Transforming lignocellulosic residues into bio-lactic and bio-succinic acid: A comparative sustainability analysis using a hybrid life cycle approach

Lactic and succinic acid (LA and SA) are two biobased chemicals with applications including bioplastics such as PLA and PBS. Due to this interest, this study evaluates the sustainability of LA and SA produced from two abundant agroforestry wastes in two specific regions of Spain: olive tree pruning (OTP) from Andalusia and eucalyptus residues (ER) from Galicia. The sustainability assessment integrates well-established methodologies for each dimension of sustainability: Hybrid Life Cycle Assessment for environmental (GWP 100 , water use and terrestrial acidification), Profitability Analysis for economic (minimum selling price, ROI, gross margin, net revenues, and payback period) and input-output model for social (job creation, GVA and induced economic impact). These indicators have been aggregated into a total sustainability composite indicator to rank the four scenarios analysed. The results demonstrate that the ER LA produced in Galicia is the most sustainable option. This process would produce 56.30 kt LA/y with a market-competitive price of 1.43 €/kg LA, a ROI of 8.54 %, and a payback period of 14.83 years. Additionally, it has been estimated to reduce the unemployment rate of Galicia by 0.67 % and contribute 32.56 € per capita to the GVA. From an environmental perspective, the biorefinery has produced values of 5.43 kg CO 2 eq./kg LA for GWP 100 , 0.186 m 3 /kg LA for water use, and 3.36 10 −2 kg SO 2 eq./kg LA have been obtained. These results are slightly less favourable compared to fossil LA due to the current immaturity of lignocellulosic biorefinery processes and underscore the necessity for further research and optimisation.