What we do


The Rentel offshore wind farm is a 309 MW offshore wind concession located approximately 34 km from Zeebrugge in the Belgian North Sea. The project was developed by Rentel NV, a consortium of eight Belgian shareholders, including DEME Group, Otary Offshore Energy and Elicio NV and represents a total investment of EUR 1.1 billion.

Rentel wind farm comprises 42 Siemens turbines of 7.35 MW and supplies CO2-friendly electricity to approximately 285,000 households. The wind turbines are installed on monopile foundations and connected through 33 kV inter array cables to an offshore transformer station (OTS). The substation is connected by a 220kV submarine cable to the onshore substation of Stevin in Zeebrugge. Water depths range between 26 m and 36 m below LAT.

Pipes for Rentel Offshore wind farm


Our wide-ranging scope included the responsibility for the design of the scour protection, foundations and inter array cables; for the transport and installation of the turbines and for the offshore substation. The scour protection is a two-layer system: the filter layer was installed prior to the foundation installation and the armour layer after the pull-in and termination of the cables.

The foundations for these large turbines comprise a monopile (MP), with a weight up to 1,250 tonnes and a length up to 83 metres, and a transition piece (TP) on top with a length of 22 metres and a weight of 325 tonnes. The MP and TP are connected by a conical grouted connection.

Our heavy lift jack-up vessel ‘Innovation’ installed the foundations. However, we faced several major challenges during the installation including the handling and manipulation of the heavy and large MPs and the soil conditions were not ideal for the jacking operations and pile hammering.

We also used a single, big bubble curtain to reduce the underwater noise level during piling operations. Each of the three sections of the inter array cables were delivered in one length and cut on site. Additionally, we performed the transport and installation of the cables and the OTS foundation was transported and installed by our jack-up vessel ‘Innovation’ and the OTS topside by the heavy lift vessel ‘Rambiz’ (Scaldis).

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