Sustainable e-kerosene has the great advantage of burning CO₂-neutral: Only so much CO₂ comes out of the engine as was previously extracted from the atmosphere for the production of e-kerosene, if produced according to the atmosfair fairfuel standard with CO₂ originating from non-fossil residues or direct air capture.
Does this mean that we can already fly climate-neutral with green e-kerosene? Unfortunately not, because the use of e-kerosene in jet turbines also leads to a number of other climate effects similar to fossil kerosene. These include in particular the formation of contrails and ozone at high altitudes, collectively known as “non-CO₂ effects”. These actually warm the climate twice as much as the pure CO₂ from the kerosene.
This paper presents how e-kerosene performs in terms of non-CO2 effects. We will see that e-kerosene has significantly lower non-CO₂ emissions and thus causes significantly less non-CO₂ effects. Although scientific research does not yet provide a final answer, it can be roughly estimated that the use of 100% sustainable e-kerosene could roughly halve the total climate impact of aviation (CO₂ and non-CO₂).
The remaining contrails and ozone formation, and consequently the overall climate impact of air traffic, could ultimately fall to almost zero if flight routes and altitudes are also optimised. However, since this would increase fuel consumption, and e-kerosene requires significantly more energy to produce than it contains, it will be necessary to balance it from a climate policy perspective: How much e-kerosene production with the needed high energy input is appropriate in relation to the total renewable energy production, as long as the energy transition is not yet complete?
Sustainable e-kerosene is therefore an important first step towards climate compatible flying and, if applied correctly, can also lead to climate-neutral flying in the long term. Until then the following applies: Flying less is better for the climate.