Japan’s First Osmotic Power Plant Starts Operating in Fukuoka

Japan’s first osmotic power plant, which generates electricity from the difference in salt concentration between seawater and freshwater, began operations in early August in a southwestern prefecture, Kyodo News reported.

The Fukuoka plant, which began operations on Aug. 5, is expected to generate 880,000 kilowatt-hours (kWh) annually. (Photo: Kyodo News)

The Fukuoka District Waterworks Agency, the world’s second operator to use the technology after a Danish firm in 2023, described it as “a next-generation renewable energy source that is not affected by weather or time of day and emits no carbon dioxide.”

In the process—also called salinity gradient power—electricity is produced when concentrated seawater, created by extracting freshwater, is separated by a permeable membrane from treated water from a sewage facility.

The membrane blocks impurities other than water.

A turbine is rotated by the pressure created as water flows from the freshwater to the saltwater reservoir, with a generator producing electricity from the turbine’s motion.

The Fukuoka plant, which began operations on Aug. 5, is expected to generate 880,000 kilowatt-hours (kWh) annually. The electricity will power a desalination facility that supplies fresh water to the city and neighboring areas.