Development of a TREMOD cluster model for aviation

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Besides the ordinary greenhouse gases, aviation also produces so-called non-CO₂ effects, which have an impact on the climate. Since these effects, which include nitrogen oxide emissions at high altitude and contrails, account for more than two thirds of the climate impact of aviation according to the current state of knowledge. Thus, the determination of the effects is increasingly in focus. However, in contrast to determining the climate impact of ordinary greenhouse gases, the calculation is much more complex and is therefore subject of many studies worldwide.

In TREMOD-AV, the emission calculation tool used by the Federal Environment Agency for aviation, a simple additional factor (EWF) determines currently the non-CO₂ effects. This factor applies to all flight components from a cruising altitude of over nine kilometers. Therefor only information regarding the flight length and the corresponding number of flights apply to the calculation of the non-CO₂ effects.

However, this approach cannot adequately reflect the current scientific knowledge about the climate impact of non-CO₂ species, because factors such as the geographical region over which a flight takes place or the emission behaviour of the turbines also have a significant influence on the non-CO₂ effects. The currently used methodology could also mean that environmental policy incentives for more climate-friendly flying are not set correctly. This is also proven by the results and findings of the projects “Integration of Non-CO₂ Effects of Aviation in the EU ETS and under CORSIA” and “Untersuchung der praktischen Umsetzung der Einbindung von Nicht-CO₂-Treibhausgas-Effekten des Luftverkehrs in das EU-ETS einschließlich Clusteranalyse”, both on behalf of the Federal Environment Agency. Following these projects, a method for a more realistic representation of these effects must include additional information on the flight routes and flight altitude. The current calculation method in TREMOD-AV is not suitable for this.

In the current project “Development of a TREMOD cluster model for aviation” the method for estimating the non-CO₂ effects is implemented in the models TREMOD-AV and TREMOD according to the results of the project “Untersuchung der praktischen Umsetzung der Einbindung von Nicht-CO₂-Treibhausgas-Effekten des Luftverkehrs in das EU-ETS einschließlich Clusteranalyse“. The implementation is covering the statistically recorded years from 1990 and additionally the years up to 2050 in a scenario.