A new study led by Nasa has revealed that biofuel-powered aircraft engines can reduce carbon emissions by 50% to 70%.

In 2013 and 2014, Nasa conducted a series of flight tests near its Armstrong Flight Research Centre in Edwards, California, US, as part of the recently published Alternative Fuel Effects on Contrails and Cruise Emissions Study (ACCESS).

During the tests, Nasa flew its DC-8 four-engine aircraft, powered by a 50-50 blend of aviation fuel and a renewable alternative fuel of hydro processed esters and fatty acids produced from camelina plant oil, as high as 40,000ft above Earth.

Various data such as the effects of alternative fuels on engine performance, emissions and aircraft-generated contrails at altitudes flown by commercial airliners were collected from the tests.

“Soot emissions also are a major driver of contrail properties and their formation."

Three research aircraft were used to fly behind the DC-8 at distances ranging from 300ft to more than 20 miles to measure emissions and study contrail formation.

The trailing aircraft included Nasa's HU-25C Guardian jet, a Falcon 20-E5 aircraft owned by German Aerospace Center (DLR), and a CT-133 jet provided by National Research Council of Canada.

Nasa Langley Research Centre ACCESS project scientist Bruce Anderson said: “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 minimise their impact on Earth’s environment.”

The researchers involved in the ACCESS project are planning to continue their study to understand and demonstrate the potential benefits of using biofuels to power aircraft engines.

Image: Nasa's HU-25C Guardian aircraft flying 250m behind its DC-8 aircraft. Photo: courtesy of National Research Council of Canada.