In the city of Fukuoka, on Japan’s southern coast, something very new and exciting just began. Japan has officially launched Asia’s first osmotic power plant, a renewable energy facility that creates electricity simply by mixing fresh water and seawater. It might sound surprising, but this small step could become a big part of how Japan and the rest of the world fight climate change. So, let’s find out more about it.
So, what exactly is osmotic power?
It’s based on osmosis, a natural process that happens all around us — it’s how plants absorb water from the soil and how our own cells stay hydrated. In simple terms, osmosis is the movement of water from a place with less salt (fresh water) to a place with more salt (seawater) through a thin barrier called a membrane. Here’s how it works step by step:
On one side of the membrane, there’s fresh water or treated wastewater.
On the other side, there’s seawater that’s made even saltier using leftover brine from a desalination process.
The difference in salt levels makes the fresh water push through the membrane, increasing pressure on the salty side.
That pressure spins a turbine, which generates electricity.
Professor Sandra Kentish, a chemical engineer at the University of Melbourne, explained to The Guardian that Japan’s plant is special because it uses concentrated seawater — the leftover brine from desalination. This makes the salt difference bigger, so more energy can be produced.
Not many osmotic power plants in the world
This is the second osmotic power plant in the world, following another in Denmark that opened in 2023. But Japan’s version is larger, more advanced, and shows real progress for this new form of renewable energy.
Kenji Hirokawa, director of the Seawater Desalination Center, which runs the plant, said: “It’s a meaningful project — maybe the start of something bigger — in our response to climate change.”
How Japan’s osmotic power plant works
The Fukuoka plant is able to produce about 880,000 kilowatt-hours of electricity every year. That’s enough to power around 220 homes and also help run a nearby desalination facility, which turns seawater into drinkable water.
For comparison, that’s about as much electricity as two soccer fields full of solar panels could produce — but the key difference is that osmotic power runs day and night, in any weather, all year long.
Clean, renewable, and always running
This process is 100% renewable and produces no carbon emissions. Because rivers and oceans are everywhere and never stop flowing, Japan’s osmotic power plant can generate electricity all day, every day, unlike solar or wind energy that depends on the weather.
As Kenji Hirokawa told NHK: “It’s a stable source of energy that can operate 24 hours a day, every day of the year.”
Why it took so long to build osmotic power plants
Although the idea of osmotic power sounds simple, it has been very hard to make it work efficiently on a large scale. Professor Kentish explained:
“While energy is released when salt water mixes with fresh water, a lot of energy is lost when pumping the water into the plant and because of friction across the membranes. So, the total energy that can be produced is small.”
The first prototype plant was built in Norway in 2009 by the company Statkraft. It proved that osmotic energy worked — but the technology was too expensive and inefficient to expand.
But…
The main challenges are:
Energy loss when pumping water through the system.
Friction that slows down the process inside the membranes.
High costs of building and maintaining the plant.
Even so, scientists have never given up. Apart from Japan and Denmark, there are small projects in Norway, South Korea, Spain, Qatar, and Australia. In Australia, the University of Technology Sydney (UTS) paused its osmotic project during the pandemic, but researcher Dr. Ali Altaee hopes to restart it soon: “We have salt lakes near Sydney that could be used, and we also have the knowledge to make it happen,” he said.
A hopeful step for Japan and the world
At the launch ceremony in Fukuoka, Professor Akihiko Tanioka, a pioneer of osmotic technology in Japan, was visibly emotional. “I feel overwhelmed that we were finally able to make this real. I hope it spreads not only in Japan but across the world,” he told Kyodo News.
For now, osmotic power only provides a tiny fraction of the world’s electricity. But researchers believe that if efficiency improves, it could eventually supply up to 15% of global energy demand by 2050 — making it one of the largest unused renewable sources on Earth.
AloJapan.com