Kyushu Electric Power launched the environmental impact assessment process for a 100MW-class pumped storage project that would use the existing Shimouke and Matsubara dams on the border of Oita and Kumamoto prefectures.
According to a primary consideration submitted to METI on August 27, 2026, construction is expected to begin in 2030, with commercial operation following in 2038. The conventional 15MW Shimouke and 50.6MW Matsubara hydropower plants, which use the two dams and were commissioned in 1969 and 1971, respectively, will continue to operate.
The utility might participate in one of the upcoming long-term decarbonization auctions to secure a capacity contract for the project. OCCTO data shows that to date, seven replacement and new pumped storage units were awarded under the scheme, including Hokkaido Electric Power’s 200MW Kyogoku Unit 3. In the FY2026 round, METI proposed increasing the bid cap for new pumped storage assets by 72% to 200,000 yen per kW-year.
Shimouke-Matsubara is poised to be Kyushu Electric Power’s first new pumped storage power plant since the 1.2GW Omarugawa in Miyazaki Prefecture was commissioned in phases between July 2007 and July 2011. The utility also operates the 500MW Ohira in Kumamoto Prefecture and the 600MW Tenzan in Saga Prefecture. Separately, it is considering retrofitting the conventional 50MW Morozuka Power Station with pumps by FY2033.
