This study is to analyze how to extend the sugar plants by a polygeneration technology to produce sugar, bioethanol, biogas and bioelectricity. The possibility of selling the bioelectricity to the national grid in Brazil is also investigated through optimizing the energy production at an industrial plant. The viability of the generation rates for renewable energy proposed by the regulatory bodies within the Brazilian electricity sector is analyzed. The plant's short-term planning was obtained by applying non-trivial optimal solutions that allow officials to choose the best alternative for planning production employing the most economical combinations of sugar, bioethanol, biogas, and electricity. We calculated the cost of exporting electricity to the electrical grid from January 2008 to December 2009, concluding that the spot market prices were too low to stimulate the sale of the bioelectricity to the electrical grid. Moreover, the remuneration guaranteed by the Brazilian Program of Incentives for Renewable Resources (PROINFA) was not sufficient to stimulate the sale of the bioelectricity. However, the price set by the Brazilian Electrical Regulating Agency (ANEEL) in the 2009 auction was sufficient to support exporting electricity for all the months except December 2009. (C) 2011 Elsevier Ltd. All rights reserved.