NASA-led research prepares results on CO2 impact of aviation biofuels

US space agency NASA and European academics will in a few months release findings on the extent to which biofuels reduce pollution from aircraft.

The research is an attempt to bring some scientific clarity to the debate on how much, or indeed if, the use of alternative jet fuels (AFJ) can reduce the greenhouse effect of contrails, which are formed by vapour trails from aircraft and contribute to climate change.

The research comes as many of the world’s airlines and fuel refiners prepare to use and supply different biofuel blends that will likely be mandated by the UN’s aviation agency ICAO as part of plans to cap the sector’s emissions at 2020 levels by 2050.

Working out carbon emissions reductions from particular AFJ blends will be crucial in terms of calculations through the ICAO scheme.

For three weeks, the scientists conducted eight test flights involving two aircraft flying out of a US Air Base in Ramstein, at varied altitudes and with different levels of thrust.

An Airbus A320 was refueled with a different kerosene blend for each test flight, and was followed by a NASA's "flying laboratory" based aboard a DC 8 which took measurements from the A320’s exhaust plume.

"If we find a way to reduce the soot particles in the aircraft exhaust, the climate-warming effect could be reduced by new fuel blends," said Stephan Borrmann, a scientist at the University of Mainz who is working on the project. 

He added: “We also have the opportunity to make rare and valuable measurements of the natural ice clouds (cirrus) at this altitude, the properties and effects of which are also a key research topic."

The Mainz-based researchers expect initial results from the measurement flights from Ramstein in two months, at the earliest.