Decarbonisation Technology - May 2024 Issue

SAF, bio-SAF, and eSAF: What is the difference?

Renewable energy

CO point sources

Direct air capture

Agri residues, wood waste, municipal solid waste, energy crops

Vegetable oils, algae

Used cooking oil, animal fats

rNG Anaerobic digestion Gas gasication (SGP)

Water electrolyser

Reverse water gas shift

Torrefaction

Fermentation

Syngas to alcohol

Solids gasication

Hydrotreating: Shell R enewable R efining P rocess

Shell Fi b er C onversion T echnology

Hyrdo- pyrolysis

Alcohol to jet

Fischer – Tropsch

Hydroprocessing

Synthetic aviation fuel

Bio-SAF

Figure 1 SAF feedstocks and processing pathways

place until at least 2032. These provisions can contribute to the viability of specific SAF-related projects in the US. SAF feedstocks and technology pathways Regulatory frameworks, such as the EU’s RED II and ReFuelEU Aviation, define SAF incorporation targets and specify feedstock types. In the EU, UCO-based diesel comprises a substantial 19% of total biodiesel consumption, and this is projected to double by 2030. Despite the relative ease of processing through hydrotreating, this feedstock faces supply Broadly, there are three types of SAF – bio-SAF, recycled carbon fuel (RCF), and eSAF – and numerous technology pathways to create them (see Figure 1 ). Bio-SAF feedstocks can be classified into three groups: • Vegetable oils (such as canola or corn oil) and algae. • Waste oils and animal fats, such as UCO. UCO is a byproduct of the food processing and hospitality industries and one of the most mature feedstock options for biofuel production. • A range of wastes and residues derived from agricultural and forestry activities (such as straw and bark, and other fruit and vegetable residues

limitations, particularly as the industry seeks to scale up production to make a more substantial impact on reducing carbon emissions. Although more challenging to process, organic feedstocks such as agricultural residues and biowaste can be processed using a variety of methods. An example is Shell Fiber Conversion Technology, which converts lignocellulosic biomass such as wet distillers grains from corn ethanol plants into enhanced-protein animal feeds, distillers corn oil, and cellulosic ethanol. Ethanol of any origin, including ethanol manufactured through biochemical and waste); materials from natural conservation practices (including urban maintenance of green areas, branches and leaves); and urban or industrial non-recyclable waste. In the case of non-recyclable waste containing both biogenic and non-recyclable plastic components, resulting SAF under EU regulations would be seen as partially bio-SAF and partially RCF. eSAF is produced by combining renewable power, water, and CO₂. In the EU, when renewable power is used to make hydrogen, the resulting eSAF qualifies as a renewable fuel of non-biological origin (RFNBO) under RED II.