilometer (ASK) on average of just under 73g for flights departing MAD during the first quarter of 2024, which was 10.2% lower than the comparable pre-pandemic period in 2019. This was approximately twice the average improvement seen at Europe’s largest 20 airports.

A key factor in MAD’s reduction was the complete phasing out of Airbus A340-600 widebody quad jets, which in Q1 2019 had been responsible for just over 290,000t of CO₂ emissions across nearly 1,000 departing flights.

Meanwhile services using latest-generation widebody twins such as the A350-900 and Boeing 787-9 were dramatically ramped up, from a combined total of around 1,200 for the three-month period five years ago to approaching 4,000 in Q1 2024.

On the single-aisle side there were fewer than 700 A320neo departures in 2019, but more than 4,000 in the most recent quarter. The stretched A321neo and 737 Max 8, meanwhile, were completely absent five years ago but recorded over 3,200 and 1,000 departures, respectively, in the first quarter of this year.

The data illustrates how collaboration among airports, airlines, Airport Navigation Service Providers (ANSP), and other stakeholders can drive the adoption of modern aircraft technology, positively impacting emissions whether measured during full-flight departures or in the LTO cycle, which considers emissions below 3,000ft and during taxiing.

Single-engine taxiing to reduce LTO emissions

A simple, yet effective way for reducing carbon emissions during the LTO cycle is operating using half the aircraft engines on taxi in and out, meaning the reduction in CO₂ corresponds to the number of emissions that the engines not in operation would have produced.

The EmeraldSky methodology includes:

  • Flight weight estimation (true weight of the physical aircraft)
  • Flight operations (actual tracked flight time and taxi times)
  • Fuel model (per the entire flight)
  • Carbon allocation (per seat)

It is important to take all variables into consideration when calculating the actual reduction of emissions resulting from using half the engines while taxiing in and out. By conducting a thorough analysis, airports can accurately evaluate and report on the impact of different taxiing strategies.

This helps the airports determine the most effective approaches in reducing emissions associated aircraft taxiing. In addition to single engine use, reductions in taxi in and out time will also contribute to reduced emissions.

Full flight emission insights provide a complete view of airport CO₂ emissions

Although a lot of focus is placed on the LTO cycle – which is key in reducing CO₂ emissions – EmeraldSky data shows that certain aircraft factors can impact the fuel consumption during take-off while benefiting the overall emissions for the full flight duration.

For instance, modern aircraft equipped with winglets – like Boeing 737-800s and Airbus A319s or A321s – may add weight during take-off but reduce drag and create a more stable airflow during the full flight.

Cirium’s analyses show how winglets help reduce the drag by minimizing the size of the vortex where high pressure and low-pressure areas meet at the wing tip. The lower drag results in better fuel efficiency and lower carbon emissions.

Focusing on the LTO cycle limits the understanding of aircraft emissions. LTO cycles only considers emissions below 3,000ft and during taxiing. As a result, this creates a silo around aircraft emission information, whereas to reach Net Zero, we should be taking a 360-degree view of what reduces the overall aircraft carbon footprint.

Should airports therefore transition to analyzing and reporting on full flight emissions alongside the LTO cycle? Should fee structures be adapted to accommodate for the fact that airports play a pivotal role in reducing aviation’s carbon emissions and not just during take-off and landing?

Although Scope 3 emissions are not directly under an airport’s control, these emissions account for the majority of an airport’s carbon footprint, largely made of aircraft operations and passenger transport. Therefore, airport’s play a vital role in influencing their airline partners and accelerating the path to net-zero aviation emissions.

This is sponsored content. Sponsored content is provided by third parties including airports, members of ACI, World Business Partners, and others. The views expressed and/or presented by these third parties through sponsored content are their own and may not represent or reflect the views of ACI, its management, Board, or members. Readers should not act on the basis of any information contained in the blog without referring to applicable laws and regulations and/or without appropriate professional advice.

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