NASA, Partners Study SAF's Impact on Contrails
Contrails, those captivating streaks of clouds left behind by high-flying aircraft, are a common sight in our skies. However, their hidden impact on the environment, specifically their ability to trap heat in the atmosphere, is a growing concern.
In a collaborative effort involving NASA, Boeing, United Airlines, and various partners, researchers are actively collecting data to explore how innovative, environmentally friendly aviation fuels might mitigate this issue.
In a notable initiative during October, NASA and Boeing joined forces to conduct a contrail research campaign in the state of Washington as part of Boeing's ecoDemonstrator programme. The campaign was meticulously designed to generate and analyse data related to the potential environmental benefits of sustainable aviation fuels.
Boeing's second ecoDemonstrator Explorer aircraft, a 737-10 model, conducted a series of test flights alternating between tanks filled with 100% sustainable aviation fuel (SAF) and a low-sulfur variant of conventional jet fuel.
Following closely was NASA's DC-8 aircraft, renowned as the world's largest flying scientific laboratory. This aircraft was equipped with specialised instrumentation to measure emissions and contrail ice formation resulting from each type of fuel. The data collected by the DC-8 holds the promise of shedding light on whether sustainable aviation fuels can indeed mitigate the formation of contrails.
Rich Moore, a research physical scientist with NASA's Langley Aerosol Research Group Experiment and the principal investigator for this campaign, emphasises the importance of this effort, noting that "Contrails are believed to be a major source of pollution. With this flight campaign, we're looking not so much at correcting contrails but at preventing them."
In addition to the DC-8, stationed at NASA's Armstrong Flight Research Center in Edwards, California, the agency brought additional crucial assets to the project, including a mobile laboratory for ground testing. The collaborative effort also involved various partners such as GE Aerospace, the German Aerospace Center, the Federal Aviation Administration, and numerous other contributors.
The exciting aspect of this partnership is the commitment to public transparency. Within a year, the researchers intend to make their findings accessible to the world, fostering greater awareness and understanding of this critical issue.
Contrail clouds have the potential to either cool or warm localised areas, contingent on specific conditions and timing. However, computer models suggest that, on a global scale, their warming effect outweighs their cooling effects. In recent years, NASA has diligently worked with partners to reconcile these models with real-world observations, seeking a deeper comprehension of contrail formation, its timing, and its overall environmental impact.
Contrails come into existence when jet engines release water vapour and soot particles while operating at high altitudes with cold temperatures. The released water vapour cools and condenses, interacting with airborne particles, resulting in the formation of ice crystals. These contrails can linger in the upper atmosphere for hours, leading to localised temperature effects that, over time, contribute to climate change.
The promising aspect of alternative fuels, particularly sustainable aviation fuels, lies in their potential to release fewer soot particles. Research models suggest that this could lead to fewer, larger ice crystals that fall and melt in the warmer air below, ultimately reducing the environmental impact of contrails.
This recent ecoDemonstrator collaboration is not the sole effort in this endeavour. NASA and the German Aerospace Center conducted a joint flight research campaign known as ND-MAX, focused on testing contrails generated by an A320 airliner using biofuels. Furthermore, between 2013 and 2014, NASA spearheaded a series of research flight programmes involving smaller business-class jets, examining the effects of alternative fuels on contrails and cruise emissions.
Over the past decade, research funded by NASA has underscored the significant benefits of SAF in reducing engine particle emissions that can influence local air quality near airports and contribute to contrail formation. The emphasis has been on developing and evaluating these fuels to match the performance of conventional jet fuel while minimising carbon dioxide emissions. These SAFs can be derived from renewable sources like feedstocks and waste materials.
NASA's commitment to SAF research aligns with the broader goal of the United States to achieve net-zero aviation greenhouse gas emissions by 2050.
In conclusion, flight testing remains the definitive method for understanding aerospace innovations and their environmental implications. Partnerships like ecoDemonstrator, along with NASA's cutting-edge research aircraft such as the DC-8, serve as vital sources of data that can drive aviation towards greater sustainability, safeguarding the environment and enhancing the quality of life on Earth.