Carbon Footprint of Sustainable Aviation Fuels: A Mini-Review of Trends and Prospects

The net zero emission objective requires urgent carbon reduction from the aviation sector. Sustainable aviation fuel (SAF) is deemed to reduce aviation’s greenhouse gas emissions in the short to medium term due to civil aircraft’s inherent characteristics. Though SAF is considered a low-carbon aviation fuel, its carbon footprint varies substantially depending on raw materials, techniques, regions, etc. Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) has published SAF’s default carbon footprint values; however, the findings only encompass a limited range of raw material categories, techniques, and regions, potentially compromising the evaluation accuracy. We used a thorough review of the literature to reveal the status quo of SAF and its carbon footprint. First, we constructed the process flow for SAF production from different raw materials, creating a network of integrated processes. Next, we reviewed the SAF’s carbon footprint from 194 cases across five continents. At the regional level, the average carbon footprint of SAF production was lower in South and North America. For raw materials, oil-produced SAF had the lowest carbon footprint. For techniques, the catalytic hydrothermolysis jet route has the smallest carbon footprint. Meanwhile, the results demonstrate a significant divergence between the SAF’s carbon footprint made from different raw materials using the same technique. Comparing the literature values with those from CORSIA underscores the need to include more studies in the calculation. The study finally summarizes the factors that may influence the results accuracy and highlights more environmental and socioeconomic dimensions that should be considered in future research.