Reaching new heights: Flying on recycled carbon dioxide
Annually, global aviation – including domestic and international; passenger and freight – accounts for approximately 2% of human-induced CO2 emissions. This is because kerosene, a petroleum-based fuel, is mainly used to power airplanes and helicopters equipped with turbine engines.
Sustainable aviation fuels could play an important role in reducing the carbon footprint of the aviation sector in the coming years. The Dutch Ministry of Infrastructure and Water Management challenged Shell to produce a batch of 500 litres of fully synthetic kerosene out of captured CO2, water and renewable energy. The first commercial flight using this more sustainable synthetic fuel took place in January this year. The batch of 500 litres was blended with fossil-based jet fuel, for a KLM flight from Amsterdam to Madrid. No modifications were necessary to the aircraft itself to enable the flight with the sustainable fuel.
Why is this fuel considered sustainable?
Shell managed to produce the aviation fuel based on CO2, water and renewable energy. The CO2 used in the process is recycled CO2 from the Shell Pernis Refinery, and CO2 originating from the fermentation of agricultural residues. By using CO2 from industry or captured from the atmosphere, Shell limits emitting new CO2 into the atmosphere. It also avoids extracting additional fossil resources for the production of synthetic fuel.
How is the synthetic fuel produced?
An electrolyser splits water into hydrogen and oxygen. To ensure the resulting hydrogen is considered renewable, the electrolyser was powered by solar panels on the roof of the Shell Technology Centre in Amsterdam and Dutch wind turbines. Hydrogen is one ingredient for the kerosene. The second ingredient is carbon, which is obtained from the recycled CO2. Combining the renewable hydrogen and CO2 at high temperature causes a chemical reaction that creates a mixture of carbon monoxide and hydrogen called syngas. To turn the syngas into liquid fuel, a catalyst is used.
What’s next?
The next step is to scale up this technical solution and make it economically viable to further reduce the CO2 emissions of the airline industry. The chemical industry is helping the aviation sector to scale up sustainable fuels as part of the Clean Skies for Tomorrow coalition.
