Estuaries and their surrounding wetlands are bodies of water usually found where rivers meet the sea. Estuaries are ecosystems constantly in flux where fresh and ocean water meet and mix. These estuaries also serve some natural filters for runoff and providing nursery grounds for many species of birds, fish, and other animals.
By taking advantage of it, researchers at Penn State developed a new hybrid technology. This hybrid technology combines the most effective pieces of existing methods for capturing energy created by differences in salt concentrations in water. It produces unprecedented amounts of electrical power in places where saltwater and freshwater meet.
Until now, pressure retarded osmosis (PRO) is commonly used method for seizing the energy from salt concentration. It allows water through a semi-permeable membrane and blocks salt back. Thus, it creates osmotic pressure that moves turbines, generating power.
Although, the membranes in PRO gets compressed and becomes less useful with extremely salty water. This issue is then sorted out by reverse electrodialysis (RED) method, but it generates only small amounts of power. The method transmits salt through its membranes instead of water.
To sort this issues out, scientists created an electrochemical flow cell that features both the RED and Capacitive mixing (CapMix) technologies. CapMix is the technique that draws energy from the voltage when two electrodes are immersed in water whose salt concentration changes. Mixing CapMix with the RED technology increased energy production efficiency by more than four times compared to RED alone.
Scientists said, “Harnessing the difference in salt concentration with their technique has the potential to create energy sufficient to meet as much as 40 percent of the world’s energy needs. This technology could go a long way toward eliminating most of the country’s reliance on fossil fuels.”
“This technology is so efficient that countries would simply need to head to the coast to get the technology in place — assuming they could afford it.”
Scientists noted, “the results are promising, the work isn’t done yet. We need to find out how stable the electrodes remain over time and how other seawater elements such as sulfate and magnesium could affect the cell’s performance. Hopefully, we’ll see positive results from more long-term testing soon so this carbon-neutral energy source can be harnessed. As the U.S. moves toward further deregulating the fossil fuel industry, the timing could be crucial.”