Tennet awards €23 billion HVDC offshore grid contracts in Dutch and German North Sea

Transmission system operator (TSO) Tennet has awarded 11 contracts worth €23 billion to three consortia to connect 22GW of offshore wind in the Dutch and German North Sea by 2031.

Tennet has awarded contracts to connect 22GW of offshore wind (Image credit: Tennet)

A joint venture (JV) between Hitachi Energy and Petrofac won a €13 billion contract covering six projects, while two ventures led by GE Renewable Energy’s Grid Solutions business secured agreements worth €10 billion.

Three of the GE contracts, totalling €6 billion, were for a venture with Singapore's Sembcorp Marine and two were for €4 billion with US-based McDermott International.

The work covers grid connection systems, including new standardised offshore platforms, onshore stations and the high-voltage direct current (HVDC) system for the two-way conversion between alternating and direct currents. 

Coming under the Dutch-German TSO’s 2GW programme, the new certified cable system enables higher transmission, with a capacity of 2GW and a voltage level of 525kV.

History-making deals

Hitachi Energy/Petrofac will provide the systems for five Dutch projects to be connected in Borssele (IJmuiden Ver Alpha, Nederwiek 1), Eemshaven (Doordewind 1 and Doordewind 2) and Geertruidenberg or Moerdijk (Nederwiek 3). The JV will also realise the German connection LanWin5, that will be connected in Rastede.

Hitachi Energy and Petrofac both said that the Tennet agreement represents the largest deal in the history of each company. 

Hitachi will supply its HVDC Light converter stations, which convert AC to DC power offshore and DC to AC onshore. Petrofac will undertake engineering, procurement, construction and installation (EPCI) of the offshore platforms and elements of the onshore converter stations.  

GE/Sembcorp will complete the work on three Dutch projects that will connect in Maasvlakte, Rotterdam (IJmuiden Ver Beta, IJmuiden Ver Gamma and Nederwiek 2). 

GE's JV with McDermott will execute the German projects BalWin4 and LanWin1, which will be connected in Unterweser. Under its agreements, GE will be responsible for the EPCI of the 2GW converter stations, using its bipolar voltage-source converter HVDC technology. 

GE Grid Solutions’ Stafford facility in the UK will manufacture the primary HVDC subsystems and equipment, while its facility in Berlin, Germany will lead overall project management. GE said it expects the contracts to result in the creation of more than 200 new jobs in the UK, France and Germany, including in its supply chain.

Sembcorp and McDermott will design, build, install and commission the offshore platforms for their respective projects. Sembcorp is currently constructing an HVDC offshore converter platform for RWE's 1,400MW Sofia offshore wind farm in the UK – again as part of a GE consortium – and one for Tennet's DolWin 5 grid connection in Germany, having acquired Keppel FELS which won the original contract as part of a joint venture with Aibel in 2019. 

Sembcorp said the latest Tennet contract is the company's largest offshore renewable project to date. 

Construction of the platforms, each comprising a 25,500t topside and a 9,500t jacket foundation structure, will commence in the third quarter of 2024 at Sembcorp Marine’s Singapore and Batam Indonesia yards. Its UK-based subsidiary, Sembmarine SLP, will be performing offshore hook-up and commissioning, including logistics and warranty support. A European office will be set up in the Netherlands.

Preparatory work is to start immediately to ensure that all the projects can be delivered by 2031, Tennet said. The TSO expects contracts for BalWin3 and LanWin4, both connecting to the onshore grid in Wilhemshaven, and LanWin2 (connecting in Heide) to be awarded soon. 

Blueprint for the future

“This is one of the most important infrastructure projects of the century,” said Tim Meyerjürgens, chief operating officer at Tennet. He said that the acceleration of offshore grid development was crucial for delivering Europe’s green energy transition. 

Marco Kuijpers, director of large offshore projects at Tennet, noted that the "new long-term approach goes hand-in-hand with a fundamental change in values towards a strong partnership". He added that taking a longer-term view enabled more flexibility, technological progress and planning security. "This benefits all parties and secures employment, growth, and the strengthening of supply chains.”  

Tennet is responsible for grid-connecting 40GW of offshore wind capacity in the German and Dutch North Sea (20GW each). This accounts for around two-thirds of the 65GW by 2030 offshore wind target agreed by Germany, the Netherlands, Denmark and Belgium in the May 2022 Esbjerg Declaration at the North Sea Energy Summit.

Its 2GW programme, developed in cooperation with leading suppliers, is a global offshore standard that focuses on harmonisation and standardisation to provide “a blueprint for future offshore grid connection systems”. At the same time as enabling faster deployment, the larger capacity of the 2GW-per-system programme reduces the number of grid connections required.

Last month, Tennet awarded contracts worth €3.8 billion to NKT and Prysmian to install an offshore electricity transmission cable network to connect 10GW of Dutch projects – 6GW in the IJmuiden Ver wind farm zone and 4GW for the Nederwiek Zone. 

Click here to subscribe to the grids and transmission bulletin to receive fortnightly news, analysis and comment straight to your inbox and visit our dedicated section for more grids and transmission news.

To submit a news, comment, case study or analysis idea for the grids and transmission bulletin, contact the editorial team.