The production and use of sustainable aviation biofuels aims to provide a low-carbon alternative to conventional jet fuel to help reduce the environmental impacts of aviation. Scaling up sustainable aviation biofuel production and use would not be without its own environmental impacts that would need to be carefully managed. Some of the key potential environmental impacts that could result from large-scale production and use of sustainable aviation biofuels include:

Land use change – A significant amount of agricultural land and feedstock would be required to produce aviation biofuels at a large, commercial scale. This could result in indirect land use change impacts if vegetable oils, sugar crops, or other food/feed crops are used as feedstocks. Land may be converted from forests, grasslands or other ecosystems to cropland to produce biofuel feedstocks, resulting in loss of habitat, biodiversity and carbon stocks. Feedstocks from waste oils or non-edible crops grown on marginal lands could help minimize land use change impacts. Careful land use planning would be needed.

Water usage – Certain feedstock crops like corn, sugarcane, palm oil require significant quantities of water for irrigation. Large-scale production of these feedstocks could put pressure on local water resources, especially in water-stressed regions. Process water would also be needed at biorefineries. Water usage and impacts on local aquifers and watersheds would need to be carefully monitored and managed.

Fertilizer and pesticide runoff – Increased use of fertilizers and pesticides could be needed to optimize yields of biofuel feedstock crops at a commercial scale. This could increase the risks of agricultural chemicals running off farmlands and polluting waterways, contributing to eutrophication, algal blooms, loss of aquatic biodiversity and risks to human health. Best management practices would need to be implemented to minimize runoff risks.

GHG emissions – While produced and used sustainably, aviation biofuels can reduce GHG emissions vs fossil jet fuel. Factors like feedstock production, refining process energy use, transportation impacts need to be optimized to maximize lifecycle GHG savings. Some feedstock options like palm oil may cause high emissions through deforestation if not produced responsibly on already cleared lands. Continuous efforts are required to improve biofuel sustainability.

Impacts on soil health – Intensive cultivation of certain feedstock crops like corn or sugarcane could deplete soil nutrients or increase risks of soil erosion if not managed properly, especially over large areas. This could affect long-term soil productivity and health. Cropping practices need to employ techniques like cover cropping, reduced tillage, nutrient management to maintain soil carbon stocks and quality.

Biodiversity impacts – Monoculture cultivation of biofuel crops carries risks to biodiversity by reducing habitat for other species and planting non-native species. Genetically modified feedstock crops also pose risks that need assessment. Growing biofuel feedstocks on marginal lands or as part of diverse cropping systems can help reduce pressures on biodiversity. Regulatory safeguards may be required.

Food security impacts – Large-scale diversion of crops, agricultural lands or water resources for biofuel production could theoretically impact global food security by reducing availability or increasing prices of food commodities if not properly governed. Sustainable aviation fuels employ non-edible waste and residues or purpose-grown non-food crops to avoid direct competition for food. Indirect impacts would still need monitoring and mitigation.

Responsible and sustainable production of biofuel feedstocks and advanced technologies for refining can help minimize many environmental impacts of scaling up aviation biofuels. But careful governance, incentives for best practices, life cycle analysis and continuous improvements will be crucial to maximize benefits and avert unintended consequences. Vigilant monitoring of impacts with appropriate mitigation measures in place will also be important as volumes increase to commercial levels. With the right safeguards and efforts towards sustainability, aviation biofuels can provide meaningful reductions in carbon emissions to help decarbonize air travel over the long run.