Sustainable production of xylo-oligosaccharides: A comparative environmental life cycle and techno-economic analysis

This study evaluates the economic and environmental performance of two biorefinery scenarios producing xylo-oligosaccharide (XOS) prebiotics (Degree of Polymerization ≤3) from oat bran. The configurations leverage the lignocellulosic feedstock in two cases: one producing combined microfiber and lignin oil (CML) and the other generating combined heat and power (CHP). A detailed ASPEN model established mass and energy balances for a plant processing 89.45 metric tons (mt) of oat bran per day. These outputs were used for both a life cycle assessment (LCA) and techno-economic analysis (TEA). The LCA results show that the CHP process achieves lower net annual CO₂e emissions of 350 mt compared to the CML process emissions of 168,460 mt, due to the production and use of green electricity and steam in the CHP scenario. The TEA results show that the CHP scenario requires lower fixed capital investment and, despite a slightly lower internal rate of return and longer payback period, offers a competitive net present value relative to the CML scenario. Drawing on both LCA and TEA findings, the marginal abatement cost for CO₂ in using the CHP process relative to the CML process was determined to be $2.18 per mt, which drops to $0.42 per mt when carbon credits are considered, significantly lower than current market prices for carbon. Overall, using green electricity and steam in the CHP scenario improved all of the environmental impacts measured in this study while remaining economically comparable to the CML scenario.