Offshore Renewables

Jan De Nul Group provides services related to the installation of offshore wind farms, such as installation of export and inter array cables, fabrication and installation of Gravity Based Foundations, installation of scour protection rock around, and transport and installation of jacket or monopile foundations and high voltage stations. 

The combination of design and detailed engineering and all aspects of civil works, dredging and rock and marine installation enable Jan De Nul Group to offer a total package on an EPC basis. The Group’s in-house engineering department provides clients with FEED design for the selection of foundation and for all aspects of the construction and installation.

Through a constant pursuit of quality and technical innovation, Jan De Nul Group owns a very modern and well-balanced marine fleet for all stages involved in such installation. As offshore wind farm installation moves to deeper water, the cost of such foundations represent a considerable part of the total cost of the offshore wind farm and cost optimization is an essential aspect for future developments.

United Kingdom, Blyth Offshore Demonstrator

Transport from Esbjerg to the Blyth offshore windpark site of 5 MHI Vestas 8.3 MW turbines (V164-8.3 MW) and the subsequent installation with the wind turbine installation vessel Vole au vent...

Transport from Esbjerg to the Blyth offshore windpark site of 5 MHI Vestas 8.3 MW turbines (V164-8.3 MW) and the subsequent installation with the wind turbine installation vessel Vole au vent
As part of the project, Jan De Nul performed in-house the engineering and design of the seafastening structures

Key figures
Country

United Kingdom

Client's name

MHI Vestas Offshore Wind (MVOW) A/S

Contractor's role

Main Contractor

EQUIPMENT

JUV Vole au Vent

Volume

5 MHI Vestas 8.3 MW turbines (V164-8.3 MW)

Water Depth

Up to 40 m

Period

Contract: 24/04/2016-30/09/2017
Execution on site: 09.09.2017 – 30.09.2017

Finland, Tahkoluoto Offshore Windfarm

Construction of an offshore wind park (10 windmills): turbine foundations installation, including seabed preparations; wind turbine installations

Construction of an offshore wind park (10 windmills): turbine foundations installation, including seabed preparations; wind turbine installations

Key figures
Country

Finland

Client's name

Suomen Hyötytuuli Oy

Contractor's role

Main Contractor (Part JDN: 100%)

Period

04.2016 - 08.2017

Technical specs
Equipment

Dredging: BHD Mimar Sinan and SHB Tiger
Rockworks: SDB Tiger, SSDV Pompei and Crane barge DN126
Offshore: JUV Vole au Vent

Scope

2016 SCOPE:
Deliverables
Dredging Works
• Foundation dredging
• Cable route dredging
Blasting/hammering operation
Installation & Compaction of the Mass Recplacement Layers

2017 SCOPE:
Levelling layer installation and levelling works
GBF Installation
Infill GBF ballast materials
Scour protection
WTG installation
Rock backfill works on cable

Volume

Dredging: 55,000 m³ (Foundation dredging: 30,000 m³ + cable route dredging: 25,000 m³)
Rock Works: 160.000 tonnes

Soil

Loose sand/gravel, dense to very dense moraine, rock to be blasted/hammered

Belgium, Bligh Bank Phase 2 - Nobelwind OWF

The new Belgian offshore windpark Nobelwind will be installed 46 km off the coast at Zeebrugge. It will consist of 50 Vestas wind turbines of 3.3 MW each, 165 MW in total. The windpark will be...

The new Belgian offshore windpark Nobelwind will be installed 46 km off the coast at Zeebrugge. It will consist of 50 Vestas wind turbines of 3.3 MW each, 165 MW in total. The windpark will be connected to the Belgian power grid through an export cable previously installed by Jan De Nul.

Key figures
Country

Belgium

Client's name

Nobelwind NV

Contractor's role

Main Contractor

Period

01.04.2016 - 01.04.2017

Technical specs
Equipment

JUV Vole au vent, FPV Simon Stevin, FPV Tiger

Volume

50 Vestas turbines (3.3 MW)
50 Foundations (MP & TP)
1 Foundation (MP & TP) for OHVS
SRI: 83,000 ton

Waterdepth

up to 40 m

Germany, Global Tech One

Global Tech I is one of the first offshore wind farms developed in the German North Sea. The Global Tech I wind farm’s array consists of 80 wind turbines each...

Global Tech I is one of the first offshore wind farms developed in the German North Sea. The Global Tech I wind farm’s array consists of 80 wind turbines each with a capacity of 5 MW adding up to a total installed capacity of 400 MW.

 

Jan De Nul Group was contracted to install scour protection around the foundations of the offshore substation. The works were performed by the DP2 Fall Pipe Vessel Simon Stevin with its large rock carrying capacity of 32,000ton. In order to enable installation of scour protection under the center of the platform, the vessel had to approach the substation up to a minimum distance of 10 m and the inclined fall pipe had to be redesigned to fit over and in between the cross-beams of the substation.

Key figures
Country

Germany

Client's name

Global Tech I Offshore Wind GmbH

Contractor's role

Main Contractor

Technical specs
Equipment

FPV Simon Stevin

Scope

Remediation of initial scouring to original seabed by installation of a 2-layer scour protection around/under Offshore SubStation

Volume

Filter layer (initial scouring + scouring protection): 18,000 tonnes
Armour layer (scouring protection top layer): 8,000 tonnes

Water depth

40 m

United Kingdom, Gunfleet Sands OWF Contract for Rock Installation

The offshore wind farm Gunfleet Sands in the UK has a total capacity of 172 MW. Jan De Nul Group was in charge of the scour remediation around 27 foundations,...

The offshore wind farm Gunfleet Sands in the UK has a total capacity of 172 MW. Jan De Nul Group was in charge of the scour remediation around 27 foundations, export cables, and the substation. The works were executed using the vessel Tiger, equipped with an inclined fall pipe. Over 50,000 ton of rock was needed for the job.

Key figures
Country

United Kingdom

Client's name

Dong Energy Power (UK) Ltd

Contractor's role

Main Contractor

Period
March 30, 2015
Technical specs
Equipment

Inclined Fall Pipe Vessel Tiger

Volume

50,000 tonnes of 1-8" rock

Water depth

0 m to 15 m LAT

Germany, Butendiek Wind Farm

In early 2014 the construction of the German offshore wind farm Butendiek, located in...

In early 2014 the construction of the German offshore wind farm Butendiek, located in the North Sea west of Sylt, started. Butendiek comprises 80 turbines with each 3.6 MW, resulting in a total capacity of 288 MW. Jan De Nul Group was in charge of the installation of scour protection for the 80 monopiles. The rock was purchased at a Norwegian quarry. The filter rock, approximately 71,000 ton, was loaded at the quarry and installed by the Fall Pipe Vessel Simon Stevin. The armour rock, approximately 123,000 ton, was installed by the vessel Tiger. This vessel used to be a Split Hopper Barge but has been equipped with an inclined fall pipe to execute the rock installation works closely to the offshore structures.

Key figures
Country

Germany

Client's name

OWP Butendiek GmbH & Co. KG

Contractor's role

Subcontractor to Ballast Nedam NV

Period
March 30, 2015
Technical specs
Equipment

FPV Tiger

Scope

Installation of filter rock (1-3”) prior to installation of monopiles by using the vessels fall pipe.
Installation of large armour rock (40-200 kg) after installation of mono-piles by using large diameter inclined fall pipe

Volume

90,000 tonnes

Depth

20 m

Belgium, Alstom Belwind Demonstration Project

In the North Sea, in front of the Belgian coast, part of the Belwind phase 2 wind power plant is providing a laboratory and testing facility for Alstom to...

In the North Sea, in front of the Belgian coast, part of the Belwind phase 2 wind power plant is providing a laboratory and testing facility for Alstom to assess their Haliade 150-6 MW turbine with real-life offshore wind and sea conditions. Therefore a 33 kV cable had to be installed. Jan De Nul Group was in charge of the installation, burial and scour protection of the cable. The Fall Pipe Vessel Simon Stevin was mobilized for this job and was equipped with an ROV trencher to bury the cable after installation.

Key figures
Country

Belgium

Period
April 4, 2014 to August 1, 2014
Technical specs
Scope

First end pull in, cable installation, second end pull in, cable burial with trencher and rock installation (scour protection near OHVS & WTG + 2 crossings).

Equipment

CLV/FPV Simon Stevin

Volume

Cable: 1,800 m installation
Rock: 4,800 tonnes

Water depth

22 m - 32 m

Belgium, Installation of 245kV Northwind export cable

Jan De Nul Group installed the submarine export cable to connect the 215 MW Northwind wind farm off the Belgian coast to the power grid.
...

Jan De Nul Group installed the submarine export cable to connect the 215 MW Northwind wind farm off the Belgian coast to the power grid.
Before laying the cable a deep trench through the Scheur channel, one of the most heavily navigated channels in the world, needed to be dredged.  The cable itself was loaded aboard the Multipurpose Installation Vessel Willem de Vlamingh in Norway and then installed between the Belwind Platform and Zeebrugge. The 43 km long electricity cable weighs 5,050 ton. To modify this vessel for cable lay the rock installation system was replaced by a 5,400 ton capacity turntable with a diameter of 28 m and a height of over 6 m.

Key figures
Country

Belgium

Client's name

Northwind NV

Contractor's role

Main Contractor

Period
September 1, 2015

Sweden, Karehamn Wind Park

For the Karehamn offshore wind farm in the Swedish part of the Baltic Sea, 16 foundations were required for the 3 MW turbines. Jan De Nul Group was awarded the...

For the Karehamn offshore wind farm in the Swedish part of the Baltic Sea, 16 foundations were required for the 3 MW turbines. Jan De Nul Group was awarded the design, construction and installation of these foundations.

All foundations were constructed on top of two large barges in the port of Zeebrugge (Belgium) in over a period of only 5 months. Because of the varying water depths in the Baltic Sea, the height of the cylindrical part had to be uniquely designed. The height of the elements ranges from 15 to 25 m with the heaviest element weighing approximately 1,940 tons.

The seabed had been prepared before installation of the foundations.
The first half a meter of the seabed was removed.  In order to provide an even cushion layer for the foundations, a gravel layer was installed. To level the cushion layer, a levelling system has been developed by means of a levelling beam installed on the Cutter Suction Dredger Vesalius. This allowed for gravel bed foundation to be levelled within the design tolerances of 45 mm.

With the gravel bed installed and levelled, the Heavy Lift Vessel Rambiz lifted the foundations off the barges and installed the foundation to within 30 cm of the theoretical position.

After installation, they were ballasted so they could withstand the forces of waves and currents and carry the actual wind turbine. 

The shaft of the foundation was filled with magnadense crushed iron ore. The other compartments were filled with crushed iron ore, and finally a layer of heavy quarry stone was placed as a top capping layer in order to provide scour protection.

Stones of up to 130 kg were placed in the ballast caissons by means of the inclined fall pipe of the vessel Simon Stevin positioned in DP2 mode. To prevent the gravel bedding layer from being washed away, an anti-scour quarry stone layer was installed around the external edge of each foundation.

Key figures
Country

Sweden

Client's name

E.ON Vind Sverige AB

Contractor's role

EPC Contractor

Period
September 7, 2011 to April 21, 2013
Technical specs
Scope

Engineering, procurement, construction and offshore installation of 16 concrete gravity based foundations for Vestas V112 wind turbinegenerators. The foundations were poured on barges after which they were installed. The seabed had been excavated and a gravel bed been installed. Subsequently these foundations are protected from seabed erosion by means of scour protection. Heavy fill ballast such as iron ore is installed in the shaft and ballast bins. Appurtenances (J-tubes, ladders, handrails, etc) were included in the design.

Soil

Clay and sand overlaying bedrock

Volume

10,000 m³ of reinforced concrete
2,000 ton weight of GBF
5,000 m³ of seabed excavation works and gravel bed
7,000 m³ of scour protection outside GBF
50,000 ton heavy ballast fill, includes 25,000 ton iron ore based fill

Dredging depth

8 m – 21 m

Equipment

Multipurpose spudpontoon DN109, Levelling vessel Vesalius, HLV Rambiz, Transport barge DN143 (DWT 24,000 tonnes), Transport barge DN120 (DWT 10,000 tonnes),
4 Towercranes (Civil Works), 2 Mobile cranes (Civil Works)
Truck mixers & concrete pumps (Civil Works)