'Electricity Generation with Only Water'... Korean Researchers Greatly Improve Salinity Gradient Power Technology

Korea Institute of Energy Research, Dr. Nam Ju-yeon Marine Convergence Research Team

[Asia Economy Reporter Kim Bong-su] A Korean research team has developed a technology that significantly improves the performance of "reverse electrodialysis salinity gradient power generation," which produces electricity by utilizing the salinity difference between brine and freshwater.

The Korea Institute of Energy Research announced on the 29th that Dr. Nam Ju-yeon and her marine convergence research team developed a technology that dramatically enhances the performance of reverse electrodialysis salinity gradient power generation, which produces electricity from the salinity difference between brine and freshwater.

Salinity gradient power generation is an eco-friendly and safe energy source with a global potential capacity of 2.6 TW (terawatts). It also holds immense potential as an energy production technology that can most effectively solve the low utilization rate and load fluctuation problems of existing renewable energy sources. This power generation converts the ion concentration difference in solutions into electrical energy. While it has the great advantage of producing electricity without carbon emissions as long as water is available, there are still challenges to be resolved before commercialization. Representative issues include energy loss and cost increases due to concentration polarization phenomena and pretreatment problems of the inflow water.

Additionally, existing reverse electrodialysis stacks mainly use a parallel flow method where brine and freshwater flow simultaneously between stacked ion exchange membranes. This method requires increasing the water inflow speed to minimize concentration polarization, which in turn demands high pumping and pretreatment energy and results in larger sizes, making the design of compact plants difficult.

The research team developed a new cascade-type reverse electrodialysis stack. This stack divides a single stack into multiple stages, recirculating the water used in the previous stage to the next stage, thereby increasing the utilization rate of the inflow water. As a result, the concentration polarization phenomenon was significantly reduced while maintaining high energy efficiency.

In the case of the cascade stack, the net power improved by 20% compared to conventional stacks. Furthermore, the longer travel distance (residence time) of the inflow water inside the stack blocked the path of leakage current, resulting in the generation of more current. Using a 4-stage stack, the volume of inflow water required for maximum power production can be reduced to one-fourth. Compared to existing stacks, energy density improved by up to 480%, and efficiency increased by up to 420%.

The research results were published online in July in the international water resources journal Water Research.

This content was produced with the assistance of AI translation services.