Main feedstock for sustainable alternative fuels for aviation

A wide variety of raw materials for sustainable aviation (SAFs) can be used on different homologated pathways. The chapter was divided into three main categories of SAFs: sources of lipids (oils and fats), sugar and starches and lignocellulosic materials as a way of grouping the main composition of biomass. The sources of lipids are mainly composed of triglycerides and fatty acids, being suitable raw materials for the HEFA process (hydroprocessed esters and fatty acids), whose highlight is palm and macauba oils, due to the high oil quality and good yield per hectare. Sugar and starch crops are the raw materials for biochemical routes, such as alcohol to jet (ATJ) and synthesized isoparaffins (SIP) produced from fermented hydro-processed sugars, which are rich in disaccharides and polysaccharides. Analyzing the categories of SAFs for edible food crops (production of first generation biofuels) and those with low water demand, low consumption of fertilizers and pesticides, which are less competitive with food and do not require expanding the limits of agricultural products will be more appropriate and desirable. Lignocellulosic materials are inedible biomass and this makes them attractive as inputs due to their relatively low cost, great abundance and little effort for their cultivation. Normally, lignocellulosic material is mainly composed of cellulose, hemicellulose, lignin and the main challenge of its use is to carry out a conversion process in several stages to reduce the high oxygen content, which impacts on the cost of fuel and the availability of technology. The development of the SAF chain is based on the availability of the input and the price of the raw material, making it economically competitive with fossil derivatives, so there is no single option, but excellent options for different places. It is observed that several factors, direct or indirect, contribute to the consolidation of the production chain of sustainable fuels for aviation.