For the development of offshore wind power generation - Domestic research trends and current status in the field of wind and ocean conditions, and the ideal state of industry-government-academia collaboration (Part 1)

Rera Tech Inc., a research and development venture spun out of Kobe University, is working to build a bridge between academia and industry. Although wind power generation will play a major role in achieving carbon neutrality by 2050, the industry is still in its infancy compared to the European market. 

This time, we invited Professor Teruo Osawa (Wind Conditions Division, Rera Tech Inc.'s Technical Advisor) and Assistant Professor Yasushi Fujiwara (Ocean Meteorology Division) from the Graduate School of Maritime Sciences, Kobe University, to hold a roundtable discussion with Rera Tech Inc. and Kobe University academic researchers Konagaya and Misaki. The theme was "The current state and issues of research into offshore wind power generation in Japan, and the importance of industry-government-academia collaboration." Rera Tech Media will be delivering the contents of the discussion in two parts, the first and second parts. 

2025 Latest Edition: Kobe University and Rera Tech's Research Trends on Offshore Wind Power Generation 

A study to measure offshore turbulence intensity (wind conditions)

Osawa:There is currently a movement in Japan to expand the area of ​​offshore wind power development to the exclusive economic zone (EEZ). The challenge is how to observe wind in ocean areas hundreds of kilometers away from land. 

In Europe, observations using floating lidars are progressing,Offshore Wind Accelerator (OWA)The European Union is working to standardize it internationally. However, it is difficult to apply the European standards as they are to areas such as Japan, where typhoons occur frequently, or to the vast ocean areas of the Pacific Ocean. 

Currently, our laboratory is researching turbulence intensity, one of the challenges in observations using a floating lidar. In ocean areas with high turbulence intensity, wind turbines that can withstand the turbulence are needed, but the technology to accurately measure turbulence intensity with a floating lidar is not yet sufficient. 

To establish this technology, we are working on two things: "Developing an algorithm to bring the observation values ​​of a vertical LIDAR that swings over the ocean closer to those of a fixed vertical LIDAR" and "Developing an algorithm to convert the observation values ​​of a vertical LIDAR into those of an industry-standard cup anemometer." 

Study of the interaction between waves and wind (ocean conditions)

Fujiwara:My research focuses on the role of waves in ocean-atmosphere interactions. Waves are not only subject to wind, but can also affect the wind and ocean environments by changing wind conditions and ocean conditions such as sea surface temperature, thereby affecting wind behavior.

There are many unknowns about these processes, and we are conducting basic research centered on numerical simulations to uncover these and improve the accuracy of forecasts of oceanographic and meteorological phenomena. 

While I am conducting basic research into changes in wind and ocean currents caused by waves and their interactions, I have recently been getting more opportunities to be involved in applied research and actual development sites. In research related to offshore wind power generation, I am working with students from Kobe University to analyze wave observation data and evaluate the performance of the latest simulation technology to improve the accuracy of wave predictions. 

In the future, I would like to continue to conduct research that bridges the gap between basic research and applied research. 

Research and development directly linked to the field through industry-academia collaboration

Misaki:In parallel with these research projects at Kobe University, Rera Tech Inc. is taking a more practical approach to solving on-site problems in wind condition surveys. Recently, there is an urgent need to research and develop new survey methods such as floating lidars. 

For example, choosing the location to install wind observation equipment is an important issue, and although the guidelines provide a general guideline, they do not clearly state specific instructions. We receive many inquiries about this issue from power generation companies. In the future, we would like to make specific proposals for observation methods and installation locations, and verify their validity. 

Konagaya:Supporting the introduction of floating offshore wind power generation is one of Rera Tech's mid- to long-term goals, and we would like to focus on related research and development. Research into floating rider correction methods, which Professor Osawa mentioned, is also an important theme. 

When the observation methods and technologies developed are put into operation in the field, new challenges emerge one after another.Offshore Wind Observation Guidebook (Published in 2023)The dual scanning lidar observation technology established in the 2011 Symposium on Wind Energy Utilization still has many issues to be addressed.^{(※ 1)}However, there was much discussion about the correction methods and methods for verifying accuracy. 

As issues like these become more concrete, new research themes will likely emerge. We believe that our role going forward will be to focus on the potential of diverse observation technologies, respond to them in practical terms, and make more effective proposals. 

*1 Wind Energy Utilization Symposium 
Refers to the 2024th Wind Energy Utilization Symposium held on November 11th and 28th, 29. 
The symposium participation report of Relatec members is here. 

Challenges arising from Japan's unique weather conditions

Osawa:In the field of wind conditions, research into wakes, where wind that hits a wind turbine causes turbulence and slows down behind the turbine, is a hot topic. The impact of wind turbine wakes is large offshore, making it more difficult than on land to study how to maximize power generation as a whole wind farm and reduce loads caused by wake turbulence.

The atmosphere around Japan is unstable and turbulent due to the influence of ocean currents such as the Kuroshio Current and the Tsushima Warm Current. In this environment, wakes may be more likely to disappear than in the North Sea of ​​Europe, but Japan does not yet have any large-scale wind farms, so there are limited opportunities to actually observe these effects. 

At the recent symposium, many related studies were presented, and the main focus of the discussion was on accurately evaluating the wake effects and considering the placement of wind turbines suitable for Japan's climate. Over the next five to ten years, it seems likely that research in our laboratory will also shift in the direction of considering how to take the wake effects into account.

Furthermore, the impact of typhoons is a major issue. In Japan, while designs that can withstand typhoons are required, the normal wind speed is weaker than in Europe, so it is necessary to balance the conflicting conditions of "ensuring the strength to withstand extremely strong typhoons" and "how to generate power under normal circumstances in weak winds." Increasing strength increases costs, making it a very difficult issue from the perspective of cost-effectiveness. 

Fujiwara:In the field of oceanographic phenomena, the influence of ocean currents specific to the waters around Japan is large. The fundamental difficulty is accurate measurement of the open ocean far from the shore. Ocean observation is more difficult than wind observation. For example, when using artificial satellites, the frequency of observations is not that high, and the spatial resolution at which observations can be made is also limited, so it is insufficient when more detailed information is to be obtained frequently. 

As an alternative, there is the analysis of waves and oceans through simulation, but the current situation is that it is difficult to evaluate the accuracy. I think this is a global issue. 

In addition, in the waters near Japan, ocean currents with different temperatures collide, causing rapid temperature changes, and a phenomenon known as an "ocean front" frequently occurs. In this environment, the interaction between the atmosphere and the ocean is significantly different from other ocean areas, and is even more complex. 

When performing wave and ocean simulations in this environment, the uncertainty of the simulation itself is a major issue. In the first place, it is not clear whether the accuracy of simulations obtained with current technology is sufficient for the operational purposes of offshore wind power generation. There are many aspects that cannot be understood without conducting on-site observations and evaluating the results. 

While the unique environment of the waters around Japan presents some challenges, it is also a very interesting research subject. It is important to understand the characteristics of this area and use them in the design and operation of offshore wind power generation. 

Data disclosure is essential to create a common platform and promote technological development 

Misaki:The practical difficulty in utilizing research results is how quickly to produce and publish the results. Whether it's wind conditions or sea conditions, observation data is the most important data, and how to make it public is important. 
 
However, in most cases, observational data is collected for a specific project or case, so it is often not intended to be made public, and there are cases where its use in research presentations is also restricted. It is even more difficult to make data public from actual cases, and even if you put in a lot of effort in your research, you often can only share it within your company. 

 The wind power industry is broad-based and has a wide range of stakeholders, so it is essential to confirm and adjust the use of observation data and collaborate with the many parties involved. 
 
Osawa:Lack of data is a fundamental problem facing Japan. There is extremely little available offshore wind observation data in Japan, and even in projects involving the government, the data is often kept private within the company or organization that has been commissioned to carry out the project. There is a tendency in Japan to treat data as a "high-value asset." 

 Meanwhile, data sharing systems are progressing in Europe. In Germany,FINOThis offshore research platform has erected 100-meter-class wind observation masts in the North Sea and the Baltic Sea, and has made the data it obtains available to the public free of charge. The fact that there is a common platform that can be freely used by researchers and businesses around the world is accelerating international technological development. 

Recently, the importance of sharing has begun to be recognized little by little in Japan.Mutsu Ogawara Offshore Wind Observation Test SiteThere are some efforts to open up observational data, such as the initiative for the 2016 Tohoku Earthquake and Tsunami. However, there has been little progress in disclosing other observational data. I believe this is one of the issues impeding the progress of offshore wind power generation in Japan. 

Fujiwara: The lack of data and the issue of disclosure are similar in the field of oceanography. When acquiring data, it is also important to coordinate interests with those involved in the fishing industry. In Japan, the fishing industry is deeply rooted as an important industry, so negotiations with them are essential for marine observations. 
 
Fishermen often express their concerns about the impact of the installation of observation equipment on their fishing activities. I am not directly involved in addressing this issue, but I have heard that the field of coastal oceanography has a long history of working to achieve mutual understanding and reconcile interests regarding these concerns. 
 
Recently, ocean simulation technology has made great advances, enabling more high-resolution and realistic models, and it has become possible to reproduce the movements of ocean areas near land with great precision. However, to support the accuracy of the simulation, data from coastal areas is essential. In advancing observation activities, we believe it is important to clearly explain to stakeholders, including fishermen, that there are benefits to be gained from them, and to build relationships of trust and win-win relationships. 

(Continued in Part 2: In Part 2, we will discuss the theme of "How industry, government and academia can accelerate the offshore wind market.") 

As wind condition consultants, Rera Tech Inc. will carry out optimal wind condition surveys that combine "observation" and "estimation" for wind power generation.

References 

Japan Coast Guard, Jurisdiction of the Sea Area - Japan's Territorial Waters -, Conceptual Map of Japan's Territorial Waters
https://www1.kaiho.mlit.go.jp/ryokai/ryokai_setsuzoku.html
Offshore Wind Accelerator  
https://www.carbontrust.com/en-as/our-work-and-impact/impact-stories/offshore-wind-accelerator-owa 
New Energy and Industrial Technology Development Organization (Contractor) National Institute of Advanced Industrial Science and Technology, Kobe University, Nippon Kaiji Kyokai, E&E Solutions, Japan Meteorological Corporation, Wind Power Generation Introduction Support Project Fixed-bottom Offshore Wind Farm Development Support Project Fixed-bottom Offshore Wind Farm Development Support Project (Establishment of Offshore Wind Condition Survey Method), 2019-2022 Results Report, 1.2.IV-42,2023, XNUMX 
NEDO, Offshore Wind Observation Guidebook, June 2023, 6, 
https://www.nedo.go.jp/library/fuukyou_kansoku_guidebook.html 
Camille Dubreuil-B, Knut Sponheim Seim, Ensemble methods for wake parameter calibration. 2021, Wind Europe Technology Workshop 2021 
NEDO, Marine Energy Portal Site 
http://www.todaiww3.k.u-tokyo.ac.jp/nedo_p/jp/ 
FINO 
https://www.bsh.de/EN/TOPICS/Monitoring_systems/MARNET_monitoring_network/FINO/fino_node.html 
Mutsu Ogawara Offshore Wind Observation Test Site 
https://mo-testsite.com