Environmental analysis of innovative sustainable composites with potential use in aviation sector-A life cycle assessment review

The forecast of growing air transport in the upcoming decades faces the challenge of an increasing environmental impact. Aviation industry is working on promising technologies to mitigate this environmental impact. Lightweight design is a strong lever to lower the fuel consumption and, consequently, with it the emissions of aviation. High performance composites are a key technology to help achieve these aims thanks to their favourable combination of mechanical properties and low weight in primary structures. However, mainly synthetic materials such as petrol based carbon fibres and epoxy resins are used nowadays to produce composite in aviation. Renewable materials like bio-based fibres and resin systems offer potential environmental advantages. However, they have not found their way into aviation, yet. The reasons are reduced mechanical properties and, especially for the use of natural fibres, their flammability. Improvements of these shortcomings are under investigation. Therefore the application of bio-based and recycled materials in certain areas of the aircraft could be possible in the future. Good examples for applications are furnishings and secondary structures. The motivation for this paper is to give an overview of potential environmental properties by using such eco-materials in aviation. Life cycle assessment (LCA) is a tool to calculate environmental impacts during all life stages of a product. The main focus is laid on the bio-fibres flax and ramie, recycled carbon fibres and bio-based thermoset resin systems. Furthermore an overview of environmental aspects of existing composite materials used in aviation is given. Generally, a lack of LCA results for the substitution of synthetic materials by bio-based/recycled composite materials in aviation applications has been identified. Therefore, available information from other transport areas, such as automotive, has been summarized. More detailed LCA data for eco-composite materials and technologies to improve their properties is important to understand potential environmental effects in aviation.