This research investigates alternative biomass feedstocks for environmentally improved composites in the aviation industry. It addresses challenges and opportunities associated with biomass use and proposes a sustainable biomass feedstock for bio-methanol production as a carbon fibre precursor for composites. The aim is to evaluate the environmental implications and practical considerations of utilizing this feedstock for sustainable bioeconomy models. The study emphasizes the importance of lightweight carbon fibre composites in meeting emission reduction targets in aviation. It identifies biomass feedstocks for methanol production as a viable strategy for manufacturing sustainable composites. However, the sustainability of this approach is highly dependent on the strategies for biomass sourcing. A need to move from bioeconomy models based on the extraction of resources towards restorative systems based on Ecosystem Service (ES) provisioning is identified as the solution to deal with the sustainability challenges of biomass use. Agroforestry systems, integrating energy crops in farmlands, and in particular short rotation silvoarable systems (crops and short rotation trees integration), are identified as promising strategies for sustainable biomass production while enhancing ES provisioning and agricultural lands' resilience. The subsequent research questions explore Life Cycle Assessment (LCA) results comparing different alternatives for methanol production. Silvoarable systems show favourable climate change and fossil fuel depletion performance when compared to natural gas-based methanol, but other impact categories do not offer significant advantages due to higher electricity consumption. The use of forest residues for methanol production performed better than the silvoarable alternative in most of the impact categories, but when more productive silvoarable plantations are considered or non-local sourcing of forest residues is necessary, silvoarable systems are as good or better than these systems. The alternative of using marginal lands for short rotation production had a lower performance compared with the silvoarable system mainly due to the lower productivity of these systems, however, this could also be considered as good feedstock for methanol production particularly if these are grown in floodplains to improve the yields of the system. Considerations of the aviation industry's environmental impact and supply chain are briefly included. While bio-based composites offer carbon emissions savings, these reductions are minimal compared to the overall aviation emissions. Cost considerations pose challenges, with bio-methanol alternatives currently having higher production costs. Suggestions include CO2 emissions taxes, subsidies, and optimized supply chain processes to bridge this gap. In conclusion, this research provides valuable insights into the potential of short-rotation silvoarable systems as sustainable biomass feedstock providers for composite manufacturing. While the LCA results demonstrate promising environmental advantages, the results are limited to the narrow scope of this study. Therefore, further exploring and studying these systems is required if these systems are aimed to be considered future biomass providers. The findings offer Airbus and other industries an opportunity to embrace sustainable bioeconomy models, contributing to environmental footprint mitigation and restoration of equilibrium with natural systems.

With the increasing focus from policymakers to a circular economy, assessing the environmental impacts of circular products is becoming more important. In this thesis a Life Cycle Assessment of the new circular composite Re-plex is performed. The Re-plex can be used as building material. Re-plex is produced from Kaumera Nereda® Gum recovered from Nereda® wastewater sludge, and Recell® cellulose recovered from wastewater. Re-plex is still in the developmental phase, this LCA is performed to aid engineers to reduce the environmental impacts of the Re-plex composite. A comparative LCA is performed in which the current Re-plex production is compared to Fire-retardant Medium Density Fibreboard (FR-MDF) with the ILCD impact assessment family. The functional unit is 1 year of 1m2 use of interior finishing material. The Re-plex has a better characterisation result in the impact category; Human Health (HH), respiratory effects, inorganics. The FR-MDF has better characterisation results in the impact categories; Climate change; Ecosystem Quality (EQ), acidification; EQ, freshwater ecotoxicity; EQ, freshwater eutrophication; EQ ionizing radiation; EQ, marine eutrophication; EQ, marine eutrophication; Human Health (HH), carcinogenic effects; HH, ionizing radiation; HH, non-carcinogenic effects; HH, ozone layer depletion; HH, photochemical ozone creation; Resources (RS), land use; and RS, mineral, fossils and renewables. Scenarios are developed to improve the environmental performance of the Re-plex production. Increasing the amount of cellulose in Re-plex does not seem to improve the environmental performance. Three scenarios do improve the environmental performance; Replacing citric acid by succinic acid; improving the energy efficiency; and drying the Kaumera Gum before transport. These three improvements are combined in the new Re-plex scenario. The improved scenario has better characterisation results than FR-MDF in the ten impact categories; Climate change; EQ, acidification; EQ, freshwater ecotoxicity; EQ, freshwater eutrophication; EQ, marine eutrophication; EQ, marine eutrophication; HH, carcinogenic effects; HH, non-carcinogenic effects; HH, photochemical ozone creation; and HH, respiratory effects, inorganics. FR-MDF scores better in the five impact categories; EQ ionizing radiation; HH, ionizing radiation; HH, ozone layer depletion; RS, land use; and RS, mineral, fossils and renewables. Engineers working on Re-plex are advised to change the use of citric acid to a better environmentally performing material. The environmental benefit of changing this material will add more value to a Re-plex product than the lower price when using citric acid. Further, the focus should be on improving the energy efficiency of Re-plex production and realising a lifetime of Re-plex of 32 years, similar to MDF. If these improvements can be realised, Re-plex has a better environmental performance than FR-MDF.