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NRG's sandcastle prevents fluid seeping out

4C Offshore | Chloe Emanuel
By: Chloe Emanuel 17/11/2023 TenneT

Contractor NRG has commenced drilling beneath the dunes for the connection of the Hollandse Kust offshore wind farm (west Beta), following initial drillings toward the Tata Steel site. The operation involves two electric drilling machines positioned in the 'Een Zee van Staal' sculpture park and on Velsen beach, set to converge at a depth of approximately 30 metres.

Creating a temporarily elevated working area on Velsen beach, contractor NRG's project leader Johannes Becker highlighted the purpose of the elevated zone. "With this 'sandcastle,' we level the height difference on either side of the dunes, preventing drilling fluid from seeping out and preparing the boreholes for TenneT's electricity cables," explained Becker.

This marks NRG's second endeavor employing intersect drilling techniques for cable landings, showcasing a scaled-down version of the previous sandcastle at Heemskerk. The initiative involves fewer drillings, rendering the sandcastle smaller in size.

TenneT's forthcoming 'socket at sea,' installed 50 kilometers off the Egmond aan Zee coast, will link wind turbines constructed by RWE in 2025. To facilitate power transmission to Velsen by 2026, contractor NBOS plans to install two seabed electricity cables, connecting them to underground sea cables behind the dunes.

NRG is overseeing the creation of six boreholes, two under the dunes and four on land, facilitating the connection of 'west Beta' to the Wijk aan Zee transformer station. TenneT's parallel laying of cables for 'west Beta,' 'north,' and 'west Alpha' will culminate in power integration into the national grid.

Utilising intersect drilling, NRG's technique involves GPS-guided drills from both the beach and the Sculpture Park work site, meeting halfway under the seabed to maintain minimal fluid pressure.

The Dutch North Sea coast's collaborative efforts have achieved 4.5 GW of offshore wind energy, surpassing 2023 goals within budget and nearly subsidy-free. With offshore wind farms supplying 15.8% of current electricity demands, the sector aims to reach 16% clean energy by 2030 without subsidies.

To access more information on subsea cables for offshore wind and interconnector projects, as well as transmission intelligence, click here.


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