At a time when discussions are multiplying on energy independence and the development of renewable energies, the Compagnie Nationale du Rhône is launching into osmotic energy. The Compagnie Nationale du Rhône is the France’s leading producer of exclusively renewable energy, and the Rhône concessionaire for hydroelectricity production, river transport and agricultural uses.
A pilot project will be launched in the Rhône delta thanks to the technological support of Sweetch Energy, a startup created in 2015 in Rennes. The industrial partnership has just been signed, the test phases will begin at the beginning of the year in the laboratories of the CNR (Compagnie Nationale du Rhône) in Lyon, and the plant should be operational at the end of 2023.
The plant will be built with biomaterials for 100% renewable energy production. Tests are currently being carried out in different areas of the delta to determine the exact location of the implantation.
Osmotic energy uses the reaction resulting from the meeting between fresh water and salt water. “The principle consists of bringing a flow of fresh water and a flow of salt water into an osmotic generator made up of several membranes installed in large cabinets”, explains Nicolas Heuzé. The two flows circulate gently along these membranes whose specific properties allow the ions to generate electricity.
Osmotic energy is released naturally as soon as fresh water from rivers meets salt water from the sea and ocean, so the plant will use part of the flow from the Rhône and part of the water from the Mediterranean to create current.
“It’s 100% carbon-free energy.”
Nicolas Heuzé, founder of Sweetch Energyat franceinfo
The advantage of this system is that the energy production is permanent and independent of weather conditions.
The objective of this pilot project is to demonstrate that osmotic energy can eventually become a basic and complementary energy for other types of production, in particular hydraulic energy. Nicolas Heuzé estimates that on the Rhône, this osmotic power plant will produce more than 4 million megawatt-hours each year. (MWh), i.e. twice the annual electricity consumption of the inhabitants of Marseille. For comparison, a 900 MW nuclear reactor produces about 5.5 million MW per year.
“Osmotic energy has been studied for more than 70 years”, emphasizes Nicolas Heuzé. Several plants have been developed in northern Europe, notably in Norway and the Netherlands, but the technologies used were older and less efficient. Sweetch Energy has developed a more efficient technology thanks to the support of the CNRS and the institute Pierre-Gilles de Gennes in Paris. It succeeded in multiplying the performance of membranes by 20 and dividing the cost of materials by 10.
With global warming and increasing periods of drought, the level of rivers is set to drop.
“For the Rhône, it is estimated that the flow of the river will drop by 10% by the end of the century”, explains the entrepreneur. Osmotic energy is therefore a means of overcoming the production difficulties of hydroelectric power stations. “It’s a very good complement”, insists Nicolas Heuzé who specifies that many works are currently being carried out in the United States and in Asia, because by 2050, this source of renewable energy could represent nearly 15% of the planet’s electricity needs.
According to the co-founder of Sweetch Energy, 30,000 TWh* (Terawatt-hour) of osmotic energy is dissipated each year in deltas and estuaries, a capacity greater than the annual world demand for electricity.
* The terawatt-hour is a unit of measurement of energy. 1 TWh equals 1 billion kwH (kilowatt-hour)