Newsletter N°80 - September 2025 

⚡Energy: New Renewable Energy Source: Osmotic Power Arrives in Japan

A breakthrough in renewable energy: harnessing salt and fresh water to generate power around the clock

Japan has inaugurated its first osmotic power plant in the southwestern city of Fukuoka, marking only the second facility of its kind worldwide.
The plant is expected to generate about 880,000 kilowatt hours of electricity annually—enough to help run a desalination facility that supplies fresh water to Fukuoka and neighboring regions. That is roughly the equivalent of powering 220 Japanese households, according to the University of Technology Sydney.
Unlike solar or wind energy, osmotic power has the advantage of operating continuously, regardless of weather conditions, as it simply relies on the mixing of freshwater and seawater.

How does osmotic power work?
Osmosis is the natural process where water flows across a semipermeable membrane from a lower concentration to a higher concentration, attempting to equalize both sides.
In practice, osmotic power plants place freshwater and seawater on opposite sides of a special membrane. As water flows into the saltier side, the increased pressure drives a turbine connected to a generator, producing electricity.
At the Fukuoka facility, both treated wastewater and seawater are used. As the seawater becomes diluted and pressurized, part of it is directed through a turbine to create power.
 

Global progress and future challenges:
The Fukuoka plant builds on a growing global effort to harness osmotic energy. The world’s first facility opened in 2023 in Mariager, Denmark, developed by SaltPower. Similar pilot projects have been tested in Norway and South Korea, while prototypes have also been built in Spain, Qatar, and Australia.
Yet scaling up the technology is not without obstacles. A significant amount of energy is lost in pumping water and overcoming friction across membranes, which limits the net output. However, advances in membrane and pump design are gradually reducing these inefficiencies, raising hopes for more viable large-scale operations.

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Experts see Japan’s new plant as an important milestone, proving that osmotic power can contribute to future renewable energy portfolios. With abundant saltwater and freshwater resources in many regions of the world—including Australia’s salt lakes—researchers believe the technology could eventually be scaled to support more communities.