Posted by Kayleigh DeMace on March 29, 2017

Are greener skies on the horizon for travelers?

Looks like it! NASA recently confirmed jet engines that use biofuels produce fewer aerosol particle emissions in their exhaust trails.

Aviation produces 2.5% of the world's carbon emissions so this can have a big impact on the environment and the airlines.

Alternative Fuel Effects on Contrails and Cruise Emissions Study (ACCESS)

According to the ACCESS study, NASA found that biofuels could cut jet emissions by 50-70%.

This study, conducted by NASA and agencies from both Germany and Canada, focused on flights during 2013 and 2014 that emitted contrails. Test flights were conducted at the Armstrong Flight Research Center in California.

The study was conducted with three research planes flying behind a DC-8 jet that used a 50/50 blend of aviation fuel and biofuel. The trailing planes included a HU-25C Guardian, a Falcon 20-E5, and a Canadair CT-133.

This is the first time soot particles have been quantified from an engine burning a 50/50 oil blend. Past ground tests showed that biofuel produces less sulfur and carbon emissions than jet fuel, but flight tests needed to be conducted because the environment is much different up there.

"Soot emissions also are a major driver of contrail properties and their formation. As a result, the observed particle reductions we've measured during ACCESS should directly translate into reduced ice crystal concentrations in contrails, which in turn should help minimize their impact on Earth's environment." Bruce Anderson, a scientist on the ACCESS project.

NASA's research took things to the next level with their in-air testing. The trailing planes tested emissions from NASA's DC-8 at three different engine thrust levels. Testing planes flew behind the plane at distances ranging from 300 ft to 20 miles to test emissions.

These contrails are created at cruising altitudes when hot exhaust mixes with cold air. Contrails contain mostly ice particles, but they also carry impurities from the burning fuel, such as carbon and sulfates. They can also induce cloud formations that would not normally be there and are believed to trap heat and warm the planet.

That's important because contrails are believed to have more of an impact on the environment than aviation carbon dioxide emissions.

Biofuel Produces Less

On top of producing fewer particles, the plane running on a biofuel blend also produced smaller particles.

Their work isn't done, though. NASA's research suggested further studies to determine whether or not the higher hydrogen content in biofuel could increase the ice crystal mass in a plane's contrails.