DeepWind Weekly delivers key updates on Japan’s offshore wind sector in English every week.
This article provides a full digest of the major developments in September 2025.

Contents

September 1st Week

1. Offshore wind off Akita to be re-tendered – Government revises requirements

Following Mitsubishi Corporation’s withdrawal, the Japanese government announced plans to revise tender conditions and re-launch auctions for two offshore wind zones off Yurihonjo and Noshiro/Mitane/Oga in Akita. New requirements are expected by year-end, with local leaders urging swift action.

2. Oga-Katagami-Akita offshore wind consortium sets up HQ – Certified as invited enterprise

Oga-Katagami-Akita Offshore Green Energy LLC, a consortium including JERA, has established its headquarters in Katagami City and was certified as an invited enterprise by Akita Prefecture. The project will install 21 fixed-bottom turbines (~260m tall), generating power for 300,000 households, with operation targeted for June 2028. Onshore transmission works have begun, and an O&M base will be established at Funakawa Port by March 2027.

3. Mitsui keeps Murakami-Tainai offshore wind project “on track” – Onshore works to start in October

Mitsui & Co., a partner in the Murakami-Tainai Offshore Wind Project, confirmed that onshore construction will begin in October, following delays in contractor selection. The project remains on schedule, targeting June 2029 commercial operation.

Mitsui acknowledged “cost challenges due to rising material prices and currency impacts,” but stressed that the overall timeline is intact. The project plans to install 38 turbines (total capacity 684 MW) across a 9,200-hectare sea area.

4. Aomori offshore wind faces challenges, but Tohoku Electric says “on track”

Despite Mitsubishi’s withdrawal from other projects, Tohoku Electric Power confirmed it will proceed as planned with the offshore wind project off Tsugaru and Ajigasawa in Aomori. The project, developed jointly with JERA and Green Power Investment, aims for 615 MW capacity and commercial operation in June 2030.

While acknowledging yen depreciation and rising material costs, the utility stressed ongoing efforts with partners and called for stronger national policy support.

September 2nd Week

1. Japan to mandate decommissioning cost reserves for wind power

The Ministry of Economy, Trade and Industry (METI) announced plans to require wind power operators to set aside reserves for decommissioning costs starting in FY2027. The measure aims to prevent illegal dumping of retired equipment.

2. Toyo Construction unveils subsea cable-laying vessel

Toyo Construction, in collaboration with Seki Shipbuilding Industry, showcased a cable-laying vessel and burial machine. With NEDO support, the company plans to introduce its own self-propelled vessel by FY2026, targeting improved efficiency and cost reductions in offshore wind construction.

3. Kitakyushu City to establish floating wind hub in Hibikinada

In Hibikinada, 25 fixed-bottom turbines and Japan’s first commercial floating wind project are already in operation. Kitakyushu City announced plans to develop an “industrial hub for floating wind” to serve both domestic and Asian markets.

September 3rd Week

1. Government approves additional support for awarded offshore wind projects

The Japanese government will revise auction rules to allow extended sea area usage beyond 30 years and provide additional support to prevent further withdrawals, after Mitsubishi Corporation exited due to soaring costs. This shift aims to balance fairness with national renewable energy goals.

2. Local governments urge METI for support to ensure project viability

Following Mitsubishi’s withdrawal, representatives from Niigata, Aomori, Yamagata, and Nagasaki visited METI to request support measures. They emphasized the need for stable frameworks to secure profitability amid inflation and exchange rate pressures.

3. Kansai Electric, JERA-led floating wind consortium partners with EMEC

The Floating Offshore Wind Technology Research Association (FLOWRA), including Kansai Electric and JERA, signed an MoU with the European Marine Energy Centre (EMEC) in Scotland. The collaboration will accelerate verification of floating wind technologies in real-sea environments, enhancing Japan’s innovation capacity.

September 4th Week

1. Akita businesses hit by Mitsubishi withdrawal – 72 firms affected

A recent survey by Akita Prefecture revealed that 72 local companies have been impacted by Mitsubishi Corporation’s withdrawal from offshore wind projects off the coast of Noshiro, Mitane, Oga, and Yurihonjo. Among the 298 companies surveyed, 24% reported direct or indirect effects, including 12 firms that had already made advance investments worth tens of billions of yen.

These investments ranged from manufacturing and construction to equipment procurement and service preparation. Many of the remaining 60 companies had planned projects or supply contracts in anticipation of stable demand from offshore wind development. Governor Norihisa Suzuki met with METI Minister Muto on September 19, requesting an immediate re-tendering process and flexible support for affected firms.

Governor Suzuki stressed that offshore wind projects are “national-scale initiatives with significant regional stakes,” urging the government to ensure that local businesses do not lose momentum. The national government has already begun preparing rule changes to extend sea-area usage periods and enable re-bidding, but the situation highlights the fragility of Japan’s local offshore wind supply chain.

2. Governors of Chiba & Akita urge swift re-tendering

In the wake of Mitsubishi Corporation’s withdrawal from offshore wind projects, the governors of Chiba and Akita met with METI Minister Muto to demand a swift re-tendering of the Choshi and Akita offshore wind zones. Governor Toshihito Kumagai of Chiba stressed the importance of reforming the tender framework to “ensure that projects can be completed without further withdrawals.”

During the meeting on September 18, METI responded that it would finalize revisions to the framework by year-end, aiming to balance fairness with the urgent need to stabilize Japan’s offshore wind pipeline. The ministry also emphasized that local community involvement, such as Choshi’s “Future Creation Council,” would continue to play a key role in securing social acceptance.

The request comes amid growing concerns that ultra-low auction bids, coupled with inflation and rising construction costs, undermine project viability. Both governors highlighted the need for a system that ensures stability over decades-long project lifespans.

3. Fukui’s Awara offshore wind – Economic impact estimated at ¥123B

Fukui Prefecture announced estimates that an offshore wind project off Awara, designated as a “preparation zone,” could generate ¥123 billion (USD ~820M) in economic ripple effects and create 6,880 jobs over 30 years. The project envisions a 350 MW capacity installation with total investment of ~¥484 billion.

The prefecture stressed that, unlike recent withdrawals in Akita and Chiba, no developers currently plan to exit from Awara, and local promotion activities remain on track. The estimates include benefits from construction, maintenance, and eventual decommissioning, highlighting offshore wind’s role as a regional growth driver.

Officials added that while profitability challenges remain nationwide, proactive local engagement and government support could help secure investment and anchor supply chains in Fukui.

Monthly Wrap-up

September 2025 highlighted both the challenges of Japan’s offshore wind business environment and the government’s additional support measures. Triggered by Mitsubishi Corporation’s withdrawal, re-tendering efforts accelerated in Akita and Chiba, while surveys revealed significant impacts on local supply chains. In response, the government moved to extend sea area utilization beyond 30 years and revise tender rules to ensure long-term project viability.

At the same time, regional initiatives advanced steadily. Kitakyushu announced plans for a floating wind hub at Hibikinada, while Fukui Prefecture estimated an economic ripple effect of ¥123 billion and nearly 7,000 new jobs from the planned Awara offshore wind project. These moves underscore offshore wind’s role not only as an energy source but also as a driver of local industry and employment.

On the technology front, the unveiling of a new cable-laying vessel and international collaboration between Japan’s floating wind consortium and Scotland’s EMEC reflected progress in infrastructure and R&D capacity. Even under rising costs and uncertain market conditions, Japan is pushing forward with both fixed-bottom and floating wind opportunities.

Overall, September marked a turning point where risks of project withdrawal intersected with reforms and innovation, highlighting both the challenges and opportunities for Japan’s offshore wind market going forward.

Explore more categories at DeepWind:

🔍Market Insights – Understand the latest trends and key topics in Japan’s offshore wind market
🏛️Policy & Regulations – Explore Japan’s legal frameworks, auction systems, and designated promotion zones.
🌊Projects – Get an overview of offshore wind projects across Japan’s coastal regions.
🛠️Technology & Innovation – Discover the latest technologies and innovations shaping Japan’s offshore wind sector.
💡Cost Analysis – Dive into Japan-specific LCOE insights and offshore wind cost structures.