Clearer Waters Ahead for Blue Energy

by Justin Wenig

A captivating article published by an international team of scientists in the August issue of Nature magazine could make blue energy a powerhouse sustainable energy source in the near future. Blue energy, or osmotic power generation, refers to energy derived from the difference in salt concentration between freshwater and saltwater. At river estuaries, where river water and sea water meet, blue energy can be captured when molecules from the saltwater side move toward the freshwater side and spin a turbine.

Unfortunately, scientists have long struggled to develop a commercially viable generator with a positive return on investment. Case in point, the world’s first commercial osmotic power generator, commissioned by a Norwegian company Statkraft, could only produce enough energy to power one-tenth of one electric car battery before it was shunned in 2014. The cost? Ten years and over $100 million lost at sea.  

According to Jurica Dujmovic, a columnist at, the recent findings by EPFL (Ecole polytechnique fédérale de Lausanne) researchers could significantly improve the efficiency of commercial generators, and demonstrated it by building a small prototype generator. By crafting a thin membrane (similar to the intersection between saltwater and freshwater) with a selective nano-pore separating the two liquids, the researchers were able to increase the current flow of water, speeding up the turbine and capturing about a thousand times more electricity per square foot than the failed $100 million Statkraft generator.

What this means is, if scientists can scale the micro-generator pioneered by EPFL researchers, blue energy could vault toward the front of affordable sustainable energy sources. More, it could become an important tool in the growing arsenal of sustainable energy sources and a hedge against vicissitudes in weather that affect solar and wind energy.

It is worth noting that the potential impact of blue energy is contingent on the preservation of estuaries. For estuary conservation activists, the research findings serve as a strong argument against human-made estuary degradation and drainage. To wit, plentiful freshwater basins are needed to produce plentiful blue energy.  To some extent, this shifts the conversation on estuary conservation from an ethical one to an economic one.


Click to access nature18593.pdf


R.E. Pattle (2 October 1954). “Production of electric power by mixing fresh and salt water in the hydroelectric pile”. Nature. 174 (4431): 660. doi:10.1038/174660a0.



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