ENEOS 431 MW Negishi Plant Closure Highlights Challenge of Replacing Thermal Plants

According to Bloomberg, ENEOS Holdings will permanently close its 431 MW oil-fired integrated gasification combined-cycle plant at the Negishi refinery in Yokohama on September 1, citing JEPX data published a year ago. An ENEOS spokesperson confirmed the closure and attributed it to profitability concerns without providing further details.

The loss of 431 MW of capacity will further tighten Tokyo’s supply balance by removing dispatchable capacity as demand rises, partly due to data center expansion. The restart of Kashiwazaki-Kariwa Unit 6and continued renewable expansion may also have reduced Negishi’s expected utilization and added pressure for the closure, although ENEOS has not confirmed this.

While the Negishi plant’s closure was planned last year, its retirement now comes against an increasingly challenging supply-demand environment in Tokyo. TEPCO Power Grid’s first renewable curtailment order in March highlighted the increasing challenge of controlling the supply/demand balance in Tokyo. As a synchronous thermal generator, the Negishi plant also provides inertia that stabilizes grid frequency during disturbances. Its closure means these services must come from other sources.

🔍 Shulman Commentary:

The closure reflects the gradual shift in Tokyo’s generation mix, as high fuel and maintenance costs and decarbonization policies continue to reduce the competitiveness of oil-fired generation. While the loss of 431 MW is relatively modest in the context of the overall Tokyo system, it removes a source of dispatchable and synchronous capacity at a time of rising demand and increasing renewable penetration. This broader transition will gradually create additional opportunities for other generation sources and flexible resources, including BESS, as Tokyo’s power system adapts to rising demand and greater renewable deployment.

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