Osmotic power breakthrough could be the next major renewable energy

14 Jul 2016

Offering unprecedented yields of clean energy, researchers have developed a new method of harvesting electricity using fresh and salt water, referred to as osmotic power.

As a concept, osmotic power is simple, in that fresh water is put in contact with salt water through an ultra-slim membrane.

When this occurs, the salt ions in the salt water travel through the membrane until the concentrations of salt in both liquids reach equilibrium, entering the state of osmosis.

These salt ions, which contain an electrical charge, can then be harvested to create usable electricity for the wider grid.

Developed by researchers from École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, this particular osmotic power generation system has reportedly generated ‘never-before-seen yields’ thanks to their specialised membrane, which measures just three atoms in thickness.

The EPFL research team has now published its findings in Nature, which revealed that the mighty energy yield is the result of the material used in the membrane, known as molybdenum disulphide.

High yield

This nanoporous material allows the positively-charged ions to pass through, while pushing away most of the negatively-charged ones and, according to the researchers, is the first time a 2D material has been used for osmotic power generation.

“We had to first fabricate and then investigate the optimal size of the nanopore,” said Jiandong Feng, lead author of the research.

“If it’s too big, negative ions can pass through and the resulting voltage would be too low. If it’s too small, not enough ions can pass through and the current would be too weak.”

To get an understanding of what potential osmotic power using this system could achieve, the team’s calculations found that, in an area of 1 sqm of the new membrane with 30pc of its surface covered in nanopores, it could produce 1MW of electricity.


A molybdenum three atoms thick selective membrane. Image via Steven Duensing /National Center for Supercomputing Applications, University of Illinois, Urbana-Champaign

Can generate power day and night

This, the team has said, would provide enough energy to power 50,000 energy-saving lightbulbs and, perhaps more importantly, the molybdenum disulphide used in the membrane is easily found in nature.

The only challenge now is scaling-up this process to become a feasible means of generating enormous amounts of electricity, while figuring out how to make relatively uniform pores in the membrane on such a scale.

If osmotic power becomes feasible, it offers huge potential for future clean energy generation as, while wind and solar energy are very dependent on the current weather or time of day, osmotic power is only limited by the availability of water.

Wave image via GraceOda/Flickr

Colm Gorey was a senior journalist with Silicon Republic