NASA and Boeing are collaborating to study the impact of sustainable aviation fuel on smoke formation and climate change. Their research includes flight testing different fuels and analyzing their environmental impact, contributing to NASA's goal of achieving net-zero emissions from aviation fuels by 2050.
Joint research by NASA and Boeing focuses on how sustainable aviation fuels can mitigate the environmental impact of wakes, aiming to advance greener aviation practices.
"Smoke clouds" are lines of cloud streaked across the sky by high-altitude aircraft. They are a familiar sight, but they may have an invisible effect on the Earth - trapping heat in the atmosphere. NASA researchers are working with Boeing and other partners to collect data to understand how new, greener aviation fuels can help reduce the problem.
In October, NASA partnered with Boeing to conduct a flight path study in Washington state through the company's Ecological Demonstration Program. The event focuses on generating and analyzing data on the ability of sustainable aviation fuels to benefit the environment.
Boeing's second ecoDemonstrator Explorer aircraft (737-10) performed test flights, switching between filling tanks with 100% sustainable aviation fuel or a low-sulfur version of conventional jet fuel. NASA's DC-8 aircraft - the world's largest flying science laboratory - followed suit, measuring the emissions of each fuel and the formation of smoke ice. Data collected by the DC-8's special instruments will help determine whether sustainable aviation fuels can help reduce smog formation.
"People think smoke is a major source of pollution," said Rich Moore, a research physicist for NASA's Langley Aerosol Research Group experiment and the flight's principal investigator. "With this flight, what we're trying to do is not correct smoke, but prevent smoke."
The DC-8 aircraft is based at NASA's Armstrong Flight Research Center in Edwards, California, and NASA provides other key capabilities, including a mobile laboratory for ground testing. Other partners on the flight include GE Aerospace, the German Aerospace Center, the Federal Aviation Administration, United Airlines and many other contributors.
The researchers will publish their findings within a year. "The most amazing thing about this collaboration is that the data will be publicly available to the world," Moore said.
Smoke and climate impacts
Depending on conditions and time of year, the smoke clouds can have a local cooling or warming effect, but the researchers' computer estimates suggest that globally, the smoke clouds have a greater warming effect. Over the past few years, NASA has worked with partners to match these models with observations in an effort to understand how and when smoke clouds form and their impact on the environment.
Exhaust gases from jet engines include water vapor and soot particles. When aircraft operate in low-temperature environments at high altitudes, smoke and dust are formed. After the water vapor in the exhaust cools and condenses, it interacts with smoke or other particles in the air to form ice crystals. This smoke can linger in the upper atmosphere for hours, affecting local temperatures and, over time, affecting climate change.
Alternative fuels, including sustainable aviation fuels, can release fewer soot particles. Research models found that this would result in fewer crystals, and those that formed would be larger, falling and melting in the warmer air below, reducing the environmental impact of the smoke.
In addition to this latest ecological demonstration cooperation project, NASA and the German Aerospace Center have also launched a joint flight research activity called ND-MAX. During the event, the DC-8 tested the smoke cloud left behind by a biofuel-operated A320 airliner operated by the German Aerospace Center. In 2013 and 2014, NASA led a series of research flights using small business class jets titled "Impact of Alternative Fuels on Haze and Cruise Emissions."
Over the past decade, NASA-funded research has shown that sustainable aviation fuels have significant advantages in reducing engine particulate emissions, which can affect air quality near airports and contribute to the formation of smoke clouds. Efforts to develop and evaluate sustainable aviation fuels focus on delivering the performance of conventional jet fuel without releasing new carbon dioxide into the environment. These fuels can be derived from sustainable sources such as feedstock and waste resources.
NASA's sustainable aviation fuel research is part of the agency's efforts to advance the United States' goal of net-zero greenhouse gas emissions from aviation by 2050.
Flight testing remains the gold standard for understanding aerospace innovations and their impact on the environment, making partnerships like the ecoDemonstrator and research aircraft like the NASA DC-8 an important source of data that can help make aviation more sustainable, protect the environment and improve life on Earth.