Cost optimization of a combined power and water desalination plant with exergetic, environment and reliability consideration

The present study deals with the multi-objective optimization for designing a combined gas turbine and multi stage flash desalination plant. In optimization approach, the exergetic, economic and environmental aspects have been considered, simultaneously. In order to achieve the optimal design, Multi-objective genetic algorithm (MOGA) is applied as a suitable optimization technique. The thermoenvironomic objective function is obtained by integrating the environmental impacts and thermoeconomic objective. By applying the optimization approach, this objective function is minimized, whereas system exergy efficiency is maximized. Moreover, equipment reliability using the state-space and the continuous Markov method is incorporated in optimization results to improve the products' cost values. The optimization results show that the cost of products and environmental cost impact are reduced by 13.4% and 53.4%, respectively, whereas a 14.8% increase happens in total exergy efficiency. Therefore, improvement in all objectives has been achieved using the optimization process, although the power and water productions have not changed much. Additionally, the sensitivity analysis shows the relationship between the fuel cost, pollution damage cost and the objective functions.

► Multi-objective optimization approach has been implemented in the dual-purpose system.
► Objective functions based on the economic, environmental and exergetic analyses are optimized.
► Markov method is incorporated with the optimization results to improve the cost values.
► Improvement in all objectives is achieved using the optimization process.
► Sensitivity analysis shows that the fuel cost has affected more than the pollution damage cost on the optimization results.