Life cycle assessment of an integrated xylitol biorefinery with value-added co-products

Abstract

PurposeThis manuscript comprises a detailed life cycle assessment of an integrated xylitol biorefinery with value-added co-products. The biorefinery utilizes wheat straw as lignocellulosic feedstock and employs bio-based processes to produce xylitol as the main product and succinic acid as a co-product. The biorefinery was conceptually designed in an optimization-based framework and assessed through a techno-economic analysis published in the authors’ prior publications.MethodsThe goal is to determine the environmental impacts of the xylitol biorefinery and to compare the effects of bio-based production in the biorefinery to the current chemical production processes of xylitol. The scope is set as cradle-to-gate to allow a direct comparison of the chemical processes. The presented life cycle assessment was performed according to the standardized ISO procedure.ResultsThe reference unit is related to the feedstock as multiple products are produced, and an economic allocation is chosen. The life cycle inventory is based on secondary data from process simulations stemming from earlier published work. The impact assessment is performed with the ReCiPe 2016 Midpoint H V1.05 method and the IMPACT2002 + method since the available data of the life cycle assessment for the chemical processes was obtained with the latter. The characterization of the impacts shows high impacts for the terrestrial, marine, and human carcinogenic toxicity impact categories and a comparatively low impact on global warming.ConclusionsThe results are interpreted and assessed with an additional sensitivity analysis. Furthermore, the results are compared with the two chemical production processes. The comparison shows lower impacts of the xylitol biorefinery compared to the standard chemical production process but slightly higher impacts compared to the proprietary production process of DuPont, which employs a high level of process integration. These results are further discussed and contextualized.