In June 2025, the Japanese Government amended "the Act on Promoting the Utilization of Sea Areas for the Development of Marine Renewable Energy Power Generation Facilities", thereby expanding the areas eligible for offshore wind development to include the Exclusive Economic Zone (EEZ). In addition, "the Offshore Wind Industry Vision (Second Edition): Industrial Strategy for Floating Offshore Wind", released last August, established a new target of developing 15 GW of floating offshore wind projects by 2040.
Base ports—ports designated as hubs for offshore renewable power generation facilities—are essential infrastructure for large-scale offshore wind development. These ports are designated by the Minister of Land, Infrastructure, Transport and Tourism (MLIT), and project developers may lease them for up to 30 years. Although the base port system was established in 2016 and began operation in 2020, a number of challenges have started to emerge as it has been put into practical use for offshore wind deployment. Questions have also arisen as to whether the current framework will be sufficient to support future offshore wind projects, including floating offshore wind.
This report reviews the challenges associated with the current base port system. It then assesses offshore wind potential in the waters surrounding Japan and classifies it into the following three categories:
- Bottom-fixed potential (water depths of up to 50 m);
- Floating potential mainly suited to semi-submersible and barge-type foundations (50–150 m); and
- Floating potential mainly suited to spar-type and semi-submersible foundations (150–300 m).
Based on this classification, this report identifies potential areas for offshore wind development.
The report also reviews manufacturing processes for semi-submersible and spar-type floating foundations undertaken in Europe and Japan, and examines the requirements for base ports in the construction process of floating offshore wind projects. Finally, it presents four recommendations for the future development of Japan’s base port system to support the expansion of offshore wind power.
It is hoped that the analysis and proposals presented in this report will contribute to the future development of Japan’s ports and to the expansion of offshore wind power in Japan.
<Table of Contents>
Introduction
Chapter 1 Analysis of Base Ports Designated as of 2025
1.1 Analysis of Designated Base Ports
1.2 Challenges when offshore wind power generation companies use base ports
Chapter 2 Amount of offshore wind power deployment required to achieve climate targets
2.1 Amount of offshore wind power deployment required to achieve climate targets
2.2 Offshore wind power potential by water depth
・Potential in waters shallower than 50 m, which mainly assumes deployment of bottom-fixed offshore wind power
・Potential in waters deeper than 50 m and shallower than 150 m, which mainly assumes deployment of semi-submersible-type and barge-type floating offshore wind power
・Potential in waters deeper than 150 m and shallower than 300 m, which mainly assumes deployment of spar-type and semi-submersible-type floating offshore wind power
2.3 Examination of expected annual deployment volume by type of offshore wind power
Chapter 3 Analysis of existing floating offshore wind projects
3.1 Manufacturing processes of floating offshore wind power deployed to date
・WindFloat Atlantic (Portugal: semi-submersible type)
・Demonstration of the floating offshore wind power generation system off Fukushima (Japan: semi-submersible type)
・Hywind Tampen (Norway: spar type)
・Off Goto City (Japan: spar type)
3.2 Requirements needed for future base ports
Recommendations: Toward the future of ports, which are key to expanding offshore wind power
Recommendation 1: Effective utilization of existing facilities and implementation of functional enhancements as necessary
Recommendation 2: Introduction of new mechanisms to promote collaboration among ports
Recommendation 3: Formulation of a technology development roadmap for spar-type floating offshore wind power toward the future
Recommendation 4: Establishment of a third-party leasing and subleasing system for base ports
Reference materials: Organized summary of maps of designated base ports and the background leading to designation
・Aomori Port
・Noshiro Port
・Akita Port
・Sakata Port
・Niigata Port
・Kashima Port
・Kitakyushu Port
References
