Sustainable Aviation Fuels II – Technological Landscape

In the previous instalment of the Sustainable Aviation Fuels (SAF) article series, we had a look at thecurrent SAF policy landscape on the global scale, as well as in the EU and in the United Kingdom. We saw that legislative support for SAF incorporation remains very recent, and that Europe and North America are currently leading the way in this aspect. In this second article, we shed some more light on the current technological tools available for the production of SAF, as well as the main technologies being explored for future use. We show that although Asia and Africa lag behind other regions in terms of policy support, they are both aiming to place themselves at the forefront of feedstocks supply for the production of aviation fuels.

Several technologies have been developed for the production of SAF, all with varying degrees of GHG emission reductions. These technologies are often patented by producers and key players within the SAF supply sector. However, there remain similarities between them all. Most approved SAF fuels are drop-in fuels which can be blended with conventional petroleum-derived fuels at high inclusion rates, and used in conventional engines.

Contrary to sustainable fuel types commonly used for road transport where inclusion rates are limited by conventional fuels standards, Many SAF fuels can be blended to high concentrations of up to 50%ⁱ. In addition, SAF can make a significant impact in the fight to reduce GHG emissions by reducing life-cycle emissions by as much as 80%ⁱⁱ. In addition to established fuels such as HVO and ethanol-derived SAF, e-fuels and zero emissions hydrogen-based fuels are being actively researched. Although these are yet to make it to the market, the ambition is to have the world’s first zero fuel emission commercial aircraft by 2035ⁱⁱⁱ.

In this article, we start by providing an overview of the main feedstocks used for the production of sustainable aviation fuels. Then, we cover the main technologies being used to produce SAF in more detail. In addition, we look at two promising innovations which are likely to bring the sector even further in its ambition to reduce GHG emissions and to provide zero-emissions commercial flights in the near future.

Hydrotreated Esters and Fatty Acids Technology (HEFA)

HEFA technology is fully commercially deployed, and currently is the main pathway for the production of SAF globally. This process predominantly uses oils and fats as feedstocksiv. Here, fatty acids undergo hydrotreatment to produce alkanes during which nitrogen and sulphur are removed^v. Then, the next step of the process involves the hydrodeoxygenation of the feedstocks, which removes oxygen from the substrates in the presence of hydrogen. Then, the saturated hydrocarbon chains are broken down – or cracked^iv,^vi. The extent of the cracking defines the length of the chains,
which in turn defines the use that the refined product will have: typical outputs include gasoline, diesel or naphtha. To produce SAF, the diesel fraction is further refined by distillation to separate out lighter fractions suitable for jet enginesiv. HEFA was approved for use as a jet fuel in blends of up to a maximum of 50% HEFA in 2011^vii.

In the previous instalment of the Sustainable Aviation Fuels (SAF) article series, we had a look at the current SAF policy landscape on the global scale, as well as in the EU and in the United Kingdom. We saw that legislative support for SAF incorporation remains very recent, and that Europe and North
America are currently leading the way in this aspect. In this second article, we shed some more light on the current technological tools available for the production of SAF, as well as the main technologies being explored for future use. We show that although Asia and Africa lag behind other regions in terms of policy support, they are both aiming to place themselves at the forefront of feedstocks supply for the production of aviation fuels.

Several technologies have been developed for the production of SAF, all with varying degrees of GHG emission reductions. These technologies are often patented by producers and key players within the SAF supply sector. However, there remain similarities between them all. Most approved SAF fuels are drop-in fuels which can be blended with conventional petroleum-derived fuels at high inclusion rates, and used in conventional engines.

Contrary to sustainable fuel types commonly used for road transport where inclusion rates are limited by conventional fuels standards, Many SAF fuels can be blended to high concentrations of up to 50%i. In addition, SAF can make a significant impact in the fight to reduce GHG emissions by reducing life-cycle emissions by as much as 80%ii. In addition to established fuels such as HVO and ethanol-derived SAF, e-fuels and zero emissions hydrogen-based fuels are being actively researched. Although these are yet to make it to the market, the ambition is to have the world’s first zero fuel emission commercial aircraft by 2035ⁱⁱⁱ.

In this article, we start by providing an overview of the main feedstocks used for the production of sustainable aviation fuels. Then, we cover the main technologies being used to produce SAF in more detail. In addition, we look at two promising innovations which are likely to bring the sector even further in its ambition to reduce GHG emissions and to provide zero-emissions commercial flights in the near future.

Hydrotreated Esters and Fatty Acids Technology (HEFA)

HEFA technology is fully commercially deployed, and currently is the main pathway for the production of SAF globally. This process predominantly uses oils and fats as feedstocks^iv. Here, fatty acids undergo hydrotreatment to produce alkanes during which nitrogen and sulphur are removed^v. Then, the next step of the process involves the hydrodeoxygenation of the feedstocks, which removes oxygen from the substrates in the presence of hydrogen. Then, the saturated hydrocarbon chains are broken down – or crackediv,vi. The extent of the cracking defines the length of the chains,
which in turn defines the use that the refined product will have: typical outputs include gasoline, diesel or naphtha. To produce SAF, the diesel fraction is further refined by distillation to separate out lighter fractions suitable for jet engines^iv.

HEFA was approved for use as a jet fuel in blends of up to a maximum of 50% HEFA in 2011^vii.

… you may read the full article under https://www.nnfcc.co.uk/files/mydocs/Sustainable%20Aviation%20Fuels%20II%20-%20Technological%20Landscape.pdf

Source

NNFCC, press release, 2022-03-11.

Supplier

NNFCC

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