Prospective LCA of future pathways for used cooking oil valorisation: advancing renewable energy and sustainable materials

This study aims to evaluate the environmental performance of different valorisation pathways for used cooking oil (UCO). By applying prospective life cycle assessment (pLCA), conventional energy-based routes, such as biodiesel production, cogeneration, and incineration; were compared with novel materials routes such as bioplastic production using PRETENACC technology (TRL = 5). The analysis focuses on identifying the most environmentally favourable long-term option, emphasizing how increasing the market share of bioplastics could shape future UCO recovery strategies. As the first step of the pLCA, more than 30 parameters related to UCO valorization were identified together with stakeholders with expertise in political, environmental, social, technological, economic and legal (PESTEL) fields. These were used to generate five future scenarios for 2030, 2040 and 2050. Life cycle inventories were developed using experimental and literature data on bioplastics, as well as data from the literature on energy pathways, covering the system boundaries from cradle to grave. The background processes were futurised with Ecoinvent 3.9.1 and scenarios based on IMAGE (SSP2-base and SSP2-RCP2.6). Environmental impacts were quantified using the intermediate categories of ReCiPe 2016, supplemented with indicators of the physical effects of microplastics on terrestrial and aquatic biota. The pLCA results show that scenario 1 (0% market share for bioplastics) has the lowest initial impacts (2030). Nevertheless, over time (2040 and 2050), only the environmental burden of bioplastics decreases, driven by cleaner electricity production and better waste sorting. Climate change impacts are largely influenced by bioplastics production and end-of-life (EoL) management, with mixed waste disposal accounting for up to 26% of the total impact in 2030, decreasing towards 2050. Terrestrial acidification is dominated by the bioplastics production. Particle formation reflects combustion-related trends, while microplastic impacts depend on poor management, which mainly affects marine environments as the final sink. Energy recovery pathways show limited potential for improvement, while bioplastics offer increasing long-term environmental benefits if appropriate EoL pathways are followed. This study demonstrates that while energy recovery pathways, such as biodiesel, cogeneration, and incineration, contribute marginally to long-term environmental improvements, material valorisation through bioplastics offers a promising and more sustainable UCO management route. Environmental performance of bioplastics is highly dependent on EoL management and the polymer composition. Enhancing waste sorting practices and adopting lower-impact polymer blends are critical to maximizing benefits, enabling a significant reduction in the impacts associated with bioplastics. pLCA compares future environmental impacts of used cooking oil valorisation routes Bioplastics may have lower impacts if their waste is properly managed Biodiesel pathways limited by combustion emissions across all time horizons The impacts of energy valorisation routes persist over time Five scenarios developed integrating technology, policy and stakeholder input