Feasibility analysis of reverse osmosis desalination driven by a solar pond in Mediterranean and semi-arid climates

Solar desalination is emerging as a sustainable solution for water shortage in countries having limited access to conventional energy resources. This paper proposes an autonomous desalination system fully powered by solar energy. This system mainly consists of a salt gradient solar pond coupled to an organic Rankine cycle that drives the pumps of a reverse osmosis desalination unit. For each of these three components, a theoretical model is elaborated, and validated with numerical and/or experimental data. Then, each model is combined with a genetic algorithm to determine the optimal design and operating parameters. The optimization tests revealed that the hybrid pressure vessel can produce fresh water at a salinity of 376.6 mg/l with a specific energy consumption of about 2.1 kWh/m(3). A recuperative organic Rankine cycle was optimized to supply the desalination unit, composed of 31 hybrid pressure vessels and 3 pressure exchanger devices, with 0.28 MW of electric power with an exergy efficiency around 54%. In addition, the results predicted that the solar pond land required to run the desalination unit at a daily drinking water production of about 2380.8 m(3) is almost 33.6% smaller in the semi-arid climate compared to the Mediterranean one. The designed desalination plant can supply drinking water over 73.3% of the year, 61.2% of whom without interruption, in semi-arid climate compared to only 50% in the Mediterranean one. The discussion of the results includes some technics suggested to enhance the feasibility of the current plant.