Exergy and Environmental Analysis of a Polygeneration System of Alcohol Industry

An analyze of three case studies from environmental and energy view point, those case studies are polygeneration system, A first study is referred to a conventional distillery that produces ethanol and surplus electricity, the second one, in addition to ethanol and electricity products, also produces second generation bioethanol (2G) from sugarcane bagasse. A third case study refers to an installation producing surplus electricity, bioethanol (2G) from bagasse and bioethanol from cane juice, as well as fodder yeast from vinasses (distillery residue). After defining each study, an exergetic analysis and calculated performance indicators were made to determine best case study. A Life Cycle Analysis to verify the environmental performance of each system complemented the study. Results indicated that case study 3 presented best energy performance, with an exergetic efficiency of 45.03%, having as advantage fodder yeast for cattle feeding. From environmental point of view land occupation by agriculture remains main environmental impact for all three case studies. This paper presents an alternative for products diversification of an autonomous distillery, combining second generation ethanol and use of vinasses (distillery residue) as raw material for fodder yeasts bioproduction, a feeding cattle protein supplement, inducing also a significant reduction of vinasses contamination potential.