Análise técnico-econômica para tecnologias de disposição da vinhaça

Abstract

This work presents a techno-economic feasibility assessment of different alternatives for vinasse disposal, all based on simulations performed using the DWSim software, version 7.1.2. Currently, vinasse is predominantly used untreated for fertigation of sugarcane. However, there are alternatives that can reduce transportation costs, and the environmental impact caused by the disposal of untreated vinasse, in addition to adding value through electricity generation and decarbonization credits. The different alternatives evaluated include vinasse concentration at 3, 4, 5, and 6 times its volume, where each concentration level was considered as a distinct alternative. Additionally, fresh vinasse biodigestion associated with cogeneration and concentration (3x, 4x, 5x, and 6x) followed by biodigestion and cogeneration were evaluated. The objective of the evaluation was to determine whether any of these alternatives would be economically viable, using payback time as criteria, considering capital and operational costs as well as the associated revenues. The analysis also considered sensitivity to commodity and international exchange rate fluctuations. The use of biodigestion and cogeneration is only viable when the vinasse is concentrated, becoming progressively more viable as its volume is reduced, reaching the lowest payback time of 8.7 years. The use of concentration alone is more viable, as the primary source of revenue from these alternatives comes from reducing the cost of transporting vinasse by tanker trucks. Similarly, the payback time is gradually reduced as vinasse concentration increases, reaching a value of 8.1 years when concentrated 6x. The use of untreated vinasse for biodigestion is unfeasible, with no return on investment due to the high implementation costs caused by the large equipment sizes required.