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 macro-regions of Brazil, including sugarcane and maize ethanol to jet (ATJ) 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 (BLUES) Integrated Assessment Model (IAM) 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 and the type of feedstock used. 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.

Double-cropped Corn Ethanol in Brazil: An existing food-energy system that contributes to multiple Sustainable Development Goals

“…By introducing this system in the socio-economic models, we correctly represent farmers' trade-offs and opportunities when deciding how to better allocate land among single-cropping and doublecropping systems. This statement is reinforced by Fiorini et al (2023) 36 , which finds robust negative ILUC for Sustainable Aviation Fuels (SAF) produced from second-crop corn in Brazil, bringing different scenarios. Examples of other second crops, also called double crops, are increasingly being noted in scientific literature [37][38][39][40][41][42][43] .…”

Integration of Plant and Microbial Oil Processing at Oilcane Biorefineries for More Sustainable Biofuel Production

“…62,63 However, the use of feedstocks such as corn (through the alcohol-to-jet pathway) and soybean (through hydroprocessed esters and fatty acids) for SAF production is linked with high land use expansion that limits our ability to scale. 64 The configurations for plant and microbial oil processing developed in this study may provide an avenue for even greener and more scalable biomass-based SAF. Further techno-economic and life cycle assessment studies are needed to quantify the potential benefits of plant/microbial oil pathways to oil-based biofuels and oleochemicals other than biodiesel.…”

Biofuels in Aviation: Exploring the Impact of Sustainable Aviation Fuels in Aircraft Engines

“…Certain feedstocks, such as those cultivated on marginal or degraded lands, present lower ILUC risks, leading to significant reductions in GHG emissions [41]. Advanced biofuel pathways, like hydroprocessed esters and fatty acids (HEFAs) and Fischer-Tropsch (FT), have shown promise in reducing GHG emissions when appropriate safeguards are in place to minimize deforestation and other high-emission activities [86]. Another pathway for GHG reduction is the utilization of oilseed cover crops, which can serve as feedstocks for biofuels without requiring additional agricultural land.…”

“…Effective land conservation strategies, combined with sustainable agricultural practices, are essential for ensuring that SAF contributes to environmental sustainability without causing undue harm to biodiversity and land use. The integration of SAF production with existing agricultural systems and the use of cover crops can help maintain biodiversity while providing a reliable source of biofuel feedstock [86,87].…”