Aviation fuel from carbon dioxide? Finnair is supporting its path to reality

"We want to show that Finland has the necessary raw materials, biogenic carbon dioxide, hydrogen and energy, as well as the necessary operators to produce synthetic aviation fuel," says Tuomo Karppinen, who works as a project manager at Finnair in the pilot.

Technological readiness plays a crucial role

To date, Liquid Sun has produced a so-called crude SAF intermediate at its pilot plant in Espoo, from which certified eSAF will be refined in the next process phase. Only after that can the fuel be blended with fossil aviation fuel.

Once all the key steps in terms of fuel use have been certified and the fuel has been found to be safe, Finnair's goal is to fly a commercial flight with fuel that contains synthetic eSAF produced in the pilot.

"If the flight will be implemented, it will hopefully serve as a springboard for longer-term development work and provide visibility for eSAF developers, which in turn will help attract funding for projects in the field," Tuomo says.

Finnair joined the project primarily to support the development of the technology and its introduction, and to bring the airline's perspective into the development work. The project also aims to highlight practical challenges.

"We know that the bottleneck in eSAF production at the moment is the demonstration of technical readiness. In addition, we want to transparently highlight the bottlenecks that we still need to solve in building the ecosystem. For example, one of the key questions to consider is where renewable fuel should be blended and how it can be efficiently refueled into aircraft," says Tuomo.

A significant step in the development of eSAF

Synthetic aviation fuel, or eSAF, is seen as a promising option for reducing aviation emissions. Estimates suggest that it could significantly reduce fossil carbon emissions over the full fuel lifecycle, when produced using renewable electricity and captured CO₂.

However, there are challenges along the way. So far, technology is still in its early stages, and production has not been scaled up to an industrial scale. In addition, the production of eSAF requires significant amounts of renewable electricity and raw materials such as hydrogen and carbon dioxide, the capture of which is currently expensive.

What is special about Liquid Sun's project is cost-effectiveness. They have developed a patented solution that can reduce the energy requirement in production.

"Their technology is so-called low-temperature technology, which reduces the need for energy and makes process optimization more flexible, for example, by enabling the use of cheap exchange electricity. In the future, this may enable more cost-efficient production than with current technologies," Tuomo points out.

A key role in Finnair's sustainability work

Sustainable aviation fuels play a key role in achieving Finnair's climate targets, but according to Tuomo, from the point of view of achieving the targets, a lot depends on the price development of the fuel and the maturity and scalability of the technology.

"The single biggest way to reduce emissions is the use of renewable aviation fuels. That is why we want to do everything possible to support eSAF production and technology. We alone burn about a million tonnes of fuel a year, so there certainly is demand. In 2030, the EU will introduce an eSAF blending obligation, which means that eSAF must be available and in use – but at the moment, there is not yet enough production," Tuomo points out.

In the future, the role of eSAF may grow significant if costs decrease, and the technology develops fast enough. The experts involved in the project have a unique opportunity to follow the development of technology closely.

"What inspires me the most is to see the progress of startups and technology development in practice. They have a genuine desire to make things happen – and when they commit to something, solutions are found," Tuomo concludes.

Frequently asked questions about eSAF

What is eSAF? eSAF is synthetic sustainable aviation fuel made from carbon dioxide, water and renewable electricity. It has the same chemical properties as conventional jet fuel, so it works in today's aircraft without modifications. The name stands for electro Sustainable Aviation Fuel.

What is the difference between SAF and eSAF? SAF is the umbrella term for all sustainable aviation fuel. Bio-based SAF is made from feedstocks such as used cooking oil and other waste materials, while eSAF is produced synthetically from captured carbon dioxide and hydrogen made with renewable electricity. eSAF is one type of SAF.

How is eSAF made? Renewable electricity splits hydrogen from water, and that hydrogen is combined with captured carbon dioxide to form synthetic, liquid aviation fuel.  In Finland, carbon dioxide can be captured, for example, from emissions from the forest industry and biogas plants, making it bio-based.

How much does eSAF reduce emissions?  It has been estimated (ICCT, Project SkyPower) that eSAF could reduce fossil carbon emissions by over 90% across the full fuel lifecycle—from production and distribution to use—when produced using renewable electricity and captured CO₂. The final emissions reduction depends on how the feedstocks and the electricity used in production are sourced.

Why isn't eSAF widely used yet? The technology is still in its early stages and production has not been scaled to an industrial level. Making eSAF requires large amounts of renewable electricity along with hydrogen and carbon dioxide, which are still expensive to capture. For now, only small volumes are available.

What is the EU eSAF blending mandate? The EU blending mandate requires the share of renewable aviation fuels to rise gradually. From 2030 it will also cover synthetic eSAF, and by 2050 sustainable fuels must make up 70% of aviation fuel, half of which must be eSAF.

What is Finnair doing to advance eSAF? Finnair advances eSAF by taking an active part in developing it and building the ecosystem around it. We are involved in the Finnish company Liquid Sun's eSAF pilot together with ABB, Fortum and Finavia, with the goal of showing that synthetic aviation fuel can be produced in Finland. We also help the wider market take shape through the SAF work of the Finnish Hydrogen Cluster.