Facing the sea, delivering electricity to thousands of households! He is the "trendsetter" of deep-sea wind power technology

Open the map, starting from the Bohai Bay, winding all the way south along the eastern coastline to the Beibu Gulf, more than 20 major offshore wind power equipment industrial parks and bases are scattered like fruits on a vine. By the end of 2022, my country's cumulative installed capacity of offshore wind power reached 30.51 million kilowatts, continuing to lead the world. In May 2023, when fixed offshore wind turbines occupied the dominant position, my country's third built floating wind turbine prototype and the first deep-sea floating wind power platform "Haiyou Guanlan" were successfully integrated into the Wenchang Oilfield Group power grid, marking a major progress in my country's key technologies for deep-sea wind power.

▲In 2014, Gao Zhen (third row, first from right) gathered with everyone to celebrate the 70th birthdays of Professors Torgeir Moan (first row, sixth from left) and Odd Magnus Faltinsen (first row, seventh from left)

Facing the sea for more than a decade, my country's offshore wind power started from intertidal zones and shallow seas, and is now steadily advancing towards deep seas. Against the backdrop of global emission reduction and active use of renewable energy, offshore wind power has ushered in a large-scale development wave, and floating wind turbines are in the early stages of commercial development. As the main direction of energy development in the new era, the development of green renewable energy, including offshore wind power, has risen to the national strategic level. Seizing opportunities and overcoming technical bottlenecks and industrialization problems of offshore wind turbines, especially floating wind turbines, is related to the national economy and people's livelihood, and has attracted many scientific research talents to join in, continuously deepening basic research and promoting the application of new technologies.

Gao Zhen, a distinguished professor at Shanghai Jiao Tong University (hereinafter referred to as "SJTU"), a Yangtze River Chair Scholar of the Ministry of Education, and an academician of the Norwegian Academy of Technical Sciences, returned from Norway at the end of 2022 at the call of his motherland and devoted himself to the large-scale and high-quality construction of offshore wind power in my country. He independently developed ultra-large offshore wind turbines, launched new offshore installation and operation and maintenance solutions with lower costs, and rapidly promoted offshore wind power. Converting the sufficient kinetic energy of sea breeze into electrical energy and continuously delivering it to thousands of users is the original intention of Gao Zhen, an expert in offshore wind turbines.

Researching offshore, from ships to offshore wind turbines

Gao Zhen was born in Pinghu City, Zhejiang Province in 1977. After graduating from high school, he applied for the major of Naval Architecture and Ocean Engineering at Shanghai Jiao Tong University with a yearning for the blue sea. During his undergraduate studies, he ranked first all year round and was awarded the honor of Shanghai Outstanding Graduate when he graduated in 2000. Professor Gu Yongning of Shanghai Jiao Tong University was an early guide for Gao Zhen on his scientific research. "I did my undergraduate graduation project with Professor Gu, which opened up my research on load calculation and structural design of ships and offshore platforms. After that, I studied for a master's degree with Professor Gu, focusing on the numerical simulation of ship collisions and the anti-collision research of the side structure of floating production storage and offloading vessels." Professor Gu Yongning visited Norway in the 1980s and spent a year at the century-old Norwegian Classification Society. It was with his recommendation that Gao Zhen went to the Norwegian University of Science and Technology for a doctorate in 2003.

Gao Zhen's doctoral supervisor is Professor Torgeir Moan, a foreign academician of the Chinese Academy of Engineering and an expert in marine engineering. Professor Moan is the director of the Center for Ship and Ocean Structure Research (CeSOS) at the Norwegian University of Science and Technology. "The research center brings together 8 to 10 professors from different research directions such as hydrodynamics, structural mechanics and dynamics, and marine structure control theory. Everyone complements each other's strengths and cooperates in research." Norway's marine engineering research emphasizes both basic scientific research and engineering application and practice. Universities, research institutes, engineering companies, oil and gas companies, etc. work closely together to form a strong atmosphere of engineering application, which Gao Zhen was deeply influenced by during his doctoral studies. When he graduated in 2008, he won the ExxonMobil Best Doctoral Dissertation Award in the field of applied research at the Norwegian University of Science and Technology.

Gao Zhen (first from left) with his supervisor Professor Torgal Monn (first from right), his wife Jin Jingzhe (second from right) and the defense committee after his doctoral defense in 2008

Actively responding to market needs and keenly sensing changes in trends are essential qualities for excellent engineering application research experts. After graduating in 2008, Gao Zhen continued to conduct postdoctoral research at the Ship and Marine Structure Research Center. At this time, it was the early stage of commercial development of offshore wind power in Europe. "My doctoral supervisor saw the prospects. Under his leadership, relying on the research center, I carried out a series of offshore wind power research, mainly focusing on the coupling analysis of floating wind turbines." In the summer of 2011, as European offshore wind power entered the high-power era, Gao Zhen also relied on his outstanding performance to complete his postdoctoral research and officially joined the Department of Marine Engineering at the Norwegian University of Science and Technology. Since then, he has served as a researcher, part-time associate professor, and professor. At the same time, he also served as deputy department director in charge of scientific research from 2017 to 2021, and later resigned due to returning to China for development.

Outstanding contribution, awarded as a Fellow of the Norwegian Academy of Technical Sciences

There are different types and designs of foundation structures for generating electricity using offshore wind turbines, depending on the water depth. The water depth is roughly 50 to 60 meters. When the water depth is less than this value, it is more economical to use a fixed foundation structure; when the water depth is greater than this value, a floating foundation structure is required. Even if the foundation structure type is the same, the size of wind turbines with different rated powers must be designed according to the wind, waves and current conditions in different sea areas.

As offshore wind power continues to develop towards large-scale and deep sea, Gao Zhen's main research also tends to be floating wind turbines. Floating wind turbines are mainly composed of wind turbine units, towers, floating foundation structures and mooring systems. His job is to rationally design the entire floating wind turbine system to make it more efficient in power generation and safer in harsh sea conditions. In the 10 years since joining the Norwegian University of Science and Technology, Gao Zhen has presided over a number of scientific research projects funded by the Norwegian Research Council in line with international cutting-edge needs, and participated in a series of scientific research centers and projects funded by the European Union and the Norwegian Research Council. He has worked closely with the National Renewable Energy Center of the United States, Delft University of the Netherlands, the Technical University of Denmark, Statoil, and offshore wind power-related engineering companies. He participated in and promoted the transformation of the Department of Marine Engineering of the Norwegian University of Science and Technology from offshore oil and gas platform research to offshore wind turbine research, providing technical support for the development of floating wind turbines for related energy and engineering companies.

The loads and responses of offshore wind turbines (especially floating wind turbines) under the combined excitation of wind and waves show strong nonlinear and coupling effects. In order to solve the imperfections of existing design and calculation methods, Gao Zhen, his mentor and collaborators jointly proposed an integrated design method for offshore wind turbines based on the coupled analysis of wind and wave random loads and responses. The results were applied to the design of large and ultra-large (5-15 MW) floating wind turbine buoys and mooring systems. The research results solved for the first time the modeling problem of the floating wind turbine buoy structure response directly obtained by time domain calculation methods. In addition, he and his collaborators jointly proposed a single-unit overall numerical modeling method for offshore wind turbines, and promoted the application of this modeling method and numerical model in the overall design of wind turbines, local response calculation of mechanical devices and fault diagnosis. The above results have promoted the safe design, accurate calculation, safe operation and cost reduction of offshore wind turbines (especially floating wind turbines).

In the aspect of numerical simulation and application of offshore construction operations, Gao Zhen and his collaborators jointly proposed and established a method for determining the operability and safe construction window of offshore construction based on direct numerical simulation and system motion and structural response, aiming at the current situation that offshore wind turbine installation operations are mainly manual operations with poor installation efficiency and safety. They also proposed a numerical calculation method for the non-steady-state process of wind turbine components and overall offshore installation operations. In order to solve the limitations of manual installation operations, Gao Zhen and his collaborators also proposed for the first time a method to control and reduce blade motion during offshore wind turbine installation, thereby improving the efficiency and safety of wind turbine blade installation. At present, in the industry, floating wind power installation vessels have not been used for wind turbine blade installation. Based on the study of the dynamic characteristics of the self-elevating jacket installation platform, Gao Zhen used numerical simulation methods to study the dynamic characteristics of floating wind power installation vessels and the feasibility of using them for wind turbine blade installation, providing a reference for promoting the further development of offshore wind power in deepwater areas. In addition, he explored the application of machine learning methods and digital drive models in short-term wind and wave forecasting for the first time, and quantified their uncertainty and the impact on offshore installation operations. All of the above work has made offshore wind turbine construction operations more efficient and safer.

In addition, Gao Zhen is bold in innovation and active in communication. Not only does he have outstanding work in offshore wind power, his research as a whole also involves marine renewable energy, offshore operations, the application of machine learning methods and digitally driven models in the field of marine engineering, structural mechanics, dynamics and random load response analysis, as well as structural reliability and risk assessment, and he has produced outstanding results in all related areas.

Based on his outstanding contributions, Gao Zhen was elected as a member of the Norwegian Academy of Technical Sciences in 2020. At the same time, he is also the deputy editor-in-chief of Marine Structures, an international journal in the field of marine engineering, and a member of the organizing committee of several international academic conferences. From 2012 to 2018, he served as the chairman of the Offshore Renewable Energy Expert Section of the International Ship and Marine Structure Conference (ISSC). Before and after returning to China, he had published a total of 240 academic papers, including 145 journal articles and 95 conference articles. The Google Scholar search H index was 46 and the total number of citations reached 6572. At a young age, it is not easy for Gao Zhen to achieve such results in the field of marine engineering applications. After living abroad for more than 20 years, Gao Zhen couldn't help but think of the long and charming coastline in the east of the motherland and the motto of his alma mater, "Drinking water and remembering its source, loving the country and honoring the school." Since going abroad, he has hoped to return to China to serve after a successful career one day. He feels that the time is ripe.

Returning to China to promote the large-scale development of floating wind turbines

As of 2022, the global installed capacity of wind turbines is 906GW, of which 842GW is onshore wind turbines and 64GW is offshore wind turbines. China's installed capacity of wind turbines is 365GW, ranking first in the world in both onshore and offshore wind turbine installed capacity. The large-scale deployment and strong development of wind power in China has given Gao Zhen a shot in the arm for his return.

Although wind power accounts for a limited proportion of electricity use today, due to its universality and cost reduction, all countries have vigorously promoted the development of wind power, especially offshore wind power. Among them, although floating wind turbines account for a small proportion of offshore wind power, once the technical bottleneck is broken and the cost is reduced, they will be used on a large scale. "In recent years, the experience of offshore wind power development has shown that the larger the wind turbine, the lower the unit megawatt power generation cost. From the past 2-4MW, 5-8MW, to the current mainstream 10-12MW, and the 15-20MW that is being developed and tested, wind turbines are rapidly developing in the direction of large-scale." Therefore, Gao Zhen pointed out that if my country wants to transport super-large wind turbine blades and units from onshore industrial parks to offshore wind farms and quickly install them, and finally allow wind turbines to be smoothly integrated into the power grid to transmit green electricity, it must reasonably design the construction and installation process, reasonably layout the operation and maintenance, and reduce costs to achieve commercialization.

In 2020, Gao Zhen was awarded the title of Fellow of the Norwegian Academy of Technical Sciences

With a sincere desire to relieve the country's worries, in 2022 Gao Zhen was invited by his alma mater, Shanghai Jiao Tong University, to serve as a distinguished professor at the School of Naval Architecture, Ocean and Civil Engineering. In the same year, he applied for and was selected for the Yangtze River Chair Scholar Program of the Ministry of Education. Since returning to China, the issue that Gao Zhen thinks about most often is the design and analysis of offshore wind turbines, as well as the cost and efficiency in engineering applications. "My overall goal now is to improve and promote the direct application of complex and precise numerical calculations in the detailed design of wind turbines, as well as real-time applications in offshore installation and operation and maintenance, based on the existing basic engineering design and analysis methods for offshore wind turbines, to reduce the uncertainty of load, response and strength calculations, improve the accuracy of wind turbine design, and reduce the cost of wind turbines."

At Shanghai Jiao Tong University, Gao Zhen will continue to work on offshore wind turbine research, focusing on floating wind turbines while also taking into account fixed wind turbines, and establish a time domain response calculation method for wind turbines in multiple dimensions and multiple systems (wind farms, single units and power transmission devices) under the combined effects of wind, wave and flow random external loads, wind turbine control and mechanical vibration, and promote the direct application of this calculation method in wind turbine engineering design to reduce design uncertainty. In addition, he will continue to lead the team to develop a short-term forecasting method for wave and wind fields based on physical mechanics principles and machine learning joint models based on real-time measurement data, which will be used for feedforward control of ultra-large offshore wind turbines, thereby improving wind turbine efficiency and reducing wind turbine loads and responses; at the same time, the short-term wind and wave forecasting method will be combined with numerical models to conduct real-time and advanced numerical simulations for offshore wind turbine installation ships, operation and maintenance ship control and construction decisions, thereby improving the efficiency and safety of offshore construction.

As a university student, Gao Zhen stressed the need to proactively cooperate with domestic offshore wind power companies such as wind turbine designers and manufacturers, infrastructure designers and manufacturers, and operation and maintenance companies to solve practical engineering problems faced by companies and promote the implementation of results as soon as possible. At the same time, early research on other marine renewable energy sources such as floating photovoltaics, wave energy, and tidal energy should be actively carried out. "Offshore photovoltaics based on floating structures may be the second major marine renewable energy that can be commercialized on a large scale after offshore wind turbines. However, at present, floating photovoltaics can only be used in inland lakes, reservoirs, and sea areas with extremely small sea conditions around the world." Gao Zhen hopes to promote the conceptual design, numerical simulation, laboratory and offshore model tests of new (such as semi-submersible) floating photovoltaics suitable for offshore areas, and contribute to the commercialization of floating photovoltaics.

As early as when he was abroad, Gao Zhen was enthusiastic about promoting scientific research exchanges and talent training between China and Norway. He has repeatedly recommended doctoral graduates from abroad to return to China to work, and provided opportunities for domestic doctoral students and researchers to visit Norway for exchanges. Now that he has returned to China, he hopes to continue to exert his international influence and, on the existing basis, directly promote the establishment of a dual master's degree and joint doctoral training mechanism between Shanghai Jiao Tong University and the Norwegian University of Science and Technology in the discipline of marine engineering. Through his academic network in the field of international marine engineering, he provides opportunities for more outstanding Chinese scholars, actively attracts outstanding overseas Chinese scholars to return to China to work, and continuously promotes international cooperation in offshore wind power and marine renewable energy.

The scale and high-quality development of China's offshore wind power cannot be separated from the joint promotion of academia and industry. How to make more people understand and accept this emerging industry, join in, and carry out cross-collaborative research in the entire marine engineering field is worth thinking about. Gao Zhen hopes that universities can play a leading role in this, and he will continue to contribute as always.