Real-Time Emulation of a Pressure-Retarded Osmotic Power Generation System

Power production by conversion of salt gradient energy (osmotic power production) has the potential for global commercialization. Research on the net-power output and osmotic power plant configurations could result in viable methods for improvement of plant efficiency. In this paper, a novel equivalent electric-circuit model of the pressure-retarded osmosis (PRO) process is described and is used to develop a power-hardware-in-the-loop (PHIL) emulator to represent the osmotic power plant. The model considers many dynamics involved with PRO including reverse salt leakage, concentration polarization, and the salt storage capacity of water. The proposed model facilitates real-time dynamic simulation and analysis of the PRO power plant, and its interaction with the rest of the PRO power system, namely the impulse turbine and the synchronous generator supplying power to off-grid or isolated loads. The response of the multidomain system including hydraulic, mechanical, and electrical components of the system is observed, given changes in the input parameters such as source flow rate. The proposed PHIL emulator provides insight into the operational dynamics and behavior of the PRO system. The proposed real-time emulator serves as a powerful tool that can advance research and development of PRO power generation systems. Simulation and experimental results are presented in this paper to validate the PRO plant model and the operation of the proposed real-time PHIL PRO emulator.