Vinasse composition varies throughout the year, which may affect methane production. To assess the effects of the chemical oxygen demand (COD) on methane yield, we fed a reactor with increasing organic loading rates ranging from 1.15 to 4.56 g COD l⁻¹ day⁻¹. In the second part of this study, we compared two scenarios for the state of Sao Paulo: 1) average vinasse COD; 2) ideal vinasse COD (38.8 g l⁻¹). We found that the maximum methane yield was obtained at an OLR of 2.66, equivalent to a COD of 38.8 g l⁻¹, and could increase the sugarcane mill energy production by 15.6 %. Considering the state of Sao Pauo, if all the vinasse was used to produce biogas, 3.9 million tons CO_2eq (CBIOs) emission would be avoided yearly. Concentrating all the vinasse to the ideal COD would increase it by 3.2 %. Therefore, vinasse concentration would have little effects on a state-scale.