Salinity gradient energy (SGE) arises from the releasing of Gibbs free energy when two solutions with different concentrations are mixed. Through the effective control of the mixing process, the SGE can be converted into practical work such as electrical power. Theoretically, the total available SGE from the river mouths worldwide is estimated at 625 TWh per year, which is 3% of the world electricity consumption.
There are several techniques of extraction the SGE into practical energy, my PhD research project focuses on the capacitive technique, by taking advantage of the change of properties of the electric double layer (EDL) formed at the porous electrode surface when seawater and fresh water intermittently flow through the cell. Based on the electrode materials, operational modes, and device configurations, the CapMix can be classified into several sub-groups. Our idea is to compare and evaluate all the CapMix techniques and select one suitable technique for further scale it up. In addition, we are also trying to develop the corresponding models to simulate the whole CapMix process. The developed models will be useful for future optimization the technique.
We have recently made a comprehensive evaluation of all the CapMix techniques and the results shown that using ion exchange membranes and additional charging into the device can significantly improve the system performance. However, all the existed CapMix techniques are operated on a discontinuous power output mode. And currently I am trying to develop a new device configuration, by replacing the solid electrodes with liquid electrodes to realize the continuous power generation and further improve the system performance.