Thermoeconomic analysis of electricity cogeneration of sugarcane origin

Most Brazilian sugar/alcohol industries are energy self-sufficient and, in the State of Sao Paulo, some of them even export electricity surplus to local utilities. However, despite the huge potential of electricity surplus to be generated, there are still difficulties to be solved. One of the main problems is the sale price of electricity. Despite the advantages of sugarcane-origin electricity both for the electric sector and alcohol industries, they do not agree about the sale price and most industries are not interested in selling electricity, considering the price offered by local utilities too low. This paper evaluates the cost of the electricity surplus for real plants, using thermoeconomic analysis. Different cogeneration systems are considered and the corresponding electricity costs are evaluated and compared to the current electricity marginal cost of Southeast Brazil. From obtained results, mechanisms are proposed to improve the existing cogeneration program, aiming to accomplish its initial objectives. (author)