Offshore Wind of Change for China
The two figures of “100 million” and “10 million” are extremely meaningful to each Chinese people. By the end of October, the total installed capacity of China Guodian Corporation surpassed 100 million kilowatts, among which wind power 10 million kilowatts, the symbolic WTG is located at Jiangsu Rudong Offshore (Intertidal) 150,000 kilowatts Large-Scale Demonstration Wind Farm.
To build offshore (intertidal) wind farm, most people have never heard about it, not to mention to see it. However, when rows of WTGs are seen in Rudong Huangang bund, with huge fans rotating and singing happily, the grand situation is amazing, and it’s really a miracle!
By its strength in wind power development field, Guodian Longyuan Jiangsu Offshore Wind Power Co., Ltd. becomes the pioneer of China offshore wind power industry. As the company’s main force—engineering construction department writes one miracle and another with its difficulty-tackling, keenly innovation and efficient team spirit.
In this September, CCTV’s program of “Go Grass-Roots” made Guodian Longyuan offshore (intertidal) 150,000killowatts large-scale demonstration project as report object of “12th Five-Year Plan” key project, and focused on the engineering construction team of Guodian Longyuan Jiangsu Offshore Wind Power Co., Ltd.
Brave enough to be the first man to “eat the crab” and make new breakthroughs
Located at intertidal zone 3-8 kilometers away from Jiangsu Rudong County Huangang bund, and with planed total installed capacity of 150,000 kilowatts, Jiangsu Rudong Offshore Wind Farm is the first national offshore (intertidal) demonstration wind power project. Compared with onshore wind power, offshore wind power is still in exploration stage. As an innovative project R&D team, engineering construction department of Guodian Longyuan Jiangsu Offshore Wind Power Co., Ltd. has no any successful experience to learn in various links from design, construction to equipment and so on, therefore the team faces one difficulty and another from staffing to technology.
In more than 10 personnel of the engineering construction department, only three to four of them are experienced in thermal power work but without experience in offshore wind power work, and the others are newly-graduates from university. Confronting with the tremendous difficulty of nearly zero starting point, the whole team just went forward bravely, they plied between intertidal zone day by day to study while exploring and practicing, investigated the actual situation of the beach, and gradually knew the hydrological conditions and law of Rudong intertidal zone very well, which laid a solid foundation for future offshore construction of the project.
Previously beach wind power in the world had always been in the stage of theoretical study, and never entered into actual operation stage. The engineering construction department visited many R&D units and design institutes, and referred to lots of data, and then proposed three kinds of intertidal wind farm plans: onshore construction, offshore construction, and both onshore and offshore construction, and the final construction plan was decided through repeated discussions and studies. By more than two years of prophase preparations such as investigations, consultations, beach experiments, computer simulation experiments and plan selection, etc., the shallow-drift aground flat-bottomed barge specific for intertidal wind power construction was developed, and the working idea of “transportation equipment by boat and moving site by construction boat when tide rises, and construction aground when tide falls” was decided, and then the offshore wind power building road in line with our national situation, hydrological, geological and costal conditions along the sea was formed.
“Grope its way” to international leading position
“Before the project, we assumed many possible difficulties and prepared solution plans, but in actual stage of operation, many unpredicted difficulties occur.” Zhang Gang, General Manager of Guodian Longyuan Jiangsu Offshore Wind Power Co., Ltd. said, “We totally wade across the stream by feeling the way!”
The construction plan of WTG base is the key technical difficulty in the project. By summarizing experience of onshore wind power construction and learning advanced construction technology abroad, the engineering construction department first tried to adopt concrete cap WTG base, but due to complicated procedures, long project duration and high cost, they immediately changed it into structural steel spider and big diameter single pile WTG base, which was firstly used in China and improved construction efficiency of WTG base a lot. During building Rudong 150,000 kilowatts intertidal demonstration wind farm, the company also firstly used large-scale single pile driving technology. There was no any mature experience of single pile construction to be learned in China, and the steel pipe pile was about 50 m long, with external diameter of 5 m, thickness of 65-100 mm and weight of over 400t. Then how to guarantee the verticality of the huge pile when driving was a serious challenge during project construction.
Then, the technical leader Zhang Leping who had accumulated rich experience in building Rudong 32 megawatts intertidal project undertook the important task. Since the geological conditions of Rudong intertidal zone were rather complicated, and the changes between soft and hard soil were big, in the process of first single pile driving, the verticality difference of pile was relatively big, which couldn’t satisfy the design requirement of 25-year WTG operation. Zhang Leping didn’t hesitate to suspend pile driving construction, and convened experts to hold study meeting. In the meeting, Zhang Leping, according to his own experience and the actual situation of pile into the soil not deep, decided to excavate the soil and the new construction plan that conducted pile driving again after pile pulling by hoist. Meanwhile, pile driving technique was adjusted a lot from many aspects like pile natural verticality hammer of initial state and pile driving penetration hammer energy and so on. Through a series of adjustments and optimizations, the verticality difference of pile decreased from 5‰ to 3‰ in later pile driving process, controlling verticality of each pile within the design requirement, which greatly improved offshore wind power construction.
Through continuous explorations and studies of engineering construction department, the company has obtained many offshore wind power construction patents such as “offshore intertidal wind power construction equipment”, “steel pipe pile construction equipment”, “steel pipe pile driving construction technique” and so on, preliminarily known the law of offshore wind power construction and mastered construction technique. Now, Longyuan power single pile driving technology level is leading nationally and advanced internationally.
Offshore Wind Chasers that “Follows the Moon”
Compared with onshore wind-farm construction, offshore wind-farm construction is even harder. At the beginning of project construction, the company employed local laborers for infrastructure construction, but the laborers didn’t manage to last for a week before they left without drawing their salary. So this can tell how unbearably awful the working environment is to common people.
Offshore construction is usually carried out at falling tide, and such a manner of working is figuratively described by Longyuan staff as “following the moon”. As morning and evening tides are affected by the moon, and rise and fall twice a day, and the tides in the next day occur about one hour later than that in the first day, that is to say, if the work starts at 03:00 AM today, it will start at 04:00 tomorrow, and so forth; and 15 days is a cycle period. In 365 days of a year, the best construction time falls on autumn and summer, and the construction time in a month is only 10 days, while the actual time in a day for driving piles for wind turbines is only two hours, so the construction procedures must go smoothly without a hitch, and if a couple of minutes are delayed, maybe the work will have to be suspended until the next tidal level.
tIn order to catch the rising and falling tides twice in a day, and the brief and precious time for construction, constructors had to eat and live aboard. The site operation was mostly tide-waiting operation and continuous operation, and sometimes the constructors had to wake up in the small hours and started to work. Such atrocious working conditions had disordered the biological clock of members of Engineering and Construction Division at the construction site. Due to the special conditions of offshore operation, water-cooled air-conditioners can not work properly when the ship was left on the beach; in the daytime, the deck was scalded by the sun, and the temperature was extremely high, so it hurt like hell when walking barefooted on the deck; at night, the sea surface temperature was low, as aloft operation required that no thick clothes be worn, it always made the workers tremble with cold. The field staffs sometimes needed to wade in the water to carry out certain operation, and the ice-cold sea water in winter made their legs go numb. Chen Qiang, Head of Engineering Construction Department once spent a solid week aboard the ship, and he said with a smile: “in the daytime, the ship feels like ‘teppanyaki’, and at night, we have nothing to do for entertainment, and we can only lie on the deck and count the stars.”
Gu Xin, a member of Engineering Construction Department once went to sea for survey, and as the time of sailing was 04:00, everyone woke up very early. When they were later on board, they were so tired that they plunged into bed and fell asleep. It was already broad daylight when Gu Xin woke up after a sound sleep, and he found the three colleagues who were lying besides him missing! He ran out to find that a young colleague was huddling up in the control cabin, whey-faced, eyes closed, teeth clenched, and wouldn’t respond to any call; another young fellow in the stern couldn’t help but keep vomiting into a vat that he was holding; and the third man was patting his back. Gu Xin went up and saw that the young fellow was spitting out nothing but black gall water. Even so, they.l kept a stiff upper lip and managed to finish the survey on schedule.
Such a group of painstaking constructers follow the pace of moon, light the lamps and candles of a myriad of families, and have accomplished one pioneering work after another, providing a testing platform for domestic wind turbines to grow to maturity, gathering valuable experience for large-scale development and construction of national offshore wind power, and pulling off the “plebification” of offshore wind power construction in Guodian Longyuan, which is called the “Noble Project” abroad.
Offshore WIND staff, December 30, 2011