ROTTERDAM, the Netherlands – The Two Towers consortium’s Borssele wind farm site V in the Dutch North Sea has been fully commissioned.
The consortium consists of Van Oord, Investri Offshore, and Green Giraffe.
Located about 20 km (12 mi) off the Dutch coast, it features two Vestas 9.5 MW turbines that are expected to power 25,000 Dutch households.
The Borssele site V is designated as an innovation site within the Borssele wind farm zone.
Van Oord was contracted as the Balance of Plant contractor for this project. The company deployed a wide range of equipment at the project, including offshore installation vessel Aeolus, the trencher Dig-It and cable-laying vessel Nexus.
All the innovations at the Borssele site V have been developed by Van Oord in cooperation with other research partners. The Slip Joint is a full in-house design by the company.
On April 25, 2020, the world’s first submerged Slip Joint was installed. This is an alternative connection in a wind turbine foundation. DNV GL certified the design and manufacturing of the Slip Joint in the autumn of 2019.
The Slip Joint consists of two conical sections placed on top of each other. It is based on friction, with the weight ensuring firmness and stability. Installation takes place by sliding the wind turbine’s transition piece over the monopile, without having to use grout or bolts. Unlike standard solutions, the Slip Joint makes a submerged connection possible, allowing for a more balanced weight distribution between monopile and transition piece, according to Van Oord.
Other technologies incorporated at the site are thermally sprayed aluminium (TSA), impressed current cathodic protection optimization, and oval cable entry holes.
According to the company, TSA is a novel coating technology. By heating the material using high voltage electrical current, it can be applied to a metallic surface in a similar way as paint, while the characteristics are far more durable as it creates both a barrier and cathodic protection. This allows for a design lifetime of more than 35 years.
By testing and demonstrating these innovations the Borssele site V contributes to lowering both the levelized cost of energy and the environmental impact of offshore wind farms, the company said.
In addition, Two Towers partnered with Dutch energy company Vandebron. This partnership means that consumers can purchase their renewable electricity directly from this project.