Designing an olive tree pruning biorefinery for the production of bioethanol, xylitol and antioxidants: a techno-economic assessment

Abstract

Olive tree crops, extensively cultivated in Southern European countries, yield large amounts of olive tree pruning (OTP) biomass. This could be used within the framework of a bio-based economy that maximizes the utilization of biomass resources in a sustainable way. In the present work, the techno-economic feasibility of an OTP-based integrated biorefinery is evaluated by the process simulation software Aspen Plus, while the process is aimed at the production of ethanol, xylitol, antioxidants and electricity. Overall, the proposed plant could perform economically, and it is self-sufficient from an energy resource point of view. The plant as designed yields around 109 l of ethanol, 27 kg of xylitol and 43 kg of antioxidants per ton of OTP biomass, with an estimated production cost of 0.24 € l−1, 1.48 € kg−1 and 5.12 € kg−1, respectively. In a 10-year period, the economic profitability of the biorefinery plant is within a positive investment balance, with a net present value (NPV) of 32.1 M€ and a payback period of 5–6 years. These figures point out the opportunities for placing in the market several OTP-based products. Based on these data, the construction of small-scale OTP-based lignocellulosic biorefineries seems to be a realistic scenario.