Sustainable aviation fuels must control induced land use change: an integrated assessment modelling exercise for Brazil

Abstract

Bio-sustainable aviation fuels (bio-SAFs) are an important pillar of the aviation sector decarbonisation strategy in the mid-term. Here we assess the induced Land-Use Change (LUC) implications of producing bio-SAFs in Brazil under different assumptions of forest conservation governance. We evaluate four bio-SAF routes via two main pathways: the Alcohol-to-Jet (ATJ) and the Hydroprocessed Esters and Fatty Acids (HEFA) syntheses. We chose the most promising agriculture-based feedstocks to produce bio-SAFs in all five macro-regions of Brazil, including sugarcane and maize ethanol to jet and palm and macaw HEFA routes. To this end, we calculated future projections of air transport demand in Brazil and used the Brazilian Land Use and Energy Systems integrated assessment model to estimate LUC greenhouse gas (GHG) emissions within five different levels of bio-SAF blends (10% to 50% of total aviation fuel demand) for each bio-SAFs evaluated. Estimated cumulated emissions vary widely, ranging from a carbon sequestration of −286.8 gCO2e.MJ−1 for a 10% blend of maize ATJ under a controlled deforestation scenario to a release of 15.0 gCO2e.MJ−1 for a 40% blend of high productivity macaw oil HEFA considering historical deforestation rates in the country. Results are highly sensitive to deforestation rate parameters, volume of bio-SAFs produced, the type of feedstock used, and methodological assumptions. Negative LUC GHG emissions were found under controlled deforestation assumptions and in low blends of bio-SAFs for maize and sugarcane ATJ routes. Under historical deforestation rates, the LUC GHG emissions are higher. Bio-SAF can be beneficial to reduce GHG emissions if effective land conservation policies are implemented. Therefore, large-scale bio-SAF production from sugar crops in Brazil may play an important role in the decarbonisation of the aviation sector if coupled with successful strategies to control deforestation. Additionally, when imposing bio-SAF demand, other biofuels demand reduces under the model optimal solution due to land restrictions.