According to a study published today in the journal Nature , adding biofuel from camelin oil to the conventional fuel used by aircraft reactors reduces the number and mass of volatile and non-volatile particles by 50 to 70% Issued during high altitude flights.
Biofuels are an attractive option for aviation because they contain very little or no sulfur and aromatics, unlike petroleum-based fuels.
As a result, they reduce the emissions of sulphates and soot particles by reactors, which have an impact on air quality and the formation of clouds of condensation, these typical white streaks produced by aircraft In flight in their wake.
The authors of the study remind us at the outset that these clouds of condensation affect the climate. ” Aerosol emissions from airplanes induce the formation of cirrus. These persistent clouds [resembling fine white filaments] that are scattered in the sky absorb the solar radiation, which helps to increase the temperature of the atmosphere, “ explains Anthony Brown, aerodynamics engineer at the Institute for Aerospace Research Of the National Research Council (NRC).
” When the moisture in the atmosphere is saturated, the fine particles that are released by the airplane reactors are nuclei around which the water vapor condenses. This is how condensation clouds are formed at the rear of aircraft in flight. “
Reduction of particles
In their study, researchers carried out exhaust sampling of a NASA DC-8 spinning at its full cruising speed at an altitude varying between 9,000 and 11,000 meters.
Some tanks on this aircraft were filled with conventional fuel while others contained a mixture of 50% biofuel from camelina oil and 50% petroleum-based fuel but low in sulfur.
The samples were taken from a NASA, German Aerospace Center and NRC spacecraft following NASA DC-8 at a distance of 30 to 150 meters to ensure that the gas plumes from the various reactors Being fueled by different fuels) did not have time to mix.
The researchers observed that emissions of volatile particles, such as sulphates and nitrates, and non-volatile particles, mostly soot particles (or black carbon), which resulted from the combustion of the biofuel blend, were Reduced by 50-70% compared to those from the combustion of petroleum-based fuel.
However, this reduction was somewhat less (25%) when the engines deployed their maximum thrust.
” By reducing the number of soot particles emitted, the biofuel reduces the number of condensation nuclei and hence the formation of condensation clouds, “ Brown said. “However, we have to accumulate more data because our current results have too much a standard deviation [variation around the mean value] . “
The fact that the hydrogen content of the biofuel is higher (8% higher) than that of petroleum-based fuel, however, has the disadvantage that ” the oxidation of hydrogen results in the production of a greater quantity of steam Of water which, by condensing, promotes the formation of clouds of condensation, “ explains Brown.