In this study a conventional and an improved biodiesel production plants, have been simulated in Aspen Plus V8.2. Improved process converts waste cooking oil using a reactive distillation catalyzed by a heterogeneous catalyst in which catalyst removal and neutralization units are not necessary. Using pinch technology and exergoeconoic analysis, exergy destruction of each process are calculated and the best configuration in order to integrate biodiesel production process with a combined cycle power plant is presented. The results show that the produced electricity in the modified process is less expensive. Exergy destruction to generated power ratio and the net power generation in the conventional process are equal to 1.59 and 17936.6 kW, respectively, and the corresponding values for the modified process are 1.57 and 18346.1 kW, respectively. The costs of electricity are 19.145 $/GJ and 16.91 $/GJ for the conventional and improved cases, respectively. (C) 2018 Elsevier Ltd. All rights reserved.