Life cycle sustainability assessment of bioderived advanced materials: A state-of-the-art Review

Bioderived advanced materials possess unique functional properties together with a potential to improve environmental sustainability. This study conducts a critical review of literature on life cycle sustainability assessment (LCSA) of biobased higher-value products with emphasis on bioderived advanced materials including nanocelluloses (cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs)), and carbon materials (lignin carbon fibre (LCF) and hard carbons (HCs)). The environmental impact of CNCs production from Kraft and dissolving pulp via sulfuric acid hydrolysis is significantly influenced by the end-of-life (EoL) management of sulfuric acid either via recycling or neutralisation with sodium hydroxide. This highlights trade-offs and the need for more sustainable EoL options. Likewise, the production of CNFs using Kraft, dissolving and sulfite pulp via 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidation followed by mechanical homogenisation or sonication indicates higher environmental impact compared with enzymatic hydrolysis. Sustainability of LCF is significantly influenced by the lignin recovery and fabrication technique, thus low-cost sustainable solvents and pathways for LCF production should be prioritised. Existing studies indicate the advantages of HCs production via hydrothermal carbonisation (HTC). However, the sustainability performance of HC is highly influenced by the carbon yield and electrochemical performance, therefore, a comprehensive optimisation of the operating variables is crucial for advancing the sustainability and development of bioderived HCs for energy applications. Significant methodological disparities were observed among the reviewed studies, leading to variations in assessment outcomes. Economic and environmental assessments are frequently presented as standalone results even for combined assessments, which further stresses the inherent heterogeneity across assessment tools.