Aircraft departing European airports will need to refuel with ever-increasing quantities of sustainable aviation fuels (SAFs) and hydrogen-based synthetic fuels as soon as 2025, under new blending rules agreed by the European Commission (EC).
The proposal, agreed by the EC yesterday (Tuesday), envisages planes refuelling with blends containing at least 2% of SAFs in 2025, of which 1.2% should be derived from synthetic aviation fuels — hydrocarbons such as e-kerosene made by combining carbon molecules with green hydrogen made with renewable energy.
Blend mandates will be ratcheted up every five years until they reach 70% of SAFs by 2050, of which 35% should be made from synthetic aviation fuels, sometimes called e-fuels.
But these mandates, originally floated as part of the EU’s Fit for 55 package, represent a compromise onthe European Parliament’s initial proposal to set 2050 blend targets at 85% — and the EC's counter-proposal of 63%.
Nevertheless, the EC estimates the new rules will slash EU aviation emissions by two thirds by 2050.
In particular it highlighted the strategic potential of synthetic aviation fuels to decarbonise the sector ahead of the commercial roll-out of planes powered either by pure hydrogen or batteries — a development the EC noted is someway off — and without the water use of SAFs.
Synthetic fuels such as e-kerosene have the potential to be carbon neutral if the carbon molecule used to make them is captured from the air — a process some critics have said is too energy intensive to be useful.
Budget airline Easyjet and aircraft maker Airbus have agreed to work together on direct air carbon capture (DACC) technology, but neither company has yet publicly committed funds to it.
“Synthetic aviation fuels have the potential to achieve emission savings as high as 85% or more compared to fossil aviation fuel,” the EC’s 2021 proposal reads. “When produced from renewable electricity and carbon captured directly from the air, the potential emission savings compared to fossil aviation fuel can reach 100%. As such, synthetic aviation fuels have the highest potential for decarbonisation of all fuels considered under this initiative.”
“Their production process is also particularly resource efficient, notably as regards the use of water, compared to the production of other sustainable aviation fuels pathways,” it added.
E-kerosene also has significantly lower particulate matter and aromatic chemicals than conventional kerosene, which is likely to reduce the presence of contrails in the air, themselves a contributor to global warming.
The inclusion of a synthetic aviation fuel sub-target as part of the broader SAF mandate is an effort to incentivise a scale-up of production and bring costs down, the EC said.
Currently, synthetic aviation fuels such as e-kerosene cost three- to six-times the price of conventional oil-derived aviation fuels.
The rules now need to be debated and signed off by the other two branches of EU government, the Council and European Parliament.
The broader SAF target encompasses second generation biofuels that use non-food-based feedstocks, such as used cooking oil or algae, in an effort to reduce land use — and some that are made using green hydrogen.
The most common biofuels-based SAF is HEPA-SPK (hydro-processed ester and fatty acids synthetic paraffinic kerosene), which accounts for around 95% of all biofuel flights so far.
SAFs can also be made using the Fischer-Tropsch (FT) process, in which organic biomass is heated to form a syngas of carbon monoxide and hydrogen, and refined into kerosene.
However, with pressure on producers to deliver high volumes of scarce SAFs to the aviation industry, some manufacturers are experimenting with introducing green hydrogen into the process to maximise production.
US carrier Delta Airlines recently signed an SAF supply deal with Louisiana producer DG fuels, which is adjusting the FT process to make the resulting syngas richer in carbon monoxide, and adding green hydrogen to increase production by a factor of almost four.
UPDATE: mandates updated to latest versions