| Abstract |
Industries across the world are making a transition from fossil resources to renewable biological feedstock for the production of chemicals, fuels, and materials, as a strategy to promote sustainable development and economic growth. However, limited biomass availability can halt the expansion of bio-based sectors, unless alternative raw materials are employed and cascading uses are implemented on a large scale. Key Enabling Technologies (KETs) can contribute to feedstock diversification and improved biomass conversion efficiencies along supply chains, although concerns arise about their actual viability and competitiveness. A systematic review of Life Cycle Assessments (LCAs) and related process-based approaches is carried out to evaluate the sustainability of advanced bio-based technologies, defined as those that use either non-food feedstock or circularity principles -or both- for delivering diverse products. A classification scheme is proposed to categorise KETs based on the feedstock employed (plant residues and perennials, designer crops, algae, or biological waste) or the underlying technological configuration (enzyme/microbial assisted processing or biorefineries). Results show that producing biofuels and biochemicals from perennial plants, lignocellulosic residues and algae has advantages in terms of greenhouse gas emissions relative to their fossil counterparts, while trade-offs occur with other environmental impacts and sustainability dimensions. Cradle-to-cradle systems can deliver additional sustainability gains, but their implementation poses technical and socio-political challenges. Further harmonisation of LCA methodologies is desirable to compare KETs in different sectoral, geographical and policy contexts. In spite of the diversity of outcomes and approaches, this review provides an overview of advanced bio-based technologies, while shedding light on the often overestimated sustainability benefits of the bioeconomy. |