Renewable Energy Institute and Aegir Insights jointly released the report "Japan Fixed-Bottom Offshore Wind: Cost Drivers and the 2040 Outlook."
This report was produced as an independent research initiative and examines how Japan can accelerate the deployment of fixed-bottom offshore wind by identifying current cost gaps with Europe and exploring pathways for cost reduction through 2040. Using a detailed techno-economic model, it benchmarks Japan’s capital expenditure against a European reference case.
The analysis highlights how Japan's distinct policy environment and challenging natural conditions—such as strong seasonal weather patterns, complex seabed geology, and the need to design for earthquakes and typhoons—as well as the relative immaturity of Japan's offshore wind market, contribute to higher costs compared to Europe. By clarifying these differences, the report provides insights into where efficiencies and cost reductions may be achieved by 2040.
FOREWORD
EXECUTIVE SUMMARY
1. Introduction
1.1. Background and Problem Statement
1.2. Study Objectives
1.3. Scope and Assumptions
1.4. Structure of This Report
2. Overview of the Status in Europe and Japan
2.1. Market size & supply chain
2.2. Permitting and Cost burden
2.3. Physical Conditions
3. Methods
3.1. Model Overview
3.2. Case Definitions
3.3. Data
3.4. Integration of Japan inputs into the QuantTM model
3.5. Boundary Definitions
3.6. Scenario Design
4. Results
4.1. 2030 reference cases comparison
4.2. Main cost drivers of Japanese premium
4.3. 2040 outlook
5. Conclusions & Implications
5.1. Key Conclusions
5.2. Policy & Market Design Implications
5.3. Limitations & Future Work
REFERENCES
APPENDICES
EXECUTIVE SUMMARY
Japan's offshore wind sector stands at a crossroads. Despite the government’s project pipeline targets of 10 GW by 2030 and 30–45 GW by 2040, development remains constrained by a combination of structural physical conditions and early-stage market factors — the consequences of which are now visible in high-profile project cancellations such as Mitsubishi Corporation's withdrawal from approximately 1.7 GW across three sea areas.
To enable acceleration of fixed-bottom offshore wind in Japan, this report clarifies current cost premiums between Europe and Japan as well as the potential for cost reductions towards 2040. This is done through benchmarking of the capital expenditure (CAPEX) of fixed-bottom offshore wind in Japan against a European reference case, using the Aegir Quant™ techno-economic model. Japan's institutional framework differs materially from Europe in terms of both policy framework and physical conditions that include severe metocean seasonality, complex and highly variable seabed geology, and compounding seismic and typhoon design requirements — factors that add to engineering and construction costs relative to European conditions.
The 2030 results quantify a 21% CAPEX premium between the Japanese and European reference cases (3.91 mEUR/MW vs. 3.22 mEUR/MW). Turbine supply is the single largest cost driver, reflecting typhoon and earthquake certification requirements, while installation costs also add significantly, driven by weather downtime and hard seabed geology requiring drilling at a material share of foundation positions. Out of the total EUR 307m premium, approximately EUR 223m (≈73%) is attributable to physical and design constraints that are less directly reduced by market maturation, while EUR 84m (≈27%) reflects addressable market conditions. Additionally, Japan's grid connection cost-allocation framework, under which developers currently fund TSO substation reinforcements, adds to upfront CAPEX. This reflects a policy design choice that is open to review and addressing it could directly reduce the cost burden on developers.
By 2040, CAPEX per MW could decline by approximately 18%, led by turbine upscaling, improved vessel availability, and market maturation. However, Japan is expected to retain a structural cost premium over European markets over the long term.
These findings carry direct policy implications. While Japan’s structural physical conditions impose unavoidable cost uplifts, these are not in themselves decisively unfavorable for offshore wind development. The more addressable cost drivers relate to market maturity and institutional design. Drawing on European experience and the calculated cost-out potential towards 2040, four priority areas for Japan’s offshore wind market stand out:
- Establishing commissioning-based pipeline targets with a stable auction cadence to enable supply-chain investment in vessels, ports, and workforce.
- Strengthening contractual and policy frameworks to absorb post-auction economic shocks.
- Reviewing the grid connection cost-allocation framework, where requiring developers to fund TSO substation reinforcements may concentrate risk on first movers and increase overall system costs.
- Addressing regulatory constraints, including cabotage rules and port land-use restrictions, that limit logistical efficiency and cost-effective project delivery.
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[Seminar] Offshore Wind at a New Stage: Policy and Institutional Design for Scalable Deployment (13 March 2026)
