Close-up of an airplane turbine.

PtX technology as the key to climate-friendly aviation

International aviation is responsible for a large proportion of global greenhouse gas emissions. Synthetic fuels made from green hydrogen are currently the most promising option for aviation that is greenhouse gas-neutral. PtX Lab Lausitz is working to facilitate market ramp-up for these sustainable fuels.

In 2018, aviation was responsible for three percent of global CO2 emissions, a figure roughly equal to the annual emissions of developed countries like Germany or Japan. Other factors such as contrails also have an equally substantial effect on the climate. With the Paris Agreement, the global community has set itself the goal of limiting the increase in the Earth's average temperature to below 2 degrees Celsius and, if possible, to 1.5 degrees Celsius above pre-industrial levels. To achieve this, the EU wants to reduce its total greenhouse gas emissions by 55 percent by 2030 compared to 1990 levels. The German Federal Climate Change Act (“Bundes-Klimaschutzgesetz”) requires the transport sector to cut its greenhouse gas emissions by 42 percent by 2030 and become greenhouse gas-neutral by 2045.

Target: net zero emissions

Some of the reductions in CO2 necessary can be achieved by measures such as improving efficiency. Reducing the overall volume of air traffic is needed anyway to achieve savings at the sheer scale that is required.

In 2016, the International Civil Aviation Organisation (ICAO) at the UN adopted CORSIA, the ‘Carbon Offsetting and Reduction Scheme for International Aviation’: this requires aeroplane operators to report their CO2 emissions and partially offset these by purchasing carbon credits. Flights inside the European Economic Area are subject to the European Union emission trading scheme (EU ETS), which exists in parallel to CORSIA.

Sustainable alternatives to fossil fuels

Even together, these measures do not make aviation greenhouse gas-neutral, however. To achieve this, fossil kerosene must be replaced with sustainable, greenhouse gas-neutral alternatives. The use of synthetic fuels, produced from green hydrogen using a Power-to-Liquid (PtL) method, is the most promising option in this context. Mixing PtL kerosene with conventional kerosene before refuelling aircraft offers a way to significantly lower CO2 emissions over the short term.

To accelerate the market ramp-up of PtL products and achieve climate targets, the German federal and state governments have agreed a roadmap with representatives of the aviation sector. This roadmap envisages the use of 200,000 t of PtL kerosene in the German aviation sector – corresponding to an admixture quota of two percent – by 2030. In July 2021, the EU published its ‘Fit for 55’ package of measures, which recommended introducing an admixture quota of at least five percent of sustainable aviation fuels by 2030 for all flights starting within the EU. Of these five percent, at least 0.7 percent should be Power-to-Liquid-based fuels.

Some airlines have now already tested the use of biokerosene, i.e. jet fuel made from biogenic raw materials. However, the available potential of biogenic raw materials to produce bio-kerosene is not sufficient to cover aviation fuel demand, especially as a result of land and utilisation competition. Nor is the production of this biomass always in line with the principles of sustainability.

Hydrogen has to be green

A truly sustainable reduction in CO2 emissions is possible only if the hydrogen required for manufacturing the PtL kerosene has been produced using renewable energy sources (green hydrogen). The energy required for this step and the corresponding generation capacities must also therefore be available. Setting up these production capacities also requires compliance with strict sustainability criteria.

PtX Lab: a driver for change

PtX Lab Lausitz is promoting the manufacture of synthetic kerosene on the basis of renewable energy and developing strategies for the market ramp-up of sustainable PtL fuels in aviation. The construction of a PtL demonstration facility is also planned in Lusatia. Another point of focus will be the responsible handling of the resources and materials required.