Through its Japanese joint venture, Belgian marine contractor DEME has won a contract to install 21 offshore wind turbines in Japan, marking a significant milestone for the country's offshore wind sector and representing the first deployment of 15 MW-class turbines outside Europe, excluding China.

Contract Details and Scope

The contract was secured through Japan Offshore Marine, known as JOM, which is DEME's joint venture operating in Japan. The agreement covers engineering works and vessel charter for the offshore installation of 21 wind turbines as part of the Oga–Katagami–Akita Offshore Wind Project.

The contract sits within a broader arrangement between Oga Katagami Akita Offshore Green Energy LLC and Penta-Ocean Construction Co., Ltd., with JOM responsible for the offshore installation scope under that agreement.

The project is located off the coast of the Oga and Katagami areas in Akita Prefecture, a region on the northwest coast of Japan's Honshu island that has emerged as one of the country's key zones for offshore wind development.

Turbine Specification and Regional Significance

JOM will install 21 Vestas V236-15 MW turbines at the site. The selection of this turbine model carries particular significance for the Japanese offshore wind industry, as it represents the first time 15 MW-class turbines will be deployed in Japan. More broadly, the project also marks the first application of turbines of this size anywhere outside Europe, with the exception of China.

The Vestas V236-15 MW is among the most powerful commercially available offshore wind turbines currently on the market, and its introduction to the Japanese market signals a step change in the scale of technology being adopted in the country's growing offshore wind sector.

Japan's Offshore Wind Expansion

According to DEME, the project underscores Japan's steady advancement in offshore wind technology. Japan has been working to scale up its offshore wind ambitions in recent years, designating promoted zones along its coastline and awarding development rights to consortia through a structured tender process. Akita Prefecture has been among the earlier regions to see offshore wind projects progress toward the construction phase.

The involvement of DEME, one of the world's largest offshore installation contractors, through its locally established joint venture reflects the increasingly international character of Japan's offshore wind supply chain as the country moves to deploy progressively larger projects.

JOM's role in providing both engineering expertise and vessel charter services positions the joint venture as a key enabler of the installation phase for the Oga–Katagami–Akita development.

DEME's Position in Asian Markets

The award adds to DEME's growing portfolio of offshore wind work in Asian markets. The establishment of Japan Offshore Marine as a dedicated joint venture structure demonstrates the company's strategy of developing locally anchored operations to participate in markets where domestic content and partnerships carry weight in project procurement.

The joint venture model allows DEME to bring its offshore installation capabilities to bear while operating within the commercial and regulatory framework of the Japanese market.

The Oga–Katagami–Akita project represents one of the more advanced offshore wind developments in Japan, and the deployment of 15 MW turbines at the site places it at the technological frontier of what is currently being built in the offshore wind industry globally.

Turbines in the 15 MW class have only recently entered commercial deployment, with their use until now largely confined to European waters where the offshore wind industry has the longest track record and the most developed installation infrastructure.

Penta-Ocean Construction's Role

The project structure places Penta-Ocean Construction Co., Ltd. as the contracting party with Oga Katagami Akita Offshore Green Energy LLC, with JOM operating as a subcontractor to Penta-Ocean for the offshore installation scope.

Penta-Ocean is a major Japanese civil engineering and construction company with experience in marine construction, and its involvement as the primary contractor reflects the project's integration of both international offshore wind expertise and established Japanese construction capability.

The division of responsibilities, with JOM handling the engineering works and vessel charter for turbine installation, points to the specialized nature of offshore wind installation at this scale, requiring dedicated heavy-lift vessels and marine engineering expertise that JOM brings through its connection to DEME's global fleet and technical resources.

Turbine Count and Project Scale

With 21 turbines each rated at 15 MW, the project has a potential installed capacity of 315 MW, based on the turbine specifications described in the contract announcement.

The Vestas V236-15 MW turbine features a rotor diameter of 236 meters, making it one of the largest rotor diameters deployed in any offshore wind project to date and a considerable logistical undertaking for the installation vessels and crews involved.

The scale of the turbines and the total number being installed make the Oga–Katagami–Akita project a substantial undertaking by any international standard, and its execution will provide valuable experience for the Japanese offshore wind industry as it looks to build out further capacity in the years ahead.

Powering Ahead: Your Edge in the Japan Energy Race

Across Japan, the power sector is undergoing a transformation unlike anything seen in previous decades, with renewable buildouts, grid modernization programs, and large-scale generation projects reshaping the competitive landscape at a relentless pace. The organizations that move first on credible project intelligence are the ones securing the most valuable positions in this market.

Whether you are a contractor, equipment supplier, developer, or investor, staying ahead of the project pipeline means more than scanning headlines. It means knowing where capital is being committed, which tenders are live, and which contracts have already been awarded before your competitors do.

The Global Project Tracking (GPT) platform by Blackridge Research is built for exactly this purpose, delivering structured, actionable data across the full lifecycle of power projects throughout Japan, so your business development and strategy teams are always working from a position of confidence.

• Upcoming Projects

• Tender Notices

• Contract Awards

• Projects Under Construction

• Completed Projects

See the full depth of Japan's power sector intelligence for yourself. Contact the Blackridge Research team today to Book a Free Demo of the GPT platform.