Theoretical analysis of a reverse osmosis desalination system driven by solar-powered organic rankine cycle and wind energy

The utilization of renewable energy for desalination can solve the problems of energy crisis and fresh water shortage. In this study, a reverse osmosis (RO) desalination system driven by solar-powered organic Rankine cycle (ORC) system and wind energy is proposed to provide power to drive reverse osmosis desalination unit, which is different from the current desalination system driven by only single energy source. In order to ensure the continuous production of fresh water, energy storage subsystem for both solar and wind energy is employed. A mathematical model based on several assumptions is established to simulate the whole system which mainly contains the solar collector subsystem, ORC subsystem, wind power subsystem and RO desalination subsystem. The sensitive analysis of some key parameters, namely turbine inlet pressure, condenser temperature of ORC, feed water pressure and the salinity of fresh water is conducted to determine the relationship between parameters and fresh water output. The RO desalination system driven by solar-powered ORC system and wind energy could increase the produced fresh water than the system with only solar energy. The results show that there is an optimal turbine inlet pressure under given conditions enabling both the daily net work of ORC and daily fresh water to reach maximum values. The condenser temperature has a significant negative effect on the output of daily net work of ORC and daily fresh water. With the raise of feed water pressure, the output of fresh water and the required membrane area would both decrease. The fresh water output is also sensitive to the salinity of fresh water, while the required membrane area is less sensitive to it.