Air traffic and CO2 (Michael Trestl) | 4pi Climate Symposium II

Thank you, Gerd, for the invitation. Ladies and gentlemen, I have come here to talk about the decarbonization of aviation and sustainable aviation fuels (SAF). I am not a natural scientist but an economist, so I will present the reality of aviation. Aviation accounts for 2.8% of global CO2 emissions, and only 4% of that comes from short-haul flights. So we should not focus on banning short-haul flights, but on the 96% that cannot be shifted to rail, like transatlantic travel. Aviation generates economic growth, jobs, and intercultural exchange. In Germany, it supports around one million jobs and 60 billion euros in value added. We follow science-based targets: 50% reduction in CO2 by 2030 and net-zero by 2050. The central part of this is actual reduction through three pillars: avoid (shift to rail where possible), reduce (new aircraft technologies, operational efficiency, and a single European sky could save 10% of emissions), and compensate. SAF is key. Biogenic SAF from used cooking oils, like those from schnitzel production, is currently 4 to 6 times more expensive than fossil kerosene but saves up to 80% CO2. The future lies in power-to-liquid and sun-to-liquid, which are 100% CO2 neutral but require enormous amounts of renewable energy. For example, to cover Germany's kerosene demand of 10 million tons per year with power-to-liquid would need 250 terawatt-hours, about 40% of Germany's total electricity consumption. Large-scale production will likely be in South America or Africa. In Austria, we produced 1,500 tons of biogenic SAF in 2023, saving 3,750 tons of CO2, equivalent to 330 flights from Vienna to London. Economic viability requires competitive costs. A Zurich-Vienna flight with 100% SAF would cost about 62 euros extra each way. Only about 10% of consumers are willing to pay such a premium, but for business travel, the total cost can still be competitive with rail when considering time and hotel costs. The EU is moving toward mandatory SAF blending, starting at 2% in 2025 and reaching 85% by 2050. Switzerland is developing similar rules. However, there is a risk of carbon leakage if Europe acts alone; hubs like Istanbul or Dubai could attract traffic, undermining global climate goals. Other technologies like battery-electric aircraft are limited to 300–400 kilometers and small capacity, possibly by 2025. Hydrogen could help for medium ranges but requires huge infrastructure changes. SAF, especially power-to-liquid, remains the most important measure for global aviation. In conclusion, air travel will continue to contribute to global prosperity, but we must pursue decarbonization through sustainable fuels. Thank you.