Thanks to the technology of the French startup Sweetch Energy, which applies an electrode system to the selective membrane of naturally occurring nanofibers, the plant is expected to be competitive.
The osmotic power plant will generate ¼ of the electricity consumed by two cities such as Seville and Zaragoza in 1 year.
Produce 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.
This is the idea behind the Compagnie Nationale du Rhône, a company that manages the generation of hydroelectric power in 50 dams on the main waterway in the south of France and other wind farms and photovoltaic plants.
Together with a Breton startup, Sweetch Energy, it will inaugurate an osmotic power 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 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 the name explains, uses water pressure directly to drive a hydroturbine.
The French plant, on the other hand, is based on a new process, patented by Sweetch Energy itself. It’s called “INOD®” technology, which stands for “Ionic Nano Osmotic Diffusion«. The solution takes advantage of an effect discovered in 2013, whereby huge electrical currents are generated, osmotically induced, by nanoscale salinity gradients.
To date, there are few examples of osmosis plants in the world. The first became operational in Norway in 2009, but it was a very small prototype. Produced by the state-owned company Statkraft, the plant produced just 2-4 kWh, enough to run a coffee machine.
The challenge for the Breton startup is to use 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 to be around 30,000 TWh worldwide, more than the entire annual demand for electricity.
The bottleneck, until now, is the cost of the osmosis process in relation to the amount of electricity generated.
Sweetch Energy has developed a special membrane made of nanofibers of natural materials, to which the electrodes adhere.
The system, guarantees the start-up, allows to reach levels of efficiency that make this technology finally competitive with other renewable sources: they are 20 times more efficient than traditional ones and cost 1/10 of the current price.
When it is fully operational, in 2030, the plant at the mouth of the Rhône should generate 4 TWh of electricity per year, that is, approximately ¼ of the annual energy demand of two cities such as Zaragoza and Seville.
More information: www.sweetch.energy