서강대학교

초록/요약

Renewable energy is released when feed water with different salinity mixed. This energy can be captured currently by three methods to convert into electricity: pressure retarded osmosis (PRO), reverse electro-dialysis (RED) and capacitive mixing (CAPMIX). Among these technologies, RED has widely gained significant attention for decarbonization of the global energy system, climate changes and the growth in universal demand for basic energy access. Reverse electro-dialysis captures salinity gradient energy using a series of anion exchange membranes (AEM) and cation exchange membrane (CEM). Anions pass through the AEM towards the anode and cations move through the CEM towards the cathode. At the electrodes, the chemical energy converts to electric energy by redox couple reaction without moving parts and low fouling issues. This thesis investigates the optimization of the reverse electro-dialysis, with a strong focus on Nafion based sulfonated single-wall carbon nanotube (s-SWCNT) as a cation exchange membrane, ion transport, hydrodynamic loss, concentration polarization, applied current and spacer effects on the RED process performance. Here we have demonstrated novel nanocomposite membrane in reverse electro-dialysis system for power generation. The performance of the Nafion based nanocomposite and pure Nafion with the FAA-3 based anion exchange membrane expressed in terms of open-circuit voltage (OCV), maximum power density, and net power density. The maximum power density boosted with the higher feed solution flow rate. On the other hand, the net power density decreases as the feed solution flow rate increased. The output performance of the RED stack compares with two different spacers having a thickness of 300 µm and 500 µm. The OCV, maximum current between the 300 µm and 500 µm was little change. The net power density, on the other hand, significantly improved. It is noted that spacer with a thickness of 300 µm shows an 80% loss in net power density when the flow rate of feed solution increases from 25 to 75 mLmin-1. However, the trend of plot inversed in a 500 µm thick spacer thus net power density shows very little change as the flow rate increase. Nafion nanocomposite with FAA-3 membranes implanted in RED stack obtained a very high maximum power density ~ 79.4 mW m2 at 75 mLmin-1.