Biofuels offer more than an alternative to hydrocarbons; they also reduce jet-engine particle emissions by as much as 70 percent, research by a NASA-led group suggests.

Working with the German Aerospace Center (DLR) and the National Research Council of Canada (NRCC), NASA analyzed data on the effects alternative fuels have on several phenomena, including contrail formation. Contrails, and the cirrus clouds they help create, are believed to be a factor in influencing the environment. One of the principal drivers of contrail formation is soot emissions.

Trials were conducted by flying three aircraft behind NASA's DC-8 testbed burning a 50/50 blend of aviation fuel and an alternative made from camelina plant oil. The data-collecting aircraft—a DLR Dassault Falcon 20, an NRCC Canadair CT-133, and a NASA Dassault HU-25C (Falcon 20G)—trailed the DC-8, sampling ice particles and monitoring contrail formation. Among the findings: biofuels emit less soot, which leads to a 50- to 70-percent reduction in particle emissions.

"This was the first time we have quantified the amount of soot particles emitted by jet engines while burning a 50/50 blend of biofuel in flight," said Rich Moore, NASA’s deputy project scientist and lead author of a report on the trials published in the journal Nature.

NASA plans to demonstrate biofuel benefits as part of its proposed X-plane program.