Hello, this is Niiake from Rera Tech Inc.. At Rera Tech Inc., I am in charge of wind condition simulation and analysis.
In the previous article, we introduced the construction of offshore wind turbines, part 1 of "About offshore wind turbine construction and types of vessels." This time, we will introduce the second part, about the vessels used in offshore wind turbine construction.
There are roughly 10 different types of vessels used to install offshore wind power generation facilities, with vessels specialized for each task playing an active role during construction and operation.
Types of ships used in offshore wind turbine construction
1. Ocean exploration vessel
When constructing offshore wind turbines, they are used to survey the seabed and conduct boring surveys to determine the type and specifications of the foundations. Oceanographic research vessels include the names "Chikyu" and "Mirai." Some of you may have heard of them before.
Source: Nippon Yusen Kabushiki Kaisha (NYK Line) signs memorandum of understanding on collaboration for geological survey vessels for offshore wind power generationhttps://www.nyk.com/news/2020/20201116_02.html
②Self-elevating platform vessel (SEP vessel)
"Self-elevating" is a system in which, after the ship arrives at its destination, it places its four legs on the seabed and jacks up the hull to raise it above the sea surface and become self-supporting. It is also commonly called an SEP ship (an acronym for Self-Elevating Platform).
It can be used in waters 10 to 65 meters deep, and is not affected even when the sea is rough and the waves are high, allowing construction work to be done in a stable position.
Source: Obayashi Corporation. SEP "Hakkaku" for the construction of offshore wind power plants completed. https://www.obayashi.co.jp/news/detail/news20230512_1.html
③Semi-submersible boat/barge
A semi-submersible is a vessel that can navigate with its hull submerged to a certain extent. It is used to transport bottom-fixed foundations and floating foundations for offshore use, and can surface and launch floating bodies in a semi-submerged state offshore, improving work efficiency.
Source: Toda Corporation Floating Offshore Wind Power Generation Project Brochure Beach Launch Vessel
④Crane ship
They generally have a crane mounted on the ship, and are specialized vessels for lifting and moving wind turbines, foundation structures, etc.
Source: Japan Workboat Association, Crane Barge http://www.s-jwa.or.jp/workvessels/set19.html
⑤ Cable installation ship
They are used for laying new undersea cables, repairing them, and removing them. Some can be buried under the seabed to prevent accidents such as bottom trawling and anchors from cutting the cables.
In deep seas, it is common for cables to be laid on the seabed along the ocean floor topography. A huge drum is installed on the deck to store the cables.
Source: Toyo Construction Notice regarding construction of cable-laying ship
https://www.toyo-const.co.jp/topics/technicalnews-15836
⑥ Offshore wind power access vessel
They serve as transportation vessels to transport workers to offshore wind farms. They are often catamaran-type vessels to allow for safe transfer even in harsh weather and sea conditions.
Source: Tokyo Kisen Co., Ltd. Offshore Wind Power Access Ship Project
http://www.tokyokisen.co.jp/service/ctv.html
The long-awaited arrival of a purely domestically produced SEP vessel
A hot topic within the industry was the world's largest SEP vessel, BLUE WIND, unveiled by Shimizu Corporation in the fall of 2022. SEP vessels are essential for the construction of offshore wind turbines, but there are still few of them in Japan.3)
Source: Shimizu Corporation The world's largest self-propelled SEP vessel supports the future of renewable energy https://www.shimz.co.jp/sep/index.html Created by the author from
Just these figures give you an idea of the scale of this ship.
BLUE WIND can transport large amounts of materials at once, so for example, seven 8MW wind turbines can be installed in 7 days, and three 10MW turbines can be installed in five days, which is roughly half the time it would take to install a conventional wind turbine.
In addition, this construction method allows for more efficient construction than conventional methods, which require dividing the support column into two and traveling back and forth between the port and the construction area. For example, a support column approximately 2 meters high, the power generation equipment to be installed at the top, and the blades approximately 90 meters long can all be installed and assembled at once.
Furthermore, as a domestically produced SEP vessel, it has been specially designed to increase its operating rate even in the high waves of the Sea of Japan in winter, and it is said that an operating rate (number of days) of 90% can be ensured.
Nearly half of the costs of offshore wind power are spent on foundations, grid connection, and installation, other than the structure itself.3)For operators, the shortened work period using the SEP vessel directly translates into reduced project costs. In fact, in May 2023, three 5MW wind turbines were installed off the coast of Nyuzen Town, Shimoniikawa District, Toyama Prefecture.4)
Recently, the Ministry of the Environment has been promoting the "2050Towards achieving carbon neutrality" is accelerating the introduction of offshore wind power generation. I hope that one day we will see the arrival of 100% domestically produced wind turbines in operation, including not only the operators and wind turbine manufacturers, but also the ships involved in their construction.
(Written by Erika Shintaku)
Links to information
3) Journal of the Japan Wind Energy Society, vol. 43, No. 3, 2019, Industrial Structure and Issues of Offshore Wind Power, p. 419-422
4) Shimizu Corporation completes world's largest SEP vessel "BLUE WIND"
https://www.shimz.co.jp/company/about/news-release/2022/2022046.html
As wind condition consultants, Rera Tech Inc. will carry out optimal wind condition surveys that combine "observation" and "estimation" for wind power generation.