Haley Zaremba
Haley Zaremba is a writer and journalist based in Mexico City. She has extensive experience writing and editing environmental features, travel pieces, local news in the…
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By Haley Zaremba – Sep 20, 2025, 4:00 PM CDT
- Japan inaugurated its first commercial osmotic power plant in Fukuoka, producing 880,000 kWh annually by leveraging desalination brine.
- Osmotic energy, recently named a top emerging technology by the World Economic Forum, offers constant, carbon-free baseload power.
- With the potential to meet nearly 20% of global electricity demand, osmotic energy is gaining traction despite efficiency challenges.
Japan just became the second country in the world to launch a commercial-scale osmotic energy plant, a big win for the little-known form of clean energy generation that first broke ground in Denmark. While osmotic energy is nascent and its testing grounds remain limited, it has big potential – The World Economic Forum recently named osmotic power systems as one of the top 10 emerging technologies to watch in 2025.
This form of carbon-free energy generation uses osmosis between freshwater and saltwater to create power. In other words, it works by moving water from a less concentrated solution to a more concentrated one across a semipermeable membrane. “When freshwater and seawater meet, a natural gradient in salinity is created, prompting ions to migrate from the saltier side to the less salty side in pursuit of equilibrium,” an Earth.org article explains in layman’s terms. “The movement of water and ions generates a pressure differential that can be harnessed to produce electricity.”
The result is a baseload form of totally clean and carbon-free energy production that is available 24 hours a day, seven days a week, 365 days a year. This is critical for energy security, as the majority of clean energy capacity, namely wind and solar, is variable. This means that osmotic energy could be an excellent alternative clean power from an energy security perspective.
Denmark brought the world’s first commercial-scale osmotic power plant online in 2023. This month, Japan followed suit with a brand new plant in Fukuoka. The plant began operations on August 5, and will produce 880,000 kilowatt-hours a year. The plant was developed in tandem with a local desalination plant. The use of extra-salinated water leftover from the desalination process lends itself perfectly to the osmosis model by increasing efficiency while also reducing waste. “Those stronger gradients boost efficiency and grounds osmotic generation in existing systems rather than the lab,” reports New Atlas.
“I feel overwhelmed that we have been able to put this into practical use. I hope it spreads not just in Japan, but across the world,” Akihiko Tanioka, professor emeritus at the Institute of Science Tokyo, told Kyodo News.
Pilot-scale osmotic energy models have already been developed in other nations around the world including Norway,