Merkur offshore wind farm, previously known as ‘MEG Offshore 1’ (MEG 1), is located in the German Exclusive Economic Zone (EEZ) in the North Sea, approximately 45 km north of Borkum Island. The project site is located directly adjacent to the wind farms Alpha Ventus, Borkum Riffgrund 1 & 2 and Trianel wind farm Borkum in water depths ranging from 27 m to 33 m. Merkur occupies an area of 47 k km2 and comprises 66, GE Haliade 150, 6 MW turbines representing a capacity of 396 MW. The turbines are connected by means of 73, 33kV inner array cables to an offshore substation which transforms the generated energy to 150 kV.
DEME Offshore's scope included the design, procurement, manufacturing, installation and commissioning of 66 foundations (including scour protection), 73 inner array cables and an offshore substation, as well as the installation of the turbines. The monopile foundations are designed with a bolted MP-TP connection and a single layer of scour protection. The monopiles were fabricated at Steelwind, Germany, while the TPs were constructed at IDESA, Spain.
Heavy Lift Jack-up Vessel ‘Innovation’ and the Jack-up Vessel ‘Thor’ loaded the monopiles and transition pieces in the port of Eemshaven in the Netherlands and transported them offshore. The offshore installation was carried out with a particular focus on noise mitigation while driving the piles.
The 73, copper-cored 33kV inner array cables measure a total length of 83 km. DEME Offshore also managed the engineering and fabrication of the cables at Prysmian, Norway, and subsequently laid the cables with the Fallpipe Vessel ‘Flintstone’, which was specially converted for the assignment. The cables were terminated and buried 1 m below the seabed with a tailor-made cable trencher deployed from the Fallpipe Vessel ‘Rollingstone’.
The unmanned, offshore substation features two transformers of 250 MW. Additionally, the jacket has a cable deck to allow cable installation before the topside is installed. Weighing 2,500 tonnes, the topside was constructed at ENGIE in Belgium, while the 1,700-tonne jacket was assembled at the Iemants site in the Netherlands. Following the offshore installation by HLV ‘Oleg Strashnov’, the substation was commissioned and taken into operation. The turbines were installed by the chartered vessel ‘Seafox 5’.