Extraction of Salinity Gradient Energy using a Hybrid Capacitive-mixing System.

Research paper by Jiho J Lee, Hongsik H Yoon, Jaehan J Lee, Taeyoung T Kim, Jeyong J Yoon

Indexed on: 25 Jan '17Published on: 25 Jan '17Published in: ChemSusChem


Salinity gradient energy (SGE) is a renewable energy source available wherever two solutions with different salinity mixes. Capacitive-mixing (Capmix) is a technology that directly extracts the salinity gradient potential through the movements of ions in high and low concentration solutions. However, the energy harvesting performance of Capmix needs further improvement. Herein, we propose a "hybrid Capmix", which consists of battery and capacitive electrodes. In this system, sodium ions and anions were captured/released to the metal oxide and carbon electrodes, respectively. The hybrid Capmix extracted an energy density that was approximately 3 times higher (130 J m-2) and exhibited a notable power output (97 mW m-2) compared to the previous Capmix using ion exchange membranes. Furthermore, the hybrid system operated successfully with real river and sea water. These results suggest that the hybrid Capmix could be a viable option to harvest energy from salinity gradients.