When salt water and fresh water are separated by a semipermeable membrane, fresh water molecules move into the salt water to dilute it. This phenomenon, known to scientists since the 1950s, is called osmosis.
This is what happens when you put salt on a cucumber to squeeze out the water. This movement of molecules generates a pressure called osmotic energy.
The latter is released in large quantities in places where fresh water and salt water meet: deltas, estuaries, etc.
Since the 2000s, pilot plants for osmotic power have been implemented in Norway and the Netherlands, using seawater and river water to generate electricity. An expensive device whose performance was not satisfactory, according to Lydéric Bocquet, a physicist at the Ecole Normale Supérieure specialising in nanometric-scale fluid mechanics. But recent scientific advances have enabled the development of new membranes with nanometric pores, which have considerably increased the efficiency of this technology.
“ It is estimated that, at the electrical level, approximately 15% of the world’s electrical power and energy could be provided by osmotic energy. explains Lydéric Bocquet.
In this video, produced in collaboration with Energy Night 2024, organised by the Escuela Normal Superior, we explain how osmotic energy works and what technologies allow it to be recovered.
“Understand in three minutes”
The explanatory videos that make up the series “Understanding in three minutes” are produced by the Vertical Videos department of World. Distributed mainly on platforms such as TikTok, Snapchat, Instagram and Facebook, their aim is to contextualise major events in a short format and make news accessible to everyone.
