Predicting the environmental impact of a future nanocellulose production at industrial scale: Application of the life cycle assessment scale-up framework

Abstract

Life cycle assessment (LCA) studies of lab-scale processes come with certain limitations as they are not reflecting e.g. higher efficiencies of large-scale production. To address this, we developed in an earlier manuscript a scale-up framework for chemical processes which is applied in this paper here. Following the framework's five-step procedure on the case of a new nanocellulose production pathway, a scaled-up LCA study for a future production of nanocellulose is performed. The comparison of these LCA results with competing and already commercially produced materials as well as with the lab-scale process demonstrates the usefulness of the whole scale-up procedure. The example shows that the environmental impact per kg of produced nanocellulose yarn can be lowered by a factor of up to 6.5 compared to the laboratory production, reflecting a projected impact that is closer to the values of an actual production plant in case the material will be commercialized. Our results got also better comparable to those of competing materials, showing values that are up to three times smaller than for carbon fibers. Looking into the process, the chosen example of nanocellulose shows a considerable change concerning the relative contributions of the various process steps. While in the lab scale, the enzymatic treatment step - which involved heating for an extended period - was the dominant contributor, this step proved to be negligible in terms of environmental impact at industrial-scale production given that a more efficient and well-insulated reactor is used. The identification of such changes is a major added value of the applied scale-up framework which cannot be achieved with scale-up procedures using a simple, global scaling factor. One of the main purposes of the whole scale-up at such an early stage is to give improvement recommendations. The framework can be considered as being an effective support for eco-design purposes, helping in identifying hotspots for process improvements. It gives a better understanding of the process and shows the practical scalability of the various steps. Overall, it can assist in steering the research of new chemicals and materials more towards an industrial application.