Penn State University researchers have succeeded in creating a new type of hybrid technology, which can generate “unprecedented” levels of electricity by utilizing the change in salt concentrations where oceans are joined by freshwater rivers.

Technologies to generate electricity from estuaries isn’t new, but the new technology is much more efficient than the old technology. Previously there were two different ways of harvesting energy from areas where rivers meet oceans, pressure retarded osmosis (PRO) and reverse electrodialysis (RED). However, both methods have thus far failed to meet the requirements to be viable as methods of energy generation.

The Penn State researchers engineered a solution by combining RED technology with capacitive mixing, or CapMix, in an electrochemical flow cell. Christopher Gorski, assistant professor of environmental engineering at Penn State, said that combining the two processes resulted in the generation of “a lot more energy”. The hybrid device uses a combination of chloride transferring and switching the flow path of freshwater and saltwater to generate energy.

“There are two things going on here that make it work,” Gorski said. “The first is you have the salt going to the electrodes. The second is you have the chloride transferring across the membrane. Since both of these processes generate a voltage, you end up developing a combined voltage at the electrodes and across the membrane.”

Currently, the Penn State researchers are pleased with the results of their work but are aiming to improve on the technology. More research on the stability of the electrodes over time must be done, as well as investigations into if other elements like sulfate or magnesium in the seawater might degrade cell performance.

“Pursuing renewable energy sources is important,” opines Gorski. “If we can do carbon neutral energy, we should.”