Japan is accelerating the deployment of offshore wind power, and one of the most symbolic projects in this effort is the Murakami Tainai Offshore Wind Power Project. This initiative is part of the Japanese government’s second round of offshore wind power auctions—commonly known as “Round 2”—and represents a critical step toward achieving the national targets of 10 GW of offshore wind capacity by 2030 and 30–45 GW by 2040.
With a total planned capacity of 690 MW, the project will significantly contribute to the decarbonization of Japan’s energy mix through fixed-bottom offshore wind power. It is also expected to drive regional industrial development and economic revitalization. This article provides a detailed overview of the project, including its schedule and evaluation based on investment viability.
➡ For an overview of all ten Promotion Areas as of 2025, see:
Promotion Areas for Offshore Wind in Japan – 2025 Overview
1. Project Overview
| Project name | Murakami Tainai Offshore Wind |
| Developer | Murakami Tainai Offshore Wind Consortium |
| Consortium Members | Mitsui & Co., Ltd. RWE Offshore Wind Japan Murakami-Tainai K.K. Osaka Gas Co., Ltd. |
| Location | Offshore murakami and tainai City, nigata Prefecture |
| Type | Fixed-bottom Offshore Wind Power |
| WTG | GE → TBD |
| Price | 3 JPY/kWh |
| Capacity | 684 MW (18 MW × 38 turbines) → 690MW (15 MW x 46 Turbines) |
| Start of Construction | april 2025 → Oct. 2025 |
| Operation Period | june 2029 –2054 |
2. Location and Site conditions
2-1. Wind Conditions
The wind speed within the zone is approximately 6.0–7.5 m/s (at 100 m altitude).
2-2. Water Depth
The water depth within the zone is approximately 20–40 m.
2-3. Port Infrastructure
Niigata Port is expected to serve as the construction base port, and Iwafune Port is anticipated for use as the O&M port.
3. Consortium Members
Mitsui & Co., Ltd.
- A general trading company founded in 1876.
- Engaged in a wide range of business sectors, including steel products, mineral and metal resources, energy, infrastructure projects, transportation, food, retail, healthcare, and ICT. Actively investing in renewable energy businesses as well.
RWE
- Started its power generation business in Germany in 1898.
- Holds a total generation capacity of 39.3 GW, including 3.5 GW in offshore wind—ranking second globally in offshore wind capacity.
Osaka Gas Co., Ltd.
- Launched operations in 1905. Supplies city gas to approximately 5 million customers, mainly in the Kansai region (2 prefectures and 5 districts).
- Its core businesses include “Domestic Energy (Gas & Electricity),” “Overseas Energy,” and “Life & Business Solutions.”
- Contributes to a low- and decarbonized society through integrated operations, from renewable energy development to supply (serving 1.71 million low-voltage customers).
4. Project Implementation Structure
4-1. Construction Phase
4-2. Operation Phase
5. Project Timeline
5-1. Overall schedule
- January 19, 2022: 1st Statutory Council Meeting
- March 24, 2022: 2nd Statutory Council Meeting
- June 20, 2022: 3rd Statutory Council Meeting
- November 7, 2024: 4th Statutory Council Meeting
- January 20, 2026: 5th Statutory Council Meeting
- Environmental Impact Assessment: 2021 – mid-2027
- Onshore construction work: October 2025 onwards
- Offshore construction work: April 2028 onwards
- Commercial operation commencement: June 2029 (tentative)
※ The commercial operation commencement date is currently under review as part of the overall schedule, taking into account potential changes to turbine specifications as well as the possible utilization of the long-term decarbonization power source auction.
5-2. Change in the Start Date of Onshore Construction
On March 28, 2025, the following announcement was made by Murakami City, Niigata Prefecture. Start date of onshore construction date will be changed from April 2025 to around October 2025.
Regarding the start date of onshore construction for the offshore wind power project, Murakami Tainai Offshore Wind Power Co., Ltd., the project operator, has informed us that additional time is required for discussions on selecting the contractor for onshore construction. As a result, the start date will be changed from April 2025 to around October 2025.
Source: Murakami city announcement
5-3. EIA status
| 事業名称 Project name | 事業者名 Developer | 手続段階 EIA Stage | 容量 Capacity | 基数 Turbines | 出力 Rating | 更新日 Last Updated |
|---|---|---|---|---|---|---|
| （仮称）新潟県村上市及び胎内市沖洋上風力発電事業 Offshore Wind Power Project of Murakami City and Tainai City, Niigata Prefecture | 村上胎内洋上風力発電株式会社 Murakami Tainai Offshore Wind Power Generation Co., Ltd. | 準備書 EIA Draft report | 690 – 736MW | 46 | 15MW | 2026/03/10 |
Source: Environmental Impact Assessment Case Information (Ministry of the Environment, Japan)
6. LCOE and IRR Estimation
Evaluating the bankability of offshore wind projects requires close attention to key cost indicators such as LCOE (Levelized Cost of Energy) and IRR (Internal Rate of Return). However, in Japan’s Promotion Zones, detailed project-level cost information remains limited in publicly available materials. As a result, investors and developers often lack sufficient data to form a fully informed assessment.
To address this gap, DeepWind applies a proprietary cost model using representative site conditions for each project, including wind resource (capacity factor), water depth, distance to port, and distance to grid connection point. Based on these input parameters, we estimate CAPEX, OPEX, LCOE, and IRR in a consistent framework.
This approach allows us to provide a cross-project comparison of the relative economic positioning of Japan’s Promotion Zone projects.
▶ For the latest model assumptions and updated relative positioning, please refer to the cost analysis Pillar article below.
👉 Cost Realities of Japan’s Offshore Wind: Analyzing LCOE and IRR Across 12 Promotion Zones (Latest Edition)
Conclusion
The Murakami Tainai Offshore Wind Power Project is one of the largest and most symbolic projects selected in Japan’s Round 2 offshore wind auctions. With a planned capacity of 690 MW, it will play a critical role in meeting the national targets of 10 GW by 2030 and 30–45 GW by 2040, while also supporting regional economic revitalization.
To explore how this area compares nationally and understand Japan’s offshore wind roadmap, visit:
Promotion Areas for Offshore Wind in Japan – 2025 Overview —
your guide to Japan’s offshore wind Promotion Areas.
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- 🏛️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.