Japan’s Electric Power Development Company (EPD) has completed 15 months of a five-year test of the world’s first seawater pumped storage plant. Several new technologies are being tested at the 30MW Okinawa Yanburu pumped storage plant. These include a rubber sheet lining for the 564,000m3 reservoir, 136m long fibre reinforced plastic penstocks to deliver impounded sea water to the turbines, and austenite stainless steel for the turbine and pump blades.

In addition to measuring salt water lechate from the reservoir; pump and turbine corrosion; and the growth of algae and marine life forms within the system, the project is also assessing the impact of wind-driven saline spray on the land surrounding the reservoir. The idea to develop seawater pumped storage was first approached in 1987 and construction of the plant began in 1999. Demonstration tests began on 16 March 1999 and will continue until 2004.