Resume

The objective of this study was to evaluate GHG emissions from vinasse distribution channel. The study was developed at Iracema ethanol plant, located in Iracemápolis (SP). GHG samples were taken at six points along the vinasse channel. The GHG analyses were performed by gas chromatography. Emissions rates of CO2 and CH4 were influenced by the physical-chemical composition of the vinasse. Although emission rates of CO2 have been measured, they were not included in total emission calculations, since it is reabsorbed by photosynthesis. N2O emissions were very low, demonstrating that the vinasse does not promote favorable conditions to its formation. Significant variation in CH4 emissions were observed among the sampling points. Mean emissions of CH4 were 386, 1263, 1085, 1163, 1431 and 427 mg CH4-C m-2 h-1, respectively for the points 1, 2, 3, 4, 5, and 6. The lower emission observed in point 1 is associated to high temperature (nearly 48°C) and other channels characteristics, such as soil covering. The higher emission of CH4 between points 2 and 5 is associated to the anaerobic conditions, from the continuous flow of vinasse and high content of organic material in this part of the channel. In the last evaluated point was observed reduction of CH4 emission, which is associated with low amounts of organic material. When converting GHG fluxes in CO2 eq., it was observed that CH4 is responsible for 99.8 % of total emissions from vinasse. Considering the vinasse transportation, it was estimated an emission of 2.23 kg CO2 eq. for each m3 of vinasse. This study confirms the hypothesis that vinasse is an important source of CH4 in ethanol production. However, it is necessary to carry out further studies to support the results and propose strategies to GHG mitigation from the vinasse, aiming environmental sustainability in ethanol production from sugarcane.ഀ ഀ Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)