Multiobjective optimization of ultrasound intensified and ionic liquid catalyzed in situ algal biodiesel production considering economic, environmental and safety indicators

Abstract

The current study focuses on the multiobjective optimization of an ultrasound intensified and ionic liquid catalyzed in situ transesterification of wet microalgae for renewable biodiesel production. The process is developed and simulated in Aspen Plus V10 simulator and an excel based multiobjective optimization (EMOO) programme for the elitist non-dominated sorting genetic algorithm-II is used for optimization. Total Annual Cost, i.e. TAC (representing economics), organic waste (representing cleaner production), individual risk, i.e. IR (representing risk to the human capital), and CO2 emission (representing environment) are chosen as the objectives for the constrained optimization of this process. The results show that the TAC reduces with the increase in the generation of organic waste, CO2 emission and IR. This article contemplates and articulates the reasons for the obtained trade-offs between objectives. The quantitative trade-offs between objectives aid to the better decision making about the process design and operation while satisfying economic, environmental and safety concerns. Finally, net flow method (NFM) has been implemented for the identification of best suitable solution in the Pareto-optimal fronts. Simultaneous optimization of all four objectives resulted in the impressive savings in TAC (∼15%), organic waste (∼33%), IR (∼9%), and CO2 emission (∼37%).