The aviation industry stands at the forefront of addressing climate change, striving to meet ambitious carbon neutrality goals by 2050. A critical element in this transformation is the adoption of Sustainable Aviation Fuel (SAF), a cleaner alternative to conventional jet fuel. Over the years, flight and ground tests using both blended and unblended SAF have demonstrated its potential to reshape aviation’s environmental footprint. One major player, Airbus, along with other carriers and manufacturers, is leading the charge. These candidates are showcasing groundbreaking campaigns highlighting SAF’s viability in reducing CO2 emissions and other environmental impacts.
Figure 1: Airbus: A320 and A350 Pave the Way
Airbus has been a key pioneer in SAF testing, leveraging its A320 and A350 aircraft (See Figure 1). In particular, the A350 has become a symbol of innovation in sustainable aviation. In the ECLIF3 (1) study, conducted in collaboration with Rolls-Royce, the German Aerospace Center (DLR), and SAF producer Neste, an A350 powered by Rolls-Royce Trent XWB engines operated on 100% unblended SAF. The study revealed significant reductions in soot particle emissions and contrail ice crystals, critical factors in non-CO2 climate effects.
These results, achieved during ground and in-flight tests, demonstrated a 56% reduction in contrail ice crystal formation compared to conventional Jet A-1 fuel. Global climate model simulations estimated that using unblended SAF could reduce contrails’ climate impact by at least 26%. The A320, with its versatility and widespread use, has also undergone a significant series of SAF tests, proving its adaptability to blended fuel scenarios. These campaigns underscore Airbus’s commitment to decarbonizing aviation and advancing towards net-zero emissions.
Figure 2: Emirates and the Boeing 777-300ER, A Milestone in Commercial Aviation
In January 2023, Emirates conducted a milestone flight using a Boeing 777-300ER powered entirely by unblended SAF in one engine (see Figure 2). This test flight demonstrated the feasibility of SAF in large, long-haul aircraft, showcasing its performance and safety in real-world conditions. The airline’s initiative is part of its broader strategy to incorporate SAF into its operations, supporting the industry’s transition to greener energy solutions.
While current ASTM standards limit SAF blending to 50% with conventional jet fuel, Emirates’ flight provided critical data for advancing regulations and proving engines’ capabilities to operate on higher SAF blends. The airline’s efforts highlight the importance of collaborative industry partnerships and regulatory advancements to scale SAF adoption.
Figure 3: ATR 72-600: Regional Aviation Takes a Leap Forward
The ATR 72-600 (Figure 3), celebrated for its efficiency and low CO2 emissions, has also played a crucial role in SAF testing. Designed for regional connectivity, the ATR 72-600 has undergone prototype test flights using SAF to demonstrate its potential in sustainably serving remote and challenging destinations. The aircraft’s ability to operate on short, narrow, and even unpaved runways makes it a vital player in ensuring greener connectivity for underserved communities.
With SAF’s ability to reduce lifecycle CO2 emissions by more than 70%, the ATR 72-600 serves as a model for how regional aviation can contribute to the industry’s sustainability goals. The ATR 72-600 sets benchmarks for future regional air travel advancements by pairing its inherent efficiency with SAF.
Overcoming Challenges in SAF Deployment
While the benefits of SAF are undeniable, the path to widespread adoption remains complex. Current SAF production technologies yield fuels with varying chemical compositions, necessitating rigorous testing to ensure compatibility with existing engines and infrastructure. Unblended SAF, such as HEFA-SPK (Hydroprocessed Esters and Fatty Acids Synthetic Paraffinic Kerosene), lacks the aromatic compounds found in conventional jet fuels, which are crucial for seal compatibility in legacy aircraft (3). As a result, modifications to engines and fuel systems are often required.
Moreover, the production and distribution of SAF are still in their infancy (Figure 4). With SAF representing less than 0.1% of global jet fuel usage, scaling production is essential. Collaborative efforts, like the Virgin Atlantic-led consortium’s successful transatlantic flight using 100% SAF, demonstrate the potential (and necessity) of coordinated industry initiatives to accelerate progress.
Figure 4: SAF -Sustainability Roadmap
The Road Ahead: Toward 100% SAF
With the benefits of ongoing research and advancements in production technologies, achieving 100% SAF certification under ASTM standards is within reach. Airbus and Boeing, for example, have both pledged to deliver aircraft compatible with 100% SAF by 2030. Additionally, initiatives like the ECLIF3 study and the Gulfstream G700’s ground emissions tests are pushing the boundaries of what’s possible.
Figure 5: Aviation’s Decarbonization Pathway
In the short term, blended SAF offers a practical solution, seamlessly integrating with existing fuel systems to reduce aviation’s carbon footprint. Long-term goals, however, hinge on the industry’s ability to address infrastructure challenges and scale production to meet demand.
Figure 5 provides a mapping of Airbus’ vision for aviation’s decarbonization pathway.
A Sustainable Takeoff
The journey toward sustainable aviation is gaining momentum, with flight and ground tests of SAF paving the way. The success of campaigns involving the Airbus A320 and A350, Emirates’ Boeing 777-300ER, and the ATR 72-600 prototype underscores the industry’s potential to transition to greener skies. While challenges remain, the dedication of manufacturers, airlines, and regulators offers hope that sustainable aviation will soon become a reality.
As SAF proves its worth, the dream of decarbonizing aviation is no longer a distant horizon but an achievable destination.
Relevance to IATA
The IATA Aircraft Technology Net Zero Roadmap has a considerable section dealing with Sustainable Aviation Fuels (SAF). These ideas are all part of mapping how aerospace will change to reduce its carbon footprint on the way to 2050.
Our web stories on this matter are delving into the second phase of that report, which covers SAF.
Figure 6, which follows, shows the first four elements of the SAF and hydrogen aircraft – Aircraft Technology Roadmap.
For this posting, we are covering Item 4 only. Noted is that on the second column, these TRM (Technology Road Map) items are indicated to have a “Before 2023” timeline.
Figure 6: The Aircraft Technology Net Zero Roadmap -SAF and Hydrogen
This is the last storyline (i.e. #4) from the “Before 2023) Aircraft Technology NetZero Roadmap. Our series will continue on other IATA TRM aviation fuel challenges and progress made
References:
- https://www.greenairnews.com/?p=5824
- https://www.atr-aircraft.com/aircraft-services/aircraft-family/atr-72-600/
- https://www.greenairnews.com/?p=2460#:~:text=Aromatics%20in%20jet%20fuel%20are%20needed%20for,consideration%20for%20SAF%20certification%20and%20blending%20limits.