Decarbonisation Technology - February 2023


ASTM Annex Year of

Feedstock options

Current blending limits


Co-processing of mono-, di-, and triglycerides, free fatty acids, and fatty acid esters Co-processing of hydrocarbons derived from synthesis gas via Fischer-Tropsch process using iron or cobalt catalyst

A1.2.2.1 2018 Mono-, di-, and triglycerides, free

fatty acids, and fatty acid esters




A1 .2.2.2 2020

Fischer-Tropsch hydrocarbons

Table 2

anticipated to come into effect. All of which is great news for efforts to decarbonise aviation. Routes to SAF certification Aircraft flying around the world will be fuelled at different airports in different countries, making international fuel specifications for SAF a necessity. According to the International Civil Aviation Organisation (ICAO), there are currently 59 airports worldwide distributing SAF. Europe and the US are the main hubs, with ongoing deliveries also occurring in Malaysia, Japan, New Zealand, and at China’s Tianjin Airport. We already see current specifications ensuring that today’s engines and aircraft do not have to be redesigned to run on SAF, thus making the transition even more achievable. At present, the focus is on SAF as a drop-in replacement to conventional jet fuel. Moreover, with current ASTM standards excluding the use of pure SAF in aircraft, a 50% blend is most common, with a maximum 10% blend available in some cases. There are currently seven approved technology pathways to producing drop-in SAF (see Table 1 ). Co-processing, as seen in Table 2 , is another option for decarbonising aviation and meeting the criteria for the Standard Specification for Aviation Turbine Fuels (D1655). Co-processing, which involves the simultaneous processing

of fossil and renewable feedstocks, means you can use existing refining, transport, and storage facilities. This, in turn, makes it possible to convert renewable feedstocks into drop-in, ultra-low sulphur renewable jet or e-Jet fuel at economically competitive prices. Topsoe routes to SAF At Topsoe, we have identified the main routes we consider to be the most commercially advanced. Firstly, we have HydroFlex, which offers full feedstock flexibility whatever raw material you choose to work with. Since no two refineries or feedstock supply chains are the same, we have tailored our approach to make HydroFlex as dynamic as possible. This means more businesses will have the opportunity to use this type of SAF. This technology utilises Topsoe’s hydroprocessing expertise to enable the processing of virgin oils, waste oils and fats, solid biomass, and plastic waste/ tyres into HEFA-based SAF with minimal Carbon Intensity (CI) compared to traditional kerosene aviation fuel. Regardless of the type or quality of renewable feedstock used, the outcome is consistently high-grade, clean fuel. HydroFlex also has a high number of operating references, offers versatile process design and

Product upgrade Topsoe’s hydroprocessing and hydrogen technologies

Fischer - Tropsch conversion Sasol’s LTFT technology

Syngas generation Topsoe’s Syncor reforming technology

Waxy syncrude


Figure 1 How G2L works


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