Emissions from aviation often result in jet trails, a specific type of cloud formation. These clouds can influence climate through alteration of water vapor and heat retention due to how they reflect radiation. Jet emissions also contain aerosol particles that can influence atmospheric behavior. Direct emissions of carbon dioxide also influence the climate. For all these reasons, governments are considering ways to curb aviation-related emissions.
Recently, a team of researchers has investigated the impact of biofuels on aviation emissions. Sustainable bio jet fuels offer a potential route to offsetting greenhouse gas emissions, but issues of cost and sustainability continue to hamper biofuels’ widespread adoption. Use of bio jet fuels also offers other advantages, including a potential reduction in harmful emissions due to near-zero levels of sulfur and aromatic chemicals common in petroleum-based jet fuels. These types of emissions are particularly problematic because they can induce further cloud formation.
Cruise condition evaluation of jet engine exhaust
The studies were conducted using NASA DC-8 turbofan engines on flights originating at NASA’s Armstrong Flight Research Center in Palmdale, California. The aircraft contained four wing-mounted engines that could be fed fuel separately. The researchers took measurements of jet engine exhaust at cruise conditions when burning either a blended biofuel or a conventional petroleum jet fuel. The petroleum jet fuels explored were either medium- or low-sulfur Jet A fuel. The biofuel was an approximately 50:50 volume blend of low-sulfur content Jet A fuel and a Camelina-based EFA biojet fuel.