Sustainable aviation fuel is in for a bumpy flight

Decarbonising air travel using sustainable aviation fuel (SAF) has been rising up the news agenda on both sides of the globe. In 2022 aviation accounted for 2% of global energy-related CO2 emissions. As the developing world’s appetite for foreign holidays catches up with the West’s, this is only going to increase. So, the EU is to be commended for mandating increasing blends of sustainable aviation fuel (SAF) at European airports into the future. The RefuelEU regulation will increase the level of SAF: at least 2% of aviation fuels in 2025, increasing to 6% in 2030, 20% in 2035, 34% in 2040, 42% in 2045 and 70% in 2050. In addition, a specific proportion of the fuel mix (1.2% in 2030, 2% in 2032, 5% in 2035 and progressively reaching 35% in 2050) must comprise synthetic fuels like e-kerosene.

But are these ambitious targets credible when the current use of SAF is only 0.1%? The CEO of Lufthansa was quite negative in a recent interview. And when the going gets tough, will the governments back down and relax the targets?

Unlike most of the world, the EU has ruled out crops as a source of biofuels for SAF, even those such as intermediate crops, which do not compete with food. Instead, producers must use biogenic and fossil wastes, all of which have obvious and proven disadvantages.

Used cooking oil is the easiest waste raw materials from which to produce SAF relatively cheaply. But there is a limit to how much used cooking oil is available to be collected. Already, incentives for road transport biofuels are causing fraudulent imports of palm oil to be passed off as used cooking oil. 

Agricultural and forestry wastes are hard to process and expensive to collect. Past experience with 2nd generation biofuels for road transport has shown that these wastes have not fulfilled their original promise, apart from in a few locations. 

RefuelEU’s approval of ‘recycled carbon aviation fuels’ produced from fossil waste including gases, liquids and solids (for example waste plastics) will surely act to increase the value of fossil wastes, thereby supporting the retention of existing virgin fossil processes. Also, the greenhouse gas savings of using waste fossil material as a fuel are still not agreed upon.

In contrast, the International Civil Aviation Organization (ICAO) has approved more widely available crop based SAF, for inclusion in its Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) scheme.  The crops must be certified as coming from deforestation free land and GHG savings targets must be met. At the same time as the EU was approving the RefuelEU regulation, India announced the launch of a global biofuel alliance to boost the use of cleaner fuels. They too have committed to using only waste feedstock.  How long before countries like India decide biofuels from waste are too expensive and that it is easier to use crops?

Anyway, crops and wastes will not be a long term solution.  The world must move to using captured CO2 as the carbon source for SAF. Hence the EU’s subtarget for synthetic fuels. Governments tell their citizens that advances will bring the cost down with time.  But the difficulty of extracting carbon dioxide from a dilute source (the atmosphere at about 400 ppm) and the amount of renewable electricity needed will be costly. In a recent study e-kerosene in 2030 is predicted to be almost 2 to 3 times the average price of fossil kerosene.  In the longer term, when the capital investment is paid down, the maintenance, operation and energy costs of such a complex process are likely to remain expensive, when compared with the ease with which aviation kerosene is currently produced from oil. The head of IATA is predicting a long term premium for SAF.

In the medium term, due to the ambitious mandates for SAF and the restrictive range of allowed feedstocks, costs will start to rise faster in Europe than elsewhere in the world. The EU acknowledges that there may be adverse consequences and that measures might need to be adapted. Policy makers could row back on the mandates when people stop flying into Europe for holidays or business trips, because the fares are too high.

In the past, flying has made progress in leaps and bounds rather than small steps. Some of the advances were forged in the heat of war. Companies are now trying to integrate the old Fischer Tropsch technology developed a century ago, with direct air capture of carbon dioxide to make e-kerosene a reality. Or perhaps the future lies in a battery breakthrough and smaller electrically powered aircraft. Until the skies clear, investors in SAF production should fasten their seat belts for turbulence ahead.

Published: 9 October 23

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