Waste heat recovery from power plants for solar desalination: a mechanical power engineering approach

Abstract This study presents a thermal design of solar stills by utilizing waste heat from thermal power plant cooling water. The main objective is to enhance energy recovery with solar still technology and minimize mechanical energy consumption. This paper introduces an innovation approach to desalinate the seawater by the free energy from the cooling water of power plants. This is considered a waste energy besides its harmful effect to the environment. This could be achieved by transferring part of this water to solar stills instead of throwing it into the sea and hence reduce its thermal pollution. Ain Sokhna Thermal Power plant with capacity 1,300 MW with thermal discharge of 45 m 3 /s and temperature difference 10 ̊C is taken as study case. The methodology is represented as follows. design the desalination plant by using solar stills, and estimate both; the number of solar stills units that are based on the amount of cooling water coming out of the power plant and the required land area. Part of the power plant area was taken to build blocks for solar distillation units by using part of the power plant’s cooling water. A water pipeline was designed with openings nozzles to feed the water at each row in the blocks. The total energy along the path of the feed pipeline was calculated. The ground elevation model found in nature was exploited to push water freely without the need for a lifting pump to save energy for a distance of 839 m, i.e. a distance of more than three quarters of the total length of the line, with the need for a pump of 0.584 (kw) only at the end of the line. The reduction in Green Hose Gases GHG emissions is estimated. Comparison between the common process of seawater desalination and the current study were presented. Production (212.6 m 3 /day), land area (50,344 m 2 ), number of units (12,505), GHG reduction (44.73 tons CO 2 /year vs MSF, 7.16 tons CO 2 /year vs RO), and LCOW ($0.657/m 3 ).