The osmotic power plant will generate ¼ electricity consumed by Milan in 1 year
(Sustainabilityenvironment.com) – Produce clean and perennial energy at the mouth of the Rhône. Thanks to the encounter between the freshwater of the river and the saltwater of the Mediterranean. This is the idea of the Compagnie Nationale du Rhône, a company that manages the generation of hydroelectric power from about 50 dams on the main waterway of southern France and other wind and photovoltaic parks. Together with a Breton startup, Sweetch Energy, in 2023 will inaugurate an osmotic energy plant.
How does an osmotic power plant work?
Osmotic energy is also known as saline gradient energy and is generated by exploiting the salinity differential between the river and marine waters. The latter has a higher concentration of some salts, especially sodium and chlorine, in the ionized form (Na+ and Cl-). Over the years, various methods have been developed to take advantage of this energy. The most known is the delayed pressure osmosis that, as the name explains, directly exploits the water pressure to operate a hydro turbine. The French power plant relies instead on a new process, patented by Sweetch Energy itself. Let’s talk about the “INOD®” technology, acronym of “Ionic Nano Osmotic Diffusion“. The solution exploits an effect discovered in 2013, so immense electric currents, induced osmotically, are generated by salinity gradients on the nanoscale.
The prototype at the mouth of the Rhône
To date there are few examples of osmosis power plants in the world. The first came into operation in Norway in 2009, but it was a very small prototype. Produced by the state-owned company Statkraft, the plant produced only 2-4 kWh, enough for operations such as starting a coffee machine.
The bet of the Breton startup is to use the technology INOD® able to allow the exploitation of the energy to the saline gradient on a large scale. In the world, it is estimated that the potential of this clean energy source by osmosis, considered all river mouths, is about 30,000 TWh: more than the entire annual global demand for electricity.
The bottleneck, so far, is the cost of the osmotic process about the amount of electricity generated. Sweetch Energy has developed a special membrane, composed of nanofibers of natural materials, to which electrodes are associated. The system, guarantees the startup, allows to reach levels of efficiency that make this technology finally competitive with other renewable sources: they are 20 times more performing than traditional and cost 1/10 of the current price.
At full power, in 2030, the plant at the mouth of the Rhône should generate 4 TWh of electricity per year, which is about ¼ of the annual energy demand of a city like Milan.