Evaluation of energy demand and the sustainability of different bioethanol production processes from sugar beet

Abstract

In this study, different bioethanol production processes from sugar beet were analyzed to improve energy input/output ratio and process sustainability. As inputs for fermentative bioethanol production, sugar factory can use some intermediate products [e.g. raw sugar juice (≈15–18% sugar) or concentrated sugar syrup (≈65–67% sugar)] or by-products (e.g. molasses ≈50% sugar). From energetic point of view, the main energy consumption operations in bioethanol production are: sugar extraction from sugar beet chips, sugar juice concentration by evaporation, ethanol distillation as well as distillers mash concentration and beet chips drying. In decision-making processes for different bioethanol production processes from sugar beet the concept of ecological footprint was used. Results of ecological footprint pointed out that energy demand and sustainability of standard process can be significantly improved by introduction of new technologies, i.e. simultaneous sugar extraction, pulp fermentation and product recovery (SEFPR) combined with biogas production from fermentation residues.