In the "2021th Basic Energy Plan" approved by the Cabinet on October 10, 22, offshore wind power generation is positioned as "the trump card for making renewable energy the main power source," and further expansion of its introduction is expected. When formulating a business plan for an offshore wind power plant, wind condition surveys play an important role in evaluating safety and business feasibility. This time, we will explain the overview of offshore wind condition surveys and offshore wind condition observation in Japan.
What is offshore wind observation?
In wind power generation, it is essential to conduct wind condition surveys to consider wind turbine design (wind condition evaluation) and evaluate business feasibility (power generation evaluation). Offshore wind condition observation is one type of wind condition survey, and is an important factor in determining whether or not a power generation project can be carried out.
Generally speaking, a wind survey can be divided into three steps:
1. Wind observation
Observe wind using wind condition masts, Doppler lidar and other observation equipment
2. Wind condition simulation
A method to theoretically estimate wind conditions using numerical simulations. Uses CFD models, meso-meteorological model WRF, etc.
3. Wind analysis
Conducting site wind condition evaluation and power generation evaluation for wind farm certification
One of the purposes of the wind survey is to evaluate wind conditions, which calculates wind parameters necessary for wind turbine design, and a method that meets the certification guidelines is required. Another purpose is to evaluate power generation, which predicts the amount of power generation over the project period (generally about 20 years), and a highly reliable method with little uncertainty is required.
The basic method of wind observation for wind power generation is to directly observe wind conditions using an observation tower called a wind mast. Measuring wind speed and direction using a wind mast is called direct observation, and a "cup anemometer" and a "vane anemometer" are used.
However, using a wind mast to observe wind conditions offshore requires huge construction costs, and there are also issues with the time it takes to coordinate with local communities and obtain permits for installation.
The solution to these problems is expected to be indirect observation using remote sensing technology such as Doppler LIDAR. This technology is designed to enable observation at high altitudes and at sea that are impossible to achieve with wind masts, and has developed rapidly over the past decade as an alternative to wind mast observations.
Doppler LIDAR is a method of observing wind conditions using the scattering of emitted light. Particles in the air have speeds due to the influence of wind, and when a laser hits these particles, the Doppler effect occurs, which changes the wavelength of the laser. This effect is used to measure the wind speed from the change in wavelength. This observation principle is the same as the LiDAR function installed on smartphones, which measures the distance to distant objects.
This method makes it possible to measure wind conditions in the sky and over the ocean more cheaply than with conventional wind masts.Separate articleIt is explained in detail in.
There are three types of Doppler LiDAR: Vertical profile LiDAR, Scanning LiDAR, and Floating LiDAR System. Since Scanning LiDAR and Floating LiDAR are new technologies, their accuracy needs to be verified before actual observation.
Japan's progress in offshore wind observation
The first offshore wind turbines in Japan were installed in Setana Town, Hokkaido and Sakata City, Yamagata Prefecture in 2004. Since 2010, they have been installed all over the country, including in Kamisu City, Ibaraki Prefecture, Goto City, Nagasaki Prefecture, Choshi City, Chiba Prefecture, Kitakyushu City, Fukuoka Prefecture, and off the coast of Fukushima Prefecture.
Furthermore, between 2023 and 2024, new wind farms will be built in general sea areas off the coast of Nyuzen, Toyama Prefecture, as well as in port areas at Akita Port and Noshiro Port in Akita Prefecture, and Ishikari Bay New Port in Hokkaido. These will be the largest offshore wind power plants in Japan to date.
From 2025 onwards, following the expansion of facilities in Goto City, Nagasaki Prefecture, and Kamisu City, Ibaraki Prefecture, based on the Act on the Utilization of Marine Renewable Energy, operation is scheduled to begin in three areas in the first round of offshore wind power generation - offshore Noshiro City, Mitane Town, and Oga City, Akita Prefecture; offshore Yurihonjo City, Akita Prefecture; and offshore Choshi City, Chiba Prefecture (approximately 1 MW, 3 turbines) - and in four areas in the second round - offshore Oga City, Katagami City, and Akita City, Akita Prefecture; offshore Hachimine Town and Noshiro City, Akita Prefecture; offshore Murakami City and Tainai City, Niigata Prefecture; and offshore Ejima, Saikai City, Nagasaki Prefecture (approximately 1,690 MW, 134 turbines).
For more information about the infographic above here.
Promotion measures for offshore wind observation involving Relatec members
As a consultant for wind observation, including offshore wind observation, Rera Tech Inc. is involved in various initiatives with various stakeholders. Here we introduce our efforts up to now in 2024.
- New Energy and Industrial Technology Development Organization (NEDO) "Fixed-bottom offshore wind farm development support project (Establishment of offshore wind condition survey method)"
As mentioned above, direct observation using wind masts, which is the main method of observing wind conditions for wind power generation, is extremely difficult in Japan's current environment, and the use of Doppler LIDAR equipment is expected to be a solution. However, there is no standardized method for observing offshore wind conditions using Doppler LIDAR within the country, which has been a major issue.
Therefore, from 2019 to 2022, NEDO's "Fixed-bottom offshore wind farm development support project (Establishment of offshore wind condition survey method)" As part of Kobe University, Rera Tech Inc. conducted accuracy verification using multiple models, enabling us to understand the characteristics and issues of observation methods.
- Support for the creation of an offshore wind observation guidebook
As a result of the above-mentioned NEDO project, in April 2023, the first "Offshore Wind Observation Guidebook" has been released by NEDO. Rera Tech Inc. is also involved in the production of this guidebook as part of Kobe University. For more information on how to use this guidebook,Separate article
- Mutsu Ogawara Offshore Wind Observation Test Site Opening
Lidar equipment used in offshore wind power generation projects requires prior accuracy verification. However, there are no public sites in Japan where accuracy verification can be conducted, and establishing such sites was considered an urgent task.
Therefore, after the previous NEDO project, which aimed to establish methods for investigating offshore wind conditions, is completed, Mutsu Ogawara Port was selected as an official test site for the NEDO project "Model study and construction of a test site for observing offshore wind conditions" through 2023. From 2023, it will be the first test site in Japan where the accuracy of remote sensing equipment used for wind condition observation can be verified. Mutsu Ogawara Offshore Wind Observation Test Site(hereinafter referred to as "the site") has commenced operation, and facilities, equipment and systems have been established. The accuracy verification test site's facilities are open to users, and observation data from offshore wind observation masts, etc. are provided.
From 2024, Kobe University will begin independent operation of the site, where anyone can test offshore wind observation equipment.
- Mutsu-Ogawara Metocean Observation Center (MOC) established
In order to ensure the independent operation of the Mutsu Ogawara test site, we will promptly communicate with site users and ensure future developments are flexible and effective.Mutsu-Ogawara Metocean Observation Center (MOC)(abbreviated as MOC) was established. MOC consists of four companies: Relatec, Japan Weather Association, Kitanihon Kaiji Kogyo Co., Ltd., and Kobe University Innovation Co., Ltd.
The future of offshore wind observation in Japan
Japan is about 20 years behind Europe in terms of offshore wind power. We need to take the cutting-edge technology used in Europe into consideration and move forward with the development of offshore wind power that is appropriate for Japan's weather and sea conditions.
Currently, in Japan, development is focused on fixed-bottom offshore wind turbines in areas that are close to the coast and have relatively shallow waters. However, in the future, it is expected that floating offshore wind turbines will be developed in exclusive economic zones (EEZs) where the water depth will be several hundred meters.
Considering this change from the perspective of wind observation, it is expected that the distance from shore that can be observed using scanning lidar, which is the main method of observing offshore wind conditions in Japan, will be exceeded, and there is no technology to obtain data from offshore that can be recognized by certification agencies. Therefore, the establishment of technology to observe fine-scale wind conditions such as turbulence using a floating lidar system, etc., is an urgent task.
Furthermore, wind turbines have continued to grow in size in recent years, with the height to the center of the turbine (hub height) approaching 150m. Constructing a wind condition mast of this height for each project is not realistic, especially in Japan, so wind condition observation using LIDAR equipment both on land and offshore is becoming increasingly important.
Basic accuracy verification is required to check whether high-altitude observations by LIDAR equipment are accurate, but there are no high-altitude wind masts in Japan that would enable such verification. In the future, it will be necessary to introduce facilities that can be used by anyone, such as the test site.
The development and introduction of new wind observation methods using such LIDAR equipment will contribute not only to improving the accuracy of wind observation technology but also to reducing costs, and will serve as the foundation for supporting the growth of the entire offshore wind power market.
However, these developments require a huge amount of time and money, and are not straightforward. To that end, we plan to utilize the Mutsu Ogawara Offshore Wind Observation Test Site, which we maintain and operate together with Kobe University and others, as an offshore research platform, and contribute to the accuracy verification and technological development of LIDAR equipment and other technologies.
In order to promote offshore wind power generation in Japan, Rera Tech Inc. intends to continue research and development in cooperation with various stakeholders. Our efforts are not just technological innovation, but an important step toward building the energy foundation of the future. We are determined to pave the way for the future of offshore wind power generation in Japan together with all stakeholders.
reference
NEDO, Offshore Wind Observation Guidebook, 2023, URL: https://www.nedo.go.jp/library/fuukyou_kansoku_guidebook.html