Biokerosin distributes the beautiful but harmful contrails in the sky
Biokerosin is not only a renewable resource for the climate. Aircraft with biofuels also emit much less soot particles.
And they have nothing to look for in airports of 10,000 m.
For there they provide for Cirruswolken, which are not good for the climate.
If the kerosene is 50 percent biofuels, the soot particle emissions of an aircraft engine are reduced by 50 to 70 percent compared to the combustion of pure kerosene.
This also greatly reduces the climate induced formation of contrails from which clouds form.
This is demonstrated by recent studies by Nasa, the German Aerospace Center (DLR) and the Canadian National Research Council (NRC).
Soot particles reinforce the formation of cirrus clouds Already in 2014 the research institutes had sent the DLR research aircraft Falcon and the Nasa research aircraft DC-8 over the USA to great heights.
In order to measure exactly how much the emission of soot particles depends on the fuel.
As a biofuel, the researchers used HEFA, which is extracted from the oil of Leindotter plants.
The CFM56 engines of the DC-8 were operated alternately with a regular Jet A1 jet and a 1.
1 mixture of Jet A1 and the biofuel HEFA. “It is the first time we have measured the number of soot particles emitted by an engine that burns biofuels,” said Nasa researcher Dr. Rich Moore, who is the main author of the new research results in the journal Nature.
The researchers flew directly behind the DC-8 and measured the soot particles and gases emitted.
“Measurements in the wake of aircraft require a lot of experience from the crew and proven measurement equipment, which DLR has built up over many years,” explains DLR Head of Mission Dr. Hans Schlager.
70% less soot particles from biofuels
The result of the measurements: The number of soot particles decreased by up to 70% at 50% of HEFA in the fuel.
For the climate are the top news. The carbon black particles in the air between 8,000 and 12,000 m are poisonous to the climate.
Ice crystals, which are visible as contrails, form around the particles.
They often stay in the sky for many hours, are blown away and form cirrus clouds at high altitudes.
As early as 2011, DLR researchers had for the first time determined that the negative effect of these clouds on the climate is significantly worse than the combustion of kerosene.
DLR researchers assume that the cirrus clouds at high altitudes hinder the heat radiation from the earth.
“Contradictory circling today has a similar climate impact as all the carbon dioxide emissions from air traffic collected over more than 100 years in the atmosphere,” says Schlager from the DLR Institute for Atmospheric Physics.
“The soot emissions largely determine the number of ice crystals in with the possibility to reduce soot emissions in engine exhaust gases.
By more than half by means of biofuels, a way opens the way to reduce the environmental impact of contrails. ”
More test flights next year
In the next step, the researchers now want to test how the composition of different alternative fuels affects the formation of soot particles and thus the formation of contrails.
The flights will take place in early 2018 in Germany.