TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
Sci Total Environ. 2023 Aug 10;885:163881. doi: 10.1016/j.scitotenv.2023.163881. Epub 2023 May 3.
A comprehensive framework is proposed for Life Cycle Assessment (LCA) in the field of commercial aviation (passengers and cargo), capable to ensure transparency and comparability when evaluating the overall environmental performances of four emerging aviation systems, i.e., biofuels, electrofuels, electric, and hydrogen. The projected global revenue passenger kilometer (RPK) and is suggested as the functional unit for two timeframes representing near-term (2035) and long-term (2045), and for two segments, namely domestic and international. To solve the difficulty of comparing liquid fuels and electric aviation, the framework proposes a methodology to translate projected RPK into energy requirements for each of the studied sustainable aviation systems. Generic system boundaries are defined with their key activities for all four systems, with the biofuel system being sub-divided into two categories to distinguish whether it stems from residual or land-dependent biomass. The activities are grouped in seven categories: (i) conventional (fossil-based) kerosene activity, (ii) conversion processes from feedstock supply (to fuel or energy production for aircraft operation), (iii) counterfactual uses of constrained resources and displacement effects associated to co-products management, (iv) aircraft manufacture, (v) aircraft operation, (vi) additional infrastructure needed, and (vii) end-of-life management (aircraft and batteries). Considering applying regulations, the framework also includes a methodology to handle: (i) hybridization (the use of more than one source of energy/propulsion system to power an aircraft), (ii) the mass penalty affecting the number of carried passengers in some of the systems, and (iii) impacts stemming from non-CO tailpipe emissions - aspects that are currently neglected in most LCA studies. The proposed framework builds upon the most recent knowledge in the field; however, some choices are dependent on upcoming scientific advances concerning e.g., tailpipe emissions at high altitude and their environmental impacts, new aircraft configuration, etc., and are subject to significant uncertainties. Overall, this framework provides a guideline for LCA practitioners addressing new energy sources for future aviation.
提出了一个用于商业航空（乘客和货物）领域的生命周期评估（LCA）的综合框架，能够在评估四种新兴航空系统（生物燃料、电燃料、电动和氢能）的整体环境性能时确保透明度和可比性。建议以预计的全球收入乘客公里数（RPK）作为功能单位，用于代表近期（2035 年）和远期（2045 年）的两个时间框架，以及国内和国际两个部分。为了解决比较液体燃料和电动航空的困难，该框架提出了一种将预计的 RPK 转换为所研究的可持续航空系统每一种能源需求的方法。为所有四种系统定义了通用的系统边界及其关键活动，其中生物燃料系统分为两类，以区分其是否源自残余或依赖土地的生物质。活动分为七类：（i）常规（基于化石的）煤油活动，（ii）从原料供应到燃料或飞机运行能源生产的转化过程，（iii）受约束资源的替代用途和副产物管理相关的位移效应，（iv）飞机制造，（v）飞机运营，（vi）所需的额外基础设施，以及（vii）飞机和电池的报废管理。考虑到适用法规，该框架还包括一种处理以下方面的方法：（i）混合动力（使用多种能源/推进系统为一架飞机提供动力），（ii）某些系统中对携带乘客数量产生影响的质量惩罚，以及（iii）源自非 CO 尾管排放的影响——这是目前大多数 LCA 研究中忽略的方面。所提出的框架建立在该领域的最新知识基础上；然而，一些选择取决于即将到来的科学进步，例如高空尾管排放及其环境影响、新的飞机配置等，并且存在很大的不确定性。总体而言，该框架为解决未来航空新能源的生命周期评估从业者提供了指导。
