Publication date: March 10, 2025 Understanding & Forecasting Wind Power Generation in Japan

Understanding & Forecasting Wind Power Generation in Japan

Shulman Advisory, in collaboration with Atmospheric G2, is excited to share our second mini-series article on understanding and forecasting wind power generation in Japan. While wind power’s contribution to Japan’s energy mix remains modest, it is steadily growing. In this article, we explore the challenges and opportunities in wind energy, with a focus on offshore developments and advancements in forecasting technologies such as the GRAF model.

Let’s take a closer look.

Although its contribution to Japan’s energy mix is still modest, the proportion that wind power has contributed has been growing steadily in recent years. As of March 2024, Japan’s installed wind capacity totals 6.2 GW, of which 5.9 GW is onshore and 0.3 GW is offshore (METI). The main areas that have observed growth in wind power deployment are Hokkaido, Tohoku and Kyushu, since these regions have strong and stable winds and greater land availability with relatively less populational density. The government’s total target for wind power capacity by 2030 is 23.6 GW (of which 17.9 GW for onshore and 5.7 GW for offshore), based on the latest published statistics (METI). 

Japan’s unique geographical characteristics offer both significant advantages and challenges for wind power. Strong seasonal winds from Siberia provide a consistent resource—especially along the Japan Sea (western) side, notably in Hokkaido. These winds are driven by the Siberian High, a powerful high-pressure system over Siberia, and the Aleutian Low, a low-pressure system near the Aleutian Islands. The pressure difference between these systems intensifies the winds. However, frequent typhoons and the persistent risk of earthquakes necessitate the design of installations that can withstand these natural disasters. Additionally, many offshore sites feature rocky, hard sea beds with steep drop-offs, which complicate the installation of fixed-bottom wind turbines. Despite these hurdles, Japan holds great potential for floating offshore projects within its Exclusive Economic Zone (EEZ) and territorial waters, which together cover approximately 4.47 million km², the sixth largest in the world.

To accelerate offshore wind development, Japan launched its first competitive tender process in 2020 under the new offshore wind law. These auctions designate specific “promotion zones” where developers can bid for project rights. In December 2024, the government announced the results of the third round of public auctions, selecting two consortiums to develop offshore wind projects in Tohoku. Given Japan’s vast marine potential and challenging seabed conditions, floating offshore wind technology is increasingly seen as a viable solution, with the first project of this type included in the third round of public auctions in 2024. To help advance this nascent sector further, the Floating Offshore Wind Renewable Energy Accelerator (FLOWRA) was established in 2024, to drive technological innovation.

Another key development influencing wind power utilization is the construction of a High-Voltage Direct Current (HVDC) subsea cable between Hokkaido and Honshu. This project aims to alleviate transmission bottlenecks by enabling the efficient transfer of renewable energy from resource-rich Hokkaido to the energy-intensive Honshu region. Hokkaido has some of Japan’s strongest wind resources, particularly offshore, but its relatively low local energy demand has historically limited large-scale deployment. By expanding grid capacity and improving connectivity between the two islands, the HVDC link will play a crucial role in facilitating offshore wind development, allowing surplus wind power from Hokkaido to be integrated into Japan’s broader energy network.

Atmospheric G2 is leveraging the latest Global High-Resolution Atmospheric Forecast (GRAF) model to track wind speeds at hub height, ensuring more accurate predictions for wind energy generation across Japan. The GRAF global weather modeling system uses high-resolution data and the MPAS model framework to predict weather activity around the globe. The first weather model to run on a GPU-accelerated supercomputer which enables increased resolution and update frequency, GRAF incorporates extensive atmospheric observations and employs machine- learning (AI) techniques to refine and optimize the data. 

GRAF is a state-of-the-art forecasting model designed to mitigate risks associated with sudden weather changes by providing high-resolution, 30-minute forecasts with hourly updates. This advanced system offers critical insights into wind conditions at 100 meters above ground—the optimal height for wind turbine operations. By accurately analyzing wind patterns, it helps optimize energy production and grid stability. As shown in the latest forecast, powerful winds are expected over northern and eastern Japan on Wednesday, March 12, 2025. These strong winds could significantly enhance both onshore and offshore wind power generation. With precise forecasting, energy providers can better anticipate fluctuations, enhance grid reliability, and maximize renewable energy output—supporting Japan’s transition to a more sustainable power future.

Shulman Advisory in collaboration with AG2 aims to provide comprehensive climate intelligence services valuable for energy trading, asset management, and risk assessment, helping our clients make informed decisions based on accurate weather forecasts and associated risks. By integrating Shulman Advisory’s strategic insights and consultancy with Atmospheric G2’s actionable, data-driven forecasts, we offer a holistic suite of services designed to enhance decision-making and operational efficiency across the energy sector. We believe this partnership holds great potential value for Japanese power market players including power traders, renewable energy developers, grid operators and more.