Denki no Eki, a joint venture between JR Kyushu and Sumitomo Corporation units BS Holdings and Sumitomo Corporation Kyushu, began construction of the 16MW/70MWh Denki no Eki Isahaya grid-scale battery storage facility in Isahaya City, Nagasaki Prefecture, the companies announced on October 28, 2026.
According to the statement, the facility will be built on the site of a former JR Kyushu railway substation and adjacent land, using its existing grid connection capacity. It will use 14 containerized battery systems supplied by an undisclosed manufacturer. Commercial operation is expected to begin in December 2028.
JR Kyushu and the trading company’s battery storage ownership and Kyushu units launched Denki no Eki in April 2023 to develop grid-scale battery storage on the railway operator’s unutilized land. The joint venture handles development, maintenance, and operation of the facilities.
Denki no Eki Isahaya is the company’s third and largest asset, and its first extra high-voltage facility. It follows the METI-subsidized 1.5MW/6MWh Denki no Eki Kawashiri, which was commissioned in September 2024, and the 1.5MW/6.3MWh Denki no Eki Tomiai that was brought online in March 2026. Both are located in Kumamoto Prefecture. The companies said they plan to continue developing grid-scale storage along railway lines and idle sites across Kyushu.
Sumitomo Corporation has also been developing grid-scale battery storage directly. Most recently, it secured project finance for a long-term decarbonization auction contract-backed 62MW/291MWh asset in Namie Town, Fukushima Prefecture, which is expected to be commissioned in 2029.
