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.