Towards Zero Carbon Aviation (TOZCA)

2015年，全球客运和货运商用飞机的二氧化碳排放量为8.66亿吨，占能源使用相关二氧化碳排放量的2.7%，是整个英国经济排放量的两倍多。如果航空客运和货运收入吨公里（RTK）继续以每年约4.5%的速度增长，并且每RTK的机队燃料使用量继续以每年2%的速度下降，那么预计RTK的强劲增长将导致二氧化碳排放量每年增加2.5%，到2050年翻一番。二氧化碳排放量的这种增长趋势与《巴黎协定》规定的减少整个经济范围二氧化碳排放量的全球努力形成强烈对比。虽然简单的算术意味着净零碳航空系统只能通过颠覆性的飞机技术和燃料来实现，但其最具成本效益的组成仍不清楚。这些知识至关重要，因为飞机制造商、燃料供应商、航空公司和机场需要大量投资才能完成过渡。此外，向净零碳航空系统过渡需要了解基础技术路线图，辅之以扶持性政策措施和确定早期采用者。与此同时，航空系统从开发早期概念到机队采用最终产品的多重时间滞后，加上商用飞机的使用寿命长达25年，需要迅速采取行动，以便在本世纪中叶之前产生重大影响。这反过来又要求考虑所有二氧化碳减排备选方案，包括旅行需求管理，这就需要更好地了解旅行行为。TOZCA项目将开发一套全面的工具套件，以模拟到2050年和2070年实现净零碳航空系统的最具成本效益的过渡。TOZCA项目将利用这套工具，查明通过改变技术、燃料、操作、使用竞争模式和改变消费者行为而大幅度减少二氧化碳排放量所产生的技术、经济和环境协同作用和权衡。

In 2015, global passenger and freight commercial aircraft accounted for 866 million tonnes or 2.7% of energy use-related CO2 emissions, which is more than twice the amount released by the entire UK economy. If air passenger and freight revenue tonne-km (RTK) continue to grow at around 4.5% per year and aircraft fleet fuel use per RTK continues to decline by 2% per year, the projected stronger growth in RTK would lead to an increase in CO2 emissions by 2.5% per year, a doubling by 2050. This growth trend in CO2 emissions is in strong contrast to global efforts to reduce economy-wide CO2 emissions as mandated by the Paris Agreement. Whereas simple arithmetic implies that a net zero-carbon aviation system can only be achieved through disruptive aircraft technologies and fuels, its most cost-effective composition remains unclear. Such knowledge is critical as vast investments will be required by aircraft manufacturers, fuel suppliers, airlines and airports to accomplish the transition. In addition, transitioning towards a net zero-carbon aviation system requires understanding the underlying technology roadmap, complemented by enabling policy measures and identification of early adopters. At the same time, the multiple time lags in the aviation system, from developing an early concept to fleet adoption of the final product, in addition to the long lifetime of commercial aircraft in the order of 25 years, demand swift action to generate a significant impact by mid-century. This, in turn, requires that all CO2 mitigation options are considered, including travel demand management, which necessitates an improved understanding of travel behaviour. The TOZCA project will develop a comprehensive tool suite to simulate the most cost-effective transition toward a net zero-carbon aviation system by 2050 and a later 2070 date. Using this tool suite, the TOZCA project will identify the technological, economic and environmental synergies and trade-offs that result from drastic CO2 emissions reductions through changes in technology, fuels, operations, use of competing modes and change in consumer behaviour.