Fuelling the future: Closing the loop in sustainable aviation
Mika Järvinen, Associate Professor at Aalto University, explains how Circular Fuels is working to close the loop in sustainable aviation.
As the climate crisis reaches higher altitudes and the pressure to decarbonise soars, the aviation industry faces a choice: innovate or risk a turbulent future.
Responsible for 14.4% of the EU’s transport-related emissions, air travel remains one of the most carbon-intensive sectors and one of the hardest to decarbonise.
While electric vehicles are becoming increasingly mainstream for road transport, the dream of battery-powered long-haul flights remains distant.
The aviation sector remains dependant almost entirely on fossil fuels, contributing greatly to our current climate crisis. We must cut these carbon emissions in order to reduce our impact on the planet.
In Europe, there has been some movement towards a fossil free future in recent years. In 2021, the EU presented the Fit for 55 plan aiming to cut greenhouse gas emissions by a 55% reduction by 2030 in comparison to 1990 levels.
To help reach this target, they also introduced initiatives aiming to boost the use of cleaner aviation fuels and reduce the environmental impact.
After discussions throughout 2022 and 2023, EU leaders and the European Parliament finally reached an agreement, and the ReFuelEU Aviation regulation was officially adopted in October 2023.
The solution is clear. To advance aviation and reach these ambitious targets set by the EU, we must take a more radical approach rooted in the circular economy principles.
Closing the loop in sustainable aviation
Launched in 2023, with the backing of the EU’s Green New Deal and CORDIS initiatives, the Circular Fuels project is redefining how sustainable aviation fuels (SAF) can be developed, scaled, and integrated into our global energy system.
Not only does this project present technological upgrades, it also offers a systems-level rethinking, bringing circularity to the skies by integrating renewable energy, waste-based inputs, and zero-emission processes into a closed-loop model.
At its core, Circular Fuels is built on the foundation of circularity. Rather than relying on extractive, linear production chains that take, make, and waste, this project takes a regenerative approach.
Waste materials, including agricultural residues and forestry byproducts, are transformed into valuable bio-oils, which are then refined into high-quality, drop-in aviation fuels.
But the innovation doesn’t stop at feedstock. The process is powered entirely by solar energy, both through photovoltaic (PV) electricity and concentrated solar thermal systems.
Parabolic mirrors harness solar heat to generate temperatures over 3000°C, which are then funnelled into pyrolysis reactors that convert biomass into bio-oil. This heat production involves no combustion, meaning no carbon emissions. It’s a major leap forward in sustainable energy practices.
Meanwhile, solar PV powers PEM (Proton Exchange Membrane) electrolysers are used to produce green hydrogen from water. This hydrogen is essential for the hydrotreatment of bio-oil, removing oxygen and refining the product to meet the strict quality requirements of aviation fuels.
Every step in the process is deliberately designed with circularity in mind to eliminate waste, close energy loops, and minimise environmental impact.
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Read the full article on Circularonline.co.uk
