The first osmotic plant in France will produce 4 TWh per year in 2023

Thanks to the technology of the French startup Sweetch Energy, which applies an electrode system to the selective membrane of natural nanofibers, the plant should be competitive.

The osmotic plant will generate ¼ of the electricity consumed by two cities like Seville and Zaragoza in 1 year.

Producing clean energy at the mouth of the Rhône. Thanks to the encounter between the fresh water of the river and the salt water of the Mediterranean.

That’s the brainchild of the Compagnie Nationale du Rhône, a company that manages hydroelectric power generation from 50 dams on the main river in southern France and other wind and photovoltaic farms.

With a Breton start-up, Sweetch Energy, it will inaugurate an osmotic plant in 2023.

How an osmotic power plant works.

Osmotic energy is also known as salt gradient energy or blue energy, and is generated by taking advantage of the salinity differential between river water and sea water.

The latter have a higher concentration of certain salts, mainly sodium and chlorine, in ionized form (Na+ and Cl-).

Over the years, various methods have been developed to harness this energy. The best known is pressure retarded osmosis, which, as its name suggests, uses water pressure directly to drive a hydro turbine.

The French plant, for its part, is based on a new process, patented by Sweetch Energy itself. This is called “INOD®” technology, which stands for “Nano Osmotic Ion Diffusion“. The solution exploits an effect discovered in 2013, whereby huge electrical currents are generated, osmotically induced, by nanoscale salinity gradients.

New prototype.

To date, there are few examples of osmosis installations in the world. The first became operational in Norway in 2009, but it was a very small prototype. Produced by state-owned Statkraft, the plant only produced 2-4 kWh, enough to run a coffee machine.

The challenge for the Breton start-up is to use the INOD® technology to allow the exploitation of the energy of the salt gradient on a large scale.

The potential of this clean energy source from osmosis is estimated at around 30,000 TWh worldwide, more than the entire annual electricity demand.

The bottleneck, so far, is the cost of the osmosis process versus the amount of electricity generated.

Sweetch Energy has developed a special membrane composed of nanofibers of natural materials, on which the electrodes adhere.

The system, guarantees start-up, achieves efficiency levels that finally make this technology competitive with other renewable sources: they are 20 times more efficient than traditional ones and cost 1/10 of the current price.

When fully operational in 2030, the plant at the mouth of the Rhône should produce 4 TWh of electricity per year, or around ¼ of the annual energy demand of two cities such as Zaragoza and Seville.

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