Integração energética da produção de biogás em biorrefinarias de cana-de-açúcar integradas de 1ª e 2ª geração

Abstract

The ethanol production process is commonly performed in Brazil by extracting the sugarcane juice for fermentation and distillation, while the bagasse is burned in boilers for energy cogeneration. Although these processes generally utilize all the available biomass, it also generates large amount of residue, known as stillage or vinasse, which when used in fertigation is responsible for many environmental problems. Moreover, the need to expand biofuel production generates a considerable problem regarding the land use for food production. In this sense, the production of second generation (2G) ethanol is an alternative to increase bioethanol productivity while maintaining the same area of planted ​​cane, but bringing the problem of the vinasse generation increase. In view of the challenges created around this issue, a model was developed considering the biological anaerobic treatment of vinasse for the production of methane to be used as a source of energy in an autonomous plant ethanol. The bagasse supposed to be burned for this purpose was then conducted to produce 2G ethanol, increasing the productivity of the fuel. Using the Solver tool of Excel software, it was possible to obtain with this model up to 23 L t-1cane 2G ethanol without compromising the energy self-sufficiency of the plant, so that 9.82 m³ t-1cane of methane produced by digestion allowed liberation of 17% of bagasse from cogeneration to produce this fuel. Thus, it would be possible to obtain an annual income of up to R $ 58 mi. In addition to increased productivity, this model also foresee the reduction of environmental impacts caused by the application of vinasse in the soil, such as preventing emissions of around 33.000 tN2O season-1, and the generation of economic value by selling products and carbon credits that could fund the operation of biodigestion in the unit.