Energy cost comparison between MSF, MED and SWRO: Case studies for dual purpose plants

Energy cost comparison between MSF, MED and SWRO has been conducted. In order to investigate energy consumption differences when combined with a simple cycle Oil-Fired Power Plant (OFPP) or a Combined Cycle Power Plant (CCPP), Yanbu Ph.3 and Ras Al-Khair Ph.1 power and water cogeneration projects are considered as practical heat and mass balance references. With the net power production of 2708.5 MW and the total water production of 124.54 MIGD, the fuel energy differences due to desalination are compared. By calculating the fuel energy requirement for desalination from a cogeneration cycle itself, some controversial issues including evaluating electricity and steam could be avoided. Results show that the required fuel energies for desalination are less by 11-49% when combined with CCPP than with OFPP, owing to the higher efficiency of the combined cycle. Thermal desalination benefits more greatly from the combined cycle's higher efficiency due to a lowered steam value. While SWRO shows a better fuel energy efficiency for most of the studied regime, high Performance Ratio (PR) MEDs combined with CCPP could be a similar energy efficient option if PR is 16.5-19.3, compared to SWRO with CCPP.