The generation of electric energy by the sugarcane sector stands much below its potential. Using ﬁve case studies with São Paulo plants, this article aims to identify the obstacles to the expansion of the electric energy commercialization by the sugarcane sector. High costs associated to the commercialization of electric energy - in commercialization of excesses, and in the acquisition for proper consumption – are the most reasonable explanation for the self-sufﬁciency in the production of electric power by the sugarcane sector, an allied energy to the small generation of excesses of energy for commercialization. Out of the ﬁve plants studied, three plants that commercialize energy excesses make it as part of a strategy of anticipation of the future need of self-sufﬁciency. Having associated costs for sale of excesses of electric energy, they do not have incentives to the use of technologies of higher energy efﬁciency. The public policy directed to the expansion of energy excesses must turn toward the reduction of the costs associated to the commercialization thereof. Particularly interesting it would be to increase the volume of free consumers and to support the commercialization between these and the co-generators of energy.