Effect of Salt Concentration on Performance of Hydroelectic Power Station due to Osmotic Pressure

This paper presents an experimental study about a possibility of a hydroelectric power station due to osmotic pressure generated between sea water and river water. The experiment is conducted by a newly constructed equipment using a spiral reverse osmotic module with membrane surface area 4.318m2. The equipment can be pressured up to 0.5 MPa to avoid a generation of bubble in pure and salt water channels. Tap water and salt water are used for experiment instead of river water and sea water. On the way of tap water passage, a valve is inserted to generate a loss corresponding to a hydraulic turbine load. Using a pump, salt water is forced to circulate and its flow rate is variable. The flow rate of tap water and the pressure difference between the valve inlet and outlet are measured with varying salt concentration from 0.1wt% to 0.6wt% and salt water flow rate from 3.5 1/min to 5.01/min. In these experiments we can obtain a maximum output about 0.86W at salt concentration 0.6wt%. From these results, we had a confidence to construct the hydraulic power station utilizing osmotic pressure.