Japan's largest power producer Jera is considering wider use of storage batteries to help prolong the operation of its thermal power fleets.
This system would cut the risk of malfunctions by reducing the number of start-stop cycles required for the units given the growing use of intermittent renewable energy.
It remains unclear when, where and at what scale Jera will install battery storage systems. The company plans to assess the benefits of battery storage in 2026 by comparing them with the cost of repairing thermal plants, particularly gas-fired units, that break down because of frequent start-up and shutdown cycles, president Hisahide Okuda said on 18 February. Battery storage would have little value if it cannot reliably reduce cycling frequency, he added.
Installation of storage batteries is typically required to back up weather-dependent renewable output such as solar and wind. But the need has grown even more because thermal plants have been forced to start up and shut down more frequently than expected in recent years given rising renewable generation.
Jera recorded about 110 operational cycles at its coal-fired plants and roughly 12,500 cycles at its gas-fired units in the April 2024-March 2025 fiscal year, up by around 3½ times and 2½ times, respectively compared with 2014-15.
An unexpected shutdown of thermal plants would pose risks to stable electricity supply, especially given the limited nuclear output in the Tokyo area and the absence of nuclear generation in the Chubu region, where Jera operates. The Tokyo area has only one reactor — the 1,356MW Kashiwazaki-Kariwa No.6 unit — in operation, which began test runs on 16 February after a 14-year hiatus following the 2011 Fukushima nuclear disaster.
Thermal power plants would play a vital role in meeting the expected rises in electricity demand from data centres and in balancing fluctuations in renewable output. It is important to prevent thermal generators from breaking down and to ensure quick repairs when they do, for example by increasing inventories of critical materials, according to Okuda.
Securing LNG with sufficient volumes, flexible contract terms and even under emergency-response arrangements will also be essential for continuing to operate gas-fired plants. Jera signed an initial agreement with state-owned QatarEnergy and Japan's trade and industry ministry Meti on 3 February to establish a trilateral co-operation framework that would enable the supply of additional LNG cargoes during emergency situations. This coincided with a 27-year supply deal with QatarEnergy to buy up to 3mn t/yr from 2028. The company also secured a combined 5.5mn t/yr from US suppliers in 2025, under destination-free contracts.
