Japan's first Order received for domestic monopile production for　large-scale offshore wind power project in general waters ―For the Offshore Wind Power Project Off Oga City, Katagami City, and Akita City, Akita Prefecture―

26 December 2025
JFE Engineering Corporation

JFE Engineering Corporation (President and CEO: Kazuyoshi Fukuda; Head Office: Chiyoda-ku, Tokyo) has received an order from Kajima Corporation (President: Hiromasa Amano; Head Office: Minato-ku, Tokyo; hereinafter "Kajima")^*1for the manufacturing and transportation of monopile-type foundations (foundation structures for offshore wind power facilities). These foundations are for the Offshore Wind Power Project Off Oga City, Katagami City, and Akita City, Akita Prefecture (hereinafter the "Project"), operated by Oga Katagami Akita Offshore Green Energy LLC (Representative Executive Officer: Atsushi Yuihara; Head Office: Akita City, Akita Prefecture)^*2.

The Project is scheduled to be the earliest to commence operations among the projects selected through a public offering under the Act on Promoting the Utilization of Sea Areas for the Development of Marine Renewable Energy Power Generation Facilities (Renewable Energy Sea Area Utilization Act). It will also be Japan's first project to adopt domestically manufactured monopiles^*3. Manufacturing will be carried out at the Kasaoka Monopile Factory^*4, JFE Engineering's facility located within the JFE Steel West Japan Works site in Kasaoka City, Okayama Prefecture, the only monopile manufacturing base in Japan.

Building on processing and welding technologies developed over more than 100 years of large-scale steel structure manufacturing, the Kasaoka Monopile Factory utilizes high-efficiency, high-quality welding technologies specifically researched and developed for ultra-thick steel materials for monopiles, together with JFE Steel's heavy-gauge steel plates for wind power generation, "J-TerraPlate®," which significantly reduces welding length. This enables stable mass production of approximately 50 ultra-large monopiles per year, each weighing around 2,500 tons.
In addition, by leveraging its expansive site for sufficient storage capacity and securing dedicated vessels for monopile transportation, the factory has established a system for flexible and on-time shipment and transportation aligned with on-site construction schedules.

Over many years of manufacturing excellence, JFE Engineering has earned strong customer trust. To meet new customer expectations in offshore wind power projects, the Company has established a comprehensive support system for offshore wind power projects, covering detailed monopile design, manufacturing, and transportation. Going forward, we will continue to play a key role in Japan's supply chain for offshore wind power projects, which are widely regarded as a cornerstone of renewable energy expansion, and contribute to the early realization of a carbon-neutral society.

*1 KAJIMA CORPORATION
*2 Oga Katagami Akita Offshore Green Energy LLC.
*3 Based on research conducted by JFE Engineering (as of December 2025)
*4 Completion of Japan's first manufacturing base of fixed-bottom foundation (monopile) for offshore wind turbines

１．Overview

Scope of work	Manufacturing and transportation of 21 monopiles (MP) and transition pieces (TP)
Construction period	January 2026 - March 2027 (manufacturing and transportation)
Scale	[MP (maximum)] Weight: Approx. 2,000 t; Diameter: 10.5 m; Plate thickness: 100 mm; Length: Approx. 80 m [TP (maximum)] Weight: Approx. 500 t; Diameter: 9.6 m; Plate thickness: 100 mm; Length: Approx. 26 m
Steel weight	Approx. 43,000 t
Steel grade	SM520C