Optimal Design of Integrated Solar Combined Cycle and Desalination Systems

This paper addresses the optimization of dual-purpose desalination plants (DPDPs) for simultaneous generation of electricity and fresh water. The optimization problem is finding the optimal design and operating conditions to meet desired electricity generation and freshwater amount at a minimal total annual cost. The multi-effect distillation (MED) desalination and/or reverse osmosis (RO) processes are the candidates to produce the required freshwater production. Thus, the selection of the desalination process represents a model decision. First, a conventional DPDP is defined and used as the base case. Then, upgrading the optimized conventional DPDP (base case) is investigated by adding a solar collector and keeping unchanged the sizes of the process units of the optimized DPDP. The optimal process configuration is selected from different candidate configurations. For instance, (a) one solar collector/combined cycle/MED; and (b) one or two solar collectors/combined cycle/MED/RO. Two new optimization problems are solved: (a) the optimization of the operating conditions of the entire process to maximize the electricity generation keeping the same fuel consumption, and (b) the optimization of the operating conditions of the entire process to minimize the fuel consumption keeping the same electricity generation. By keeping the same process units obtained for the optimized conventional DPDP and by adding a solar collector, the electricity generation can be increased up to 5.62 MW, and the fuel consumption can be reduced by 2310 ton/yr and thereby 6352 CO2 ton/year.