Model for evaluating the electric power output of pressure retarded osmosis generation plants

Abstract

In this work a mathematical model is assembled to evaluate the electric complex power and electric current output of pressure retarded osmosis (PRO)-based generation plants. Unlike other works already reported in the literature, the assembled model allows performing that evaluation in the abc reference frame based on the salinity concentrations of the salty and fresh water bodies entering the membrane modules and the phasor voltages at the terminals of the generation plant. The induction generator is selected as the power transductor. The assembled model also collects main phenomena affecting the PRO process efficiency: internal concentration polarization, external concentration polarization and spatial variations. A numerical example is presented where the model is used to evaluate the electric complex power output of the PRO generation plant. The numerical results obtained suggest that reactive power compensation may be needed for the selected power transductor. These results also confirm that the main phenomena affecting the PRO process efficiency substantially affect the active power production, but not the reactive power consumption. In this way, the assembled model may be used to analyse the steady state performance of electric networks under the integration of PRO generation plants.