Becken Susanne, Mackey Brendan, Lee David S
Griffith Institute for Tourism, Griffith University, Qld 4222, Australia; School of Tourism and Hospitality Management, University of Surrey, Guildford, United Kingdom.
Climate Action Beacon, Griffith University, Qld 4222, Australia.
Sci Total Environ. 2023 Aug 15;886:163883. doi: 10.1016/j.scitotenv.2023.163883. Epub 2023 May 8.
Aviation is highly dependent on liquid fossil fuel, and the production of 'sustainable aviation fuels' (SAF) is being proposed as a solution to removing the fossil carbon component, especially for long-haul flights. An analysis of 12 aviation roadmaps for net zero 2050 reveals heavy reliance on biogenic SAF in the medium-term and synthetic e-kerosene in the longer term. Realising these roadmaps could require 9 % of global renewable electricity and 30 % of sustainably available biomass in 2050, with significant energy 'losses'. The continued use of hydrocarbon fuel in the roadmaps generates 1.35 GtCO in 2050, of which 30 % are still from fossil fuel. The net carbon savings from the 70 % depend on the direct and indirect life cycle emissions of producing SAF. Additional effects that are omitted in most roadmaps relate to decadal time lags in re-sequestering biocarbon in the case of forest biomass and the impact of non-CO emissions. Both require greater scrutiny in fully understanding the climate impact of SAF substitution. The scaling up of SAF to not only maintain but grow global aviation is problematic as it competes for land needed for nature-based carbon removal, clean energy that could more effectively decarbonise other sectors, and captured CO to be stored permanently. As such, SAF production undermines global goals of limiting warming to 1.5 °C; a conflict that is neither recognised in the roadmaps nor in the public debate.
航空业高度依赖液态化石燃料，因此有人提议生产“可持续航空燃料”（SAF），作为去除化石碳成分的解决方案，特别是对于长途航班而言。一项对2050年净零排放的12份航空路线图的分析显示，中期严重依赖生物基SAF，长期则依赖合成电子煤油。要实现这些路线图，2050年可能需要全球9%的可再生电力和30%可持续利用的生物质，同时会有大量能源“损失”。路线图中继续使用碳氢燃料在2050年将产生13.5亿吨二氧化碳，其中30%仍来自化石燃料。70%的净碳减排量取决于生产SAF的直接和间接生命周期排放。大多数路线图中忽略的其他影响包括，在森林生物质的情况下，生物碳重新封存的十年时间滞后，以及非二氧化碳排放的影响。在全面理解SAF替代的气候影响方面，这两者都需要更严格的审查。扩大SAF的生产规模以维持甚至扩大全球航空业存在问题，因为它会与基于自然的碳去除所需的土地、能更有效地使其他部门脱碳的清洁能源以及要永久储存的捕获二氧化碳展开竞争。因此，SAF生产破坏了将升温限制在1.5摄氏度的全球目标；这一冲突在路线图和公众辩论中都未得到承认。
