On February 21, 2025, Tohoku Electric Power returned Unit 2 of the 2.6MW hydroelectric Miyanohara Power Plant in Niigata Prefecture, Tsunan Town, into commercial operation. With that, it completed the nearly 100-year-old power plant’s repowering.
While the power plant’s output capacity was not increased during the process, the upgraded equipment is expected to lead to an approximately 8% increase in its generation. Tohoku EPCO also expects the power plant to be more reliable and its maintenance to be less labor intensive, resulting in less downtime.
Repowering work on the power plant commissioned in 1928 started in March 2022 with Unit 1, followed by Unit 2 in November 2023. Unit 1 was returned into commercial operation in March 2024.
Miyanohara Power Plant is one of over 200 hydro power plants totaling about 2.5GW owned by Tohoku EPCO. With over 40% of the power plants accounting for approximately 10% of the capacity, being nearly or over 100 years old, the company has been working on repowering the aging assets. Most recently before Miyanohara, at the end of January 2025, Tohoku EPCO finished the process for Horai Power Plant’s Unit 3.
Correction (March 2, 2025): The previous version of this story stated Tohoku EPCO had over 150 hydro power plants and incorrectly stated its hydro power plants total about 1.3GW, with approximately 20% of the capacity being nearly or over 100 years old.
