Japan’s Largest Grid-Connected Battery Storage to Be Built in Osaka

Osaka, Japan — Kansai Electric Power Co., Kinden Corporation, and Japan Excellent Infrastructure (JEXI) have announced plans to build one of Japan’s largest grid-connected battery storage facilities in Misaki Town, Osaka Prefecture. The Tannowa Battery Plant will feature an output capacity of 99 MW and a storage capacity of 396 MWh.

On May 7, the companies disclosed the formation of a new entity dedicated to the development of grid-scale energy storage projects. Established on March 7, the new company is backed by Kansai Electric with a 40% stake, Kinden with 10%, and the Japan Infrastructure No.1 Investment Limited Partnership (JI1) — a domestic infrastructure fund advised by JEXI — holding a 50% stake.

Construction of the project is scheduled to begin in June 2025, with commercial operations expected to commence in February 2028.

The battery plant will participate in three market segments: the wholesale electricity market, the capacity market, and the supply-demand balancing market. It will utilize lithium-ion battery systems manufactured by U.S.-based Tesla.

Kansai Electric will oversee business development, battery diagnostics, and operational support, while Kinden will manage engineering, procurement, and construction (EPC). Korea Electric Power Asset Management (KEPAM) will be responsible for asset operations and management. E-Flow, a subsidiary of Korea Electric Power Group, will handle battery storage system operations within the electricity market. Additionally,

Kinden Kansai Services will be in charge of maintenance operations.

JEXI will lead project structuring and financing support, with Mitsubishi UFJ Bank arranging the project financing. Notably, this project marks Japan’s first use of non-recourse project financing for an energy storage facility operating solely on revenues generated from electricity market transactions.

This announcement follows Kansai Electric’s recent progress in large-scale battery storage. In December 2024, Kansai Electric, in partnership with ORIX Corporation, completed and began operating the Kinokawa Energy Storage Plant in Kinokawa City, Wakayama Prefecture. With a capacity of 48 MW / 113 MWh, it currently stands as Japan’s largest operational grid-connected battery storage project.

As Japan accelerates its energy transition and strengthens grid resilience, these landmark projects highlight the increasing role of battery storage in supporting a sustainable, low-carbon energy future.