Modular Offshore Grid (MOG) Submarine Cables

In 2013-2014, Elia Asset N.V has been developing an offshore HVAC grid in the Belgian North Sea to connect several wind farms to the Belgian onshore HVAC grid. IMDC got ingaged when Elia considered installation of two offshore high voltage station infrastructures (called Alpha and Beta) and a number of HVAC submarine HV-cable connections. For the Alpha OHVS an artificial island with land reclamation is the preferred option. IMDC supported Elia in the design, development and realization of the project. The main task are related to conceptual designs, basic design, design basis, follow-up of FEED studies and 2D/3D physical model tests, set-up of Employers Requirements and Functional Requirements and HS&E Requirements. 

In 2015-2016, IMDC provided further support towards new Modular Offshore Grid (MOG) concept. The MOG will group and connect the offshore produced energy of four new wind farms (Rentel, Seastar, Mermaid and Northwester 2), so that it can be injected in the Belgian onshore grid via fewer sea cables. It consists of an Offshore Switchyard Platform (OSY), the transmissions systems on the Rentel platform and three submarine connecting the platforms with the Stevin 380kV-substation in Zeebrugge. 

As Marine Consultant of ELIA for the development of the MOG, IMDC (i) performed a desktop study for the position of the Offshore Switch Yard (OSY) and export cable routing, (ii) defined the scope of work and the contractual and technical specifications for the seabed surveys, (iii) assisted in the selection of the survey contractor, (iv) managed and followed-up the surveys and (v) interpreted the factual survey data reports as input for the design basis of the OSY foundation and cables. 

IMDC has also performed Cable Burial Risk Assessment (CBRA) for MOG subsea cables with the final objective to advice on the burial depth of the cables and complementary recommendations to guarantee the recommended burial depth during the full lifetime of the project. 

The MOG is of strategic importance for Belgium’s further development of renewable energy in the North Sea. 


  • Client: Elia
  • Start date: 2013
  • Completion date: 2016