Production of ethanol, xylitol and antioxidants in a biorefinery from olive tree wastes: process economics, carbon footprint and water consumption

Abstract

Abstract This work focuses on the evaluation of the economic performance and carbon and water-related environmental impacts of a biorefinery scheme using olive tree pruning wastes as feedstock. The considered process is based on a multiproduct biorefinery producing 0.66 m 3 /h of ethanol, 114 kg/h of xylitol and 144.4 kg/h of antioxidants valorising both the cellulose/hemicellulose and the extractives fraction. The plant is not energetically self-sufficient (even considering the combined heat and power production from the combustion of the waste solids fraction) requiring a supply of natural gas. Nonetheless, the plant shows a positive investment balance with a net present value of 11.56 M€ in a 20-year period being the most important product the antioxidant which represent 66.2 % of total revenues. In addition, the biorefinery also shows a better environmental profile in comparison to the business-as-usual production of ethanol, xylitol and antioxidant.