How could waste-based bioplastics improve the environmental footprint of the EU plastic packaging sector? A life cycle and planetary boundaries-based assessment

The transition toward a sustainable plastics system is essential to address the triple planetary crisis of climate change, biodiversity loss, and pollution. It requires alternatives to fossil-based polymers that reduce environmental impacts while remaining compatible with existing packaging functions and infrastructure. Bio-based plastics, which currently account for less than 1% of global plastics production, are increasingly promoted as such alternatives. While most existing production relies on first-generation (1G) feedstocks such as agricultural crops, bio-based plastics derived from second-generation (2G) feedstocks (e.g., agricultural residues, food waste) have gained increasing attention in recent years. These materials can reduce land use, avoid competition with food production, and support circular economy strategies by valorizing waste streams. However, despite this potential, significant knowledge gaps remain regarding their environmental performance, data availability, scalability, and integration into existing value chains. This thesis evaluated the environmental sustainability of 2G bioplastics and their substitution potential as alternatives to fossil-based plastics and 1G bioplastics in the EU plastic packaging sector. Importantly, it moved beyond conventional “relative” comparisons (e.g., impacts per kilogram of polymer) and instead assessed whether these solutions are “absolutely sustainable”, meaning whether the sector operates within the Earth’s ecological limits. To do so, the study applied the Planetary Boundaries framework, which defines a “safe operating space for humanity” by setting quantitative limits for key environmental pressures such as Climate Change. To achieve this, the study developed a multi-step and replicable methodological framework combining: (1) a literature review-based mapping of waste-to-biopolymer conversion pathways; (2) a systematic literature review and metadata analysis of Life Cycle Assessment (LCA) studies; and (3) an Absolute Environmental Sustainability Assessment (AESA) of sector-level substitution scenarios, linking LCA results to Planetary Boundaries. First, a structured mapping of the literature identified existing waste-to-biopolymer conversion pathways, including 2G feedstock types, extraction methods, and resulting polymer families. A Multi-Criteria Decision Analysis (MCDA) then prioritized polymers based on several aspects, including economic relevance, packaging applicability, and environmental considerations using the most recent market data. This step led to the selection of five key bio-based polymers for further analysis. Second, a systematic literature review identified 35 LCA case studies related to the prioritized waste-derived biopolymers. A metadata analysis harmonized the reported environmental results across studies and highlighted key methodological drivers affecting LCA results, including feedstock type, system boundaries (e.g., cradle-to-gate vs. cradle-to-grave), alloca