J-POWER announced it has completed the refurbishment of Unit 3 at the Okutadami hydropower plant, increasing the facility’s total capacity from 560MW to 566MW. This enhancement was made possible by replacing the unit’s turbine runner, boosting its output from 120MW to 126MW without altering existing water flow conditions.
Modernisation of a strategic facility
The Okutadami plant, located in Hinoemata Village in Fukushima Prefecture, now comprises four operational units. The first three, each initially rated at 120MW, have been operational since December 1960. A fourth unit with a 200MW capacity was added in June 2003, reinforcing the plant’s strategic role in national power supply.
The upgrade of Unit 3 is part of a broader series of interventions by J-POWER, officially known as Electric Power Development Co., Ltd. The company recently carried out similar refurbishments at its Nagayama, Suesawa, and Okamigo plants, aiming to enhance efficiency and increase output across its hydropower portfolio.
An expanding hydropower portfolio
J-POWER currently operates 61 hydropower plants with a total capacity exceeding 8.5GW, including seven pumped storage facilities that together generate around 5GW. This installed capacity positions the company as a key player in Japan’s hydropower sector. Its portfolio also includes the country’s second- and third-largest conventional hydro plants, the 400MW Tagokura plant in Fukushima Prefecture and the 350MW Sakuma plant in Shizuoka Prefecture.
According to the company, the modernisation of its assets is a major lever to strengthen grid reliability without the need for new dams. As no changes to hydrological conditions are required, this strategy reflects a focus on technical and industrial optimisation.
