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First bolted connection for Ørsted

Jan De Nul Group was contracted by Ørsted to transport and install 36 monopile foundations and the scour protection works around all 56 foundations for the Borkum Riffgrund 2 offshore wind farm. The cable installation works connecting the OWF to the offshore substation were also executed by Jan De Nul on behalf of TenneT. Thus, proving the efficiency of a bolted connection between MP and TP.

Germany continues to invest in green energy. By early 2019 approximately 460,000 additional households will be provided with sustainable wind-generated electricity by the Borkum Riffgrund 2 Offshore Wind Farm. Borkum Riffgrund 2 counts 56 Vestas turbines of 8MW each, resulting in a total capacity of 450 MW. Twenty turbines were installed on 50-metre-high jackets with 10-metre-high suction buckets. Thirty-six other turbines were placed on top of monopile foundations.

In the summer of 2016, the owner and developer Ørsted Wind Power A/S awarded the contract for the installation of the monopile foundations to the Jan De Nul Group.

The scope comprised the temporary storage, transport and installation of 36 monopile foundations (MPs), 36 Transition Pieces (TPs) bolted on top of the MPs, and the anode cages. The Jan De Nul Group was also responsible for the supply, transport and installation of scour protection around the 36 MPs and around the 20 Suction Bucket Jackets foundations.

Jan De Nul Group also carried out the cable installation, which connects the Borkum Riffgrund 2 Offshore Wind Farm to the onshore grid. This project was successfully completed in mid-June 2018, for TenneT, the power supplier.

Borkum Riffgrund 2 is being developed off the coast in the German Exclusive Economic Zone (EEZ), 17km east of the Dutch border, 34km north of the island of Borkum and 54km north-west of the German mainland. The windfarm is one of several located within a cluster of projects, in an area especially designated for offshore wind energy production (Vorranggebiet Windenergie). It is surrounded by the operational Borkum Riffgrund 1 and Trianel Windpark Borkum offshore wind farms, all three are connected through the DolWin alpha and gamma substations to the German onshore TenneT grid.

‘Think before you act’

Each offshore wind project is different and has its own challenges. It is imperative to think before putting anything into action. Jan De Nul Group started designing and manufacturing one year before the actual installation. This solid preparation resulted in a flawless collaboration, with the client and subcontractors, and thus, in a safe installation process.

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