Contrails take up a lot of space in the daily life of François Garnier, professor in the mechanical engineering department of the École de technologie supérieure (ETS). Holder of the Safran Industrial Research Chair in the development of sustainable aeropropulsion systems, he tries to improve technologies to reduce as much as possible the formation of these white traces in the sky which have an impact on global warming and on the air quality around airports.
Posted at 11:00 a.m.
“We talk a lot about CO2 [dioxyde de carbone] when it comes to global warming, but review work done in 2021 says non-CO2such as methane, nitrogen oxides and particulates, would warm the climate twice as much as CO2 in the field of aviation,” he says.
Contrails fall into this category. But what are they, exactly? “They are the result of a physical phenomenon that only occurs when the atmosphere is humid and relatively cold,” explains François Garnier. It is the mixture of water vapor and soot particles formed mainly of carbon which are emitted by the engine and combustion in a mass of supersaturated air. Everything turns to ice in the upper atmosphere where it is -56°C. »
This “dirty ice” ends up forming cirrus clouds, these white filaments that can be observed very high in the sky.
PHOTO SARKA VANCUROVA, THE PRESS
François Garnier, holder of the Safran Industrial Research Chair in the Development of Sustainable Aeropropulsion Systems
Moreover, we can clearly see in the satellite images of busy air corridors, such as the one that connects Europe and North America, that there is a significant concentration of cirrus clouds.
François Garnier, holder of the Safran Industrial Research Chair in the Development of Sustainable Aeropropulsion Systems
These nearly transparent clouds absorb some of the Earth’s radiation and reflect it back to the ground, in addition to allowing the Sun’s rays to pass through. They therefore contribute to the increase in greenhouse gases and global warming.
The industry in preparation mode
The Safran Industrial Research Chair in the Development of Sustainable Aeropropulsion Systems began its research last year. It works, as its name suggests, with the engines of Safran, an equipment manufacturer in the aeronautics industry. The objective is to try to advance knowledge related to the physico-chemical processes involved in the formation of pollutants produced by aircraft engines and to enable Safran to better understand the relationship between internal engine components and particulate emissions. .
“We want to see how to avoid as much as possible emitting soot and also, that ice forms around these particles, explains François Garnier. It is important for the industry. To have the engines certified by the International Civil Aviation Organization (ICAO) so that they can fly, rules on pollutant emissions must be respected. For now, initial measures have been put in place to limit the emission of soot particles. There’s nothing yet on aerosols and focus contrails, but it could happen in the next few years, so be prepared. »
The Chair will work to meet this challenge over the next five years.