Scenario-based life cycle assessment of cellulose nanocrystals production from agro-industrial by-products in 2040

Cellulose nanocrystals (CNC) are versatile nanomaterials of exceptional strength with many applications ranging from packaging to medical uses. While typically produced from Kraft pulp, novel experimental pathways have been developed to obtain CNC from by-products; however, their environmental impacts have not been assessed at a future industrial scale. In this article, a prospective life cycle assessment (pLCA) is conducted for CNC production in two routes coupling acetosolv pulping and acid hydrolysis, with alternative feedstocks: mango seed shells (MSS) and oil palm mesocarp fibers (OPMF). The study is conducted from cradle to gate for 1 kg CNC (solids, in suspension) and follows an adapted version of the “SIMPL” approach for scenario-based prospective life cycle inventory (pLCI) modeling, while incorporating a pLCI database for 2040 (based on the “premise” framework). Upscaling assumptions based on process calculations, extrapolation, and expert advice are integrated into scenarios with consistency checks. Impact assessment covers climate change, freshwater eutrophication, and fossil resource depletion. A current technology (2024) is compared with future (2040) scenarios with varying degrees of technological progress and climate policy ambition. The MSS route consistently outperforms the OPMF route, with climate change impacts of 18.9–79.6 kg CO 2 eq (MSS) vs. 26.1–127.8 kg CO 2 eq (OPMF). However, the MSS route shows higher impacts than Kraft pulp-CNC (11.2 kg CO 2 eq), mainly due to energy-intensive acetosolv solvent recovery. Drastic modifications to the pre-treatments are necessary for MSS-CNC to compete with Kraft pulp-CNC. Insights to reduce CNC impacts and recommendations for upscaling bioprocesses are provided. • Prospective LCA of CNC production based on acetosolv pulping/acid hydrolysis. • Upscaling of lab processes by process calculations, extrapolation & expert advice. • Future background projections for 2040 based on shared socioeconomic pathways. • Solvent recovery energy and chemical inputs are main hotspots. • Oil palm mesocarp route shows higher impacts than mango seed route in all scenarios.