This project studies the possibility of using the thermodynamic cycles of Rankine, Kalina, and the combined cycle of Rankine-Kalina for the production of electric energy at a sustainable production plant of micro algae and animal feed. In the present work, heat source and sink were characterized by, respectively, the exhaust gases from the combustion of methane produced from the organic waste and ambienttemperature water. The calculation of the necessary quantity of organic waste was also carried out. After the cycles were defined, the thermodynamic properties were calculated with the EES program and the results, in terms of produced potential and efficiency, were compared. An optimization was realized for each of the three cycles in order to define the best value of the parameters of the cycles as pressure of the turbine work and the temperature of the work/project fluid saturation. The possibility of using a combined cycle was analyzed, taking advantage of the heat of the evaporator rejection of the Rankine cycle in order to feed a Kalina cycle.