7 minute read
Offshore Wind Energy Sector
The recently acquired MPI Resolution in the Van Oord colours, for the first time. (Photograph: Van Oord Offshore)
by Paul Schaap, PAS Publicaties
Once again in 2019, Dutch offshore contractors and their suppliers were closely involved worldwide in the design and construction of offshore wind farms. The best-known players in this market are Van Oord and Boskalis, both of which operate a fleet of offshore construction vessels designed specially for this task. Well-known crane operators like Heerema Marine Contractors, Seaway 7 and Allseas, and companies like Sif, HSM Offshore, Damen Shipyards, Fugro, Acta Marine and Vroon Offshore Services are however also active in this sector.
In both 2018 and 2019, Van Oord regularly hit the headlines for its role as main contractor for the construction of the Deutsche Bucht Offshore Wind Farm in the German sector of the North Sea. The first milestone in this project was reached in January 2019, when all 31 monopiles were installed by the jack-up vessel Seajacks Scylla. Each pile was 78 metres long and weighed 1,100 tonnes. Two additional monobucket foundations were subsequently installed, and the inter-array cables in the 269 MW offshore wind farm were laid by the company’s own cablelay vessel Nexus. The Nexus is equipped with the special Dig-It trencher, a tool for digging in and burying inter-array cables. The water depth at the site of this project was 40 metres. The heavy-lift vessel Aeolus was deployed to install the 33 MHI Vestas turbines, each generating 8 MW. Other special vessels involved in the project were the JB-115 from Jack-Up Barge, the accommodation vessel DP Galyna operated by Chevalier Floatels and the crane vessel Seaway Strashnov from Seaway 7. Van Oord successfully completed the work on this project at the end of 2019. In July, Van Oord announced the installation in British waters of all 102 three-legged jacket foundations
in the 714 MW East Anglia ONE Offshore Wind Farm. A special pile driving template had to be developed for this project. Van Oord then undertook the necessary installation work from the crane vessel Bokalift 1 and the jack-up vessel Seajacks Scylla. In Belgian waters, Van Oord went on to play a key role in the construction of the Northern Offshore Wind Farm. This project involved the installation of the foundations, inter-array cables, export cables and turbine elements. The scour protection was outsourced to DEME Offshore, that deployed its fallpipe vessels Flintstone and Rollingstone for this work. The Northern Offshore Wind Farm has a capacity of 370 MW, delivered by 44 MHI Vestas 8.4 MW wind turbines. In the Dutch sector of the North Sea, Van Oord started on the installation of the first monopiles for Borssele 3 and 4 at the end of October 2019. In total, 77 monopiles will have to be installed in these wind farms, together with two additional units at the Borssele 5 innovation site. The heavy-lift vessel MPI Resolution, acquired from MPI Offshore, was repainted in the Van Oord colours last March, at Damen Shiprepair, before being deployed for repair and upgrading work in the Princess Amalia Offshore Wind Farm off the coast of the Netherlands.
Heavy transport
As previously reported, the dp2 crane vessel Bokalift 1 played a key role in the transport and installation of the 102 three-legged jackets for the East Anglia ONE Offshore Wind Farm. A special template weighing 580 tonnes was used to assist in this work. Each jacket, weighing 900 tonnes, was anchored by three 150-tonne piles. The Bokalift 1, equipped with a 3,000-tonne crane, set sail from Flushing to transport five jackets and piles to the wind farm, on each trip. After completing this project, the Bokalift 1 was deployed for platform decommissioning work in the British Viking and Vulcan fields, and in the Dutch L10-AD field. The deployment of the Bokalift 1 proved so successful that Boskalis has decided to have a former drill ship converted into a dp2 crane vessel. This vessel will be rechristened the Bokalift 2, and just like the Bokalift 1 will be given a large working deck, with a surface area of 7,500 m2. Only the lifting capacity of the crane to be supplied by Huisman will be greater, at 4,000 tonnes. This announcement was made together with the announcement of the awarding of transportation and installation contract for 62 three-legged jacket foundations and the accompanying 186 pin piles in Taiwan, as part of the construction of the Changfang and Xidao offshore wind farms. For this particular project, Boskalis has signed a joint venture agreement with Hwa Chi Construction Co. In total, both wind farms will have a capacity of 600 MW. Also in Taiwan, on behalf of Yunneng Wind Power Co., Boskalis will be installing an erosion screen later this year, around 71 foundations.
After having previously laid the two 61 kilometre-long energy export cables to the Borssele Alpha transformer platform, in November Boskalis made a start on laying two of these cables to the Borssele Bèta transformer platform. The platforms in question are high-voltage substations for the Borssele 1 and 2 and Borssele 3 and 4 wind farms, respectively. The cablelay barge Giant 7, the trailing suction hopper dredger Prins der Nederlanden and the fallpipe vessel Rockpiper were deployed for this work. Elsewhere, Boskalis made a start on laying three energy export cables, with a total length of 380 kilometres, from the Hornsea 2 Offshore Wind Farm to landfall on the British coast. This work must be completed by the end of 2021. Finally, in 2019, Boskalis signed a major contract for the repair and partial replacement of the inter-array cables at another wind farm.
Crane vessels
Seaway 7 is also highly active in the offshore wind energy sector. The company was contracted by Vattenfall for the transport and installation of 76 monopiles and the installation of the inter-array cables for the Hollandse Kust Zuid 1 and 2 wind farms. Vattenfall also selected Seaway 7 for the installation of the foundations for the Hollandse Kust Zuid 3 and 4 wind farms. In April 2019, the Seaway 7, accompanied by the monohull crane vessel Seaway Strashnov, installed the jacket and the topside
The Bokalift 1 was deployed on installation work for the East Anglia ONE project. (Photograph: Boskalis)
of the Deutsche Bucht transformer platform. In early 2020, the Seaway Strashnov made a start on installing the foundations for the Triton Knoll Offshore Wind Farm. Together with the Seaway Yudin, the Seaway Strashnov will then travel to Taiwan to install foundations for the Formosa 2 Offshore Wind Farm.
For its part, Heerema Marine Contractors (HMC) was contracted for transport and installation work for the Vineyard project in the United States and for the installation of 21 foundations for the Changhua project in Taiwan. This work will be undertaken by the crane vessel Aegir. Together with Parkwind and MHI Vestas, HMC plans to deploy a revolutionary floating turbine installation method on the Arcadis Ost 1 Offshore Wind Farm.
Finally, Allseas was given a contract to install the DolWin 6 converter station, with its vessel the Pioneering Spirit. Projects in which the company is currently involved include the Hollandse Kust Zuid 3 and 4, Two Towers, Borssele 5, SeaMade, Borssele 1 and 2, Borssele 3 and 4, Triton Knoll and Vineyard windfarms. Together with Smulders, Sif is also responsible for the fabrication of foundations for a series of substations.
As concerns the design and fabrication of high-voltage substations for the offshore wind energy sector, HSM Offshore made a major contribution in both 2018 and 2019. After the yard completed the 2,900-tonne jacket in 2018, a 3,700-tonne topside was produced just one year later, for the Borssele Alpha high-voltage substation operated by TenneT. HSM Offshore worked closely with the engineering firm Iv-Oil&Gas on the design of this transformer platform. This cooperation was continued in 2019 for the design and construction of the Borssele Bèta high-voltage substation.
Others
Sif Holdings is a Dutch company that has successfully built up a positive reputation in the offshore wind energy sector, for the fabrication of monopiles and transition pieces. At the Heerema yard in Zwijndrecht, the topside for the switch yard platform was built last year for Elias. Following handover, the topside was installed on a jacket supplied previously by Heerema Vlissingen, off the coast of Belgium.
