氣候變遷對跨太平洋航線之影響及永續航空燃料應用之成本效益分析

The Impact of Climate Change on Trans-Pacific Flights with Cost-Benefit Analysis of the Use of Sustainable Aviation Fuels

航空業與氣候變遷有相互影響之關係，航空器排放溫室氣體促進氣候變遷；而氣候變遷則直接影響航班營運。本研究評估氣候變遷對民航機在巡航階段的影響，並探討其影響所衍生之環境與財務成本；再分析以永續航空燃料（Sustainable Aviation Fuel, SAF）作為長期調適措施之成本效益。實證分析結果顯示，氣候變遷會增長跨太平洋航線之旅程時間，以臺北洛杉磯航線為例，國籍航空公司每年總計將額外支出新臺幣2,456萬燃油成本，整體北美航線則增加新臺幣9,512萬；而環境社會成本主要來自二氧化碳與氮氧化物。另外，唯有在傳統油料價格上升或SAF價格下降時，使用SAF才符合成本效益；敏感度分析顯示，在高二氧化碳價格情況下，若SAF價格下降至現有之70%時，使用SAF之環境效益將高於其增加之購油成本。

Increasing economic development has caused a rise in greenhouse gas (GHG) emissions over the past century. These emissions lead to global warming and hence climate change. The commercial aviation sector is a major contributor to this, accounting for about 2% of global man-made carbon dioxide (CO_2) emissions, and expected to reach around 4% by 2050 (IPCC, 2014). Conversely, climate change affects aviation since changes to temperature, and wind speed, lead to changes to flight routes, which thus causes extra journey time, fuel consumption and operating costs; and so to yet more GHG emissions. This paper aims to explore the impacts of climate change on the cruise stage of commercial flights on trans-Pacific routes and evaluate both the environmental and financial costs of extra fuel consumption, and analyzing the cost-benefit of using sustainable aviation fuel (SAF) as a potential long-term adaptation measure. The empirical results for TPE-LAX flights show that climate change is expected to lengthen the journey time of these flights, causing an extra fuel cost of NT$ 24.5 million for Taiwanese airlines. This translates to an extra NT$ 95.1 million for northern trans-Pacific flights for these airlines. Of all the exhaust pollutants, CO_2 and NO_X are responsible for the majority of the environmental social costs during the cruise stage. Incentives for the use of SAF in commercial flights could potentially derive from an increase in traditional fuel price or a reduction in biofuel price. The sensitivity analysis shows that, in a high CO_2-cost scenario, if the additional cost of replacing traditional fuel by SAF for the extra travel time caused by climate change is to be less than the environmental benefit of using SAF, the price of biofuel must be reduced to 70% of its current level.