Electricity producer JERA has officially launched the environmental impact assessment process for a 2.6GW replacement project at its thermal power site in Sodegaura, Chiba Prefecture. The plan is to build three 870MW combined-cycle gas turbines and gradually retire four steam units that have been in service since the 1970s.
In a primary consideration document submitted to Japan’s Ministry of Economy, Trade and Industry (METI) and local authorities, JERA outlined a phased schedule. Construction of the first two units is expected to begin in fiscal years 2029 and 2030, with commissioning scheduled for 2032 and 2033. The third unit is slated for groundbreaking in fiscal year 2038 and a commercial start in 2041.
Gradual modernisation of a strategic site
The Sodegaura Thermal Power Station, with a current capacity of 3.6GW, began operations in 1974. The 600MW Unit 1 has been offline since March 2023. Units 4, 3 and 2 — each with a capacity of 1GW — will be gradually decommissioned between 2027 and 2032. The project marks a major technological shift, replacing ageing steam turbines with modern gas-fired generation.
The initiative was first announced in June 2025, aiming to ensure grid stability in the Kanto industrial region while adapting existing infrastructure to a changing energy mix. The new plant will rely on combined-cycle technologies designed to improve efficiency and reduce thermal losses.
Prospects for fuel flexibility
JERA has also signalled potential conversion of the future facilities to run on alternative fuels such as hydrogen or ammonia. Integration of a carbon capture and storage (CCS) system is also under consideration for later phases, although no definitive timeline has been released for these components.
The company, a joint venture between Tokyo Electric Power Company (TEPCO) and Chubu Electric Power, remains Japan’s largest power producer, with domestic thermal capacity of nearly 55GW as of the end of fiscal year 2023. In parallel, it is developing a 1.3GW repowering project at its Chita thermal power station with Toho Gas, and recently confirmed the decommissioning of 3.3GW of long-idled LNG and oil-fired capacity.
