Production of Sustainable Aviation Fuel in Brazil Integrating Biochemical and Thermochemical Routes. Techno-economic and Environmental Assessment Considering Alcohol to Jet and Fischer-tropsch Strategies

Abstract

While the aviation sector is trying to reach the net zero-carbon status in 2050, sustainable aviation fuel (SAF) is a possible strategy to help achieve this target. The present study compares alternative SAF production routes to meet future demands in the Brazilian and World markets. One possible SAF production chain includes the internationally approved alcohol-to-jet (ATJ) technology using the well-established Brazilian first-generation (1G) sugarcane ethanol as raw material (scenario I). This alternative was compared with technologies that utilize the excess lignocellulosic residues of the 1G sugarcane ethanol production either to produce SAF through gasification and Fischer-Tropsch (FT) synthesis combination (scenario II) or to produce more ethanol in an integrated first- and second-generation plant (1G2G) to serve as input to the ATJ process (scenario III). The assessment and comparison of the proposed SAF production alternatives were performed by adapting and using the models included in the Virtual Biorefinery (VB) platform developed by the LNBR/CNPEM to simulate the various biochemical and thermochemical integrated value chains. The major performed activities were: (i) technical, economic, and environmental assessments of sugarcane production and straw recovery; (ii) simulation of 1G and 1G2G ethanol production processes; (iii) simulation of the SAF production processes considered for the ATJ and FT alternative routes; (iv) economic and Life Cycle Assessment (LCA) of SAF production. The economic assessment results indicated that scenario I has the lower minimum selling price (MSP) for SAF (0.85 US$/L) attributed to the lower investments for the process, while scenarios II (1.10 US$/L) and III (1.07 US$/L) confirmed that the MSP of all scenarios was higher than the fossil fuel price (0.54 US$/L). Nevertheless, the technical results showed that scenario III presented a higher SAF production (135.3 million L/year) than scenarios I and II (98.5 and 114.3 million L/year, respectively). Regarding LCA, it could be mentioned that SAF emissions obtained in all scenarios (the lowest is 20.1 gCO2eq/MJ for scenario II) were lower than fossil fuel (87.5 gCO2eq/MJ). Finally, it can be indicated that the availability of sugarcane in Brazil converts the country into a potentially essential participant for the deployment of large-scale projects for SAF production, which can reduce greenhouse gas emissions compared with the conventional kerosene production chain. Furthermore, the learning curve of new technologies included in scenarios II and III, as well as the implementation of policies associated with the production of biofuels, could strongly reduce the MSP of SAF produced in integrated chains.