variavel0=<b>Mauricio Colombo</b> - macolombo@herrera.unt.edu.ar Universidad Nacional de Tucuman
<b>María Rosa Hernández</b> - rhernandez@herrera.unt.edu.ar Universidad Nacional de Tucuman
<b>José Luz Silveira</b> - joseluz@feg.unesp.br UNESP
<b>Abstract.</b> The development of new techniques that allow analysis and optimization of energy systems is indispensable in a world with finite natural resources and growing demand of electrical energy for development countries. Cogeneration is used in sugar plants,  since it requires steam production and electric power. The method used to evaluate cogeneration alternatives combines Second Law of Thermodynamics, through an exergy approach, with the economic evaluation of the thermal system. In this work a powerful tool is developed to implement an optimization superestructure that contemplates all the possible cases outlined according to exergetic cost functions defined by the functional diagram. Also, the present work shows the need for parametric sensitivity analysis of selected optimization variables
<b>Keywords.</b> cogeneration, optimization, functional diagrams, sugar plants.