Study On Reverse Osmosis Seawater Desalination Driven By Wind Energy

Seawater desalination technology has been more and more widely used to solve the problem of water shortage.Reverse osmosis(RO)has become one of the main seawater desalination technologies due to low energy consumption,high modularization degree and great operation flexibility.For coastal areas and islands,the coupling of renewable resources such as wind power with reverse osmosis technology has become a research hotspot due to energy supply problems.However,the intermittency and fluctuation of wind speed would bring great challenges to the application of wind energy in reverse osmosis seawater desalination.According to the instability of wind speed,the reverse osmosis seawater desalination system driven by hybrid wind turbine and diesel generator was designed.Firstly,a mathematical model of reverse osmosis seawater desalination process was established.The reverse osmosis model was in good agreement with the simulation results of commercial membrane system design software.The relative errors of system recovery rates and salt rejections were-3.17%-3.86%and 0.08%-0.55%,respectively.Furthermore,an economic model of water production including initial investment,operation and maintenance costs,and replacement costs of the components of the wind turbine,diesel generator and reverse osmosis system was established.The annual wind speed data of a coastal area was used.Three configurations including wind turbine-reverse osmosis system(WT-RO),diesel generator-reverse osmosis system(DG-RO),and wind turbine-diesel generator-reverse osmosis system(WT-DG-RO)with annual capacity of 182500 m~3were optimized by minimizing the unit water production cost.The lowest water production costs of WT-RO system and DG-RO system were 1.030$/m~3 and 0.940$/m~3,respectively.Compared with WT-RO system,the wind power utilization rate of WT-DG-RO system was increased to 92.2%,and the water production cost was decreased to 0.865$/m~3.Sensitivity analysis was carried out to investigate the influences of the variation of wind speed,seawater salinity,seawater temperature,fuel price,and wind turbine price on the optimal design of WT-DG-RO system.The water production cost of WT-DG-RO system was decreased with the increase of wind speed and seawater temperature,and increased with the increase of seawater salinity,fuel price and wind turbine price.The water production cost was more sensitive to the variation of wind speed.When the variation of wind speed increased from-20%to 20%,the number of wind turbine in WT-DG-RO system was decreased by 2,the annual energy output of DG was decreased,and the water production cost was decreased from 1.068$/m~3 to0.727$/m~3.The model established in this paper can provide theoretical and technical reference for the engineering design of wind power-reverse osmosis coupling system.