Modular Offshore Grid

October 2018

Load out of the MOG jacket onto the barge in Vlissingen

On October 24, the jacket foundation of the offshore platform was successfully loaded onto the barge in Vlissingen.

The Jacket is 50 m tall and weighs approximately 1500 ton. The installation in the North Sea will take place during the first week of November, depending on the weather. The topside of the platform is scheduled to be installed in the second quarter of 2019.

The offshore platform is part of the MOG project and will come into service before the end of September 2019.

July 2018

Clearance of unexploded ordnance along the MOG cable route

In June, Elia carried out work on the beach at Zeebrugge as part of the Modular Offshore Grid (MOG) project. A corridor running from the beach to the offshore Elia platform had to be cleared of unexploded ordnance (UXO) before the cables could be installed. Unexploded munitions from both World Wars still remain in the coastal region today.

After using special methods to search the beach, specialised detectors and excavators were used to approach any potentially explosive objects found. All this work was carried out under the supervision of a certified UXO expert. The search for UXO at sea has also started and will continue until September of this year. In all, more than 250 objects have had to be inspected.


March 2018

Elia completes all main construction contracts for Modular Offshore Grid

Elia is pleased to announce that all main construction contracts for the Modular Offshore Grid (MOG) are in place.

Having these main contracts awarded, realisation of the MOG project is on schedule and aims for a go live by the end of September 2019. The project will be fully operational in 2020.

Via the MOG project, Elia builds an offshore electricity hub for four wind farms to bring its produced energy in the most efficient way onshore. It is the first project of its kind in Belgium and it will create opportunities for the further development of renewable energy in the North Sea.

Read the press release

Project description

The Modular Offshore Grid (MOG) is the first grid project of Elia at sea and the first of its kind in Belgium. 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.

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


Boundaries of the MOG

The following assets will be owned and operated by Elia, marked by the orange perimeter in the graph:

  • An offshore platform (OSY: Offshore Switch Yard) at approximately 40 km from the coast of Zeebrugge. It will accommodate a 220 kV substation .
  • Two 220kV submarine cables connecting the OSY platform with the Stevin substation
  • One 220kV submarine cable connecting the OSY platform with the Rentel platform and connecting the Rentel platform to the Stevin substation (= installed by Rentel and taken over by Elia)
  • The 220kV transmission assets on the Rentel platform (installed by Rentel and taken over by Elia)

The assets in the green perimeter will be owned and operated by the wind farms.

Benefits of a Modular Offshore Grid (MOG)

Compared to a direct connection (also called spaghetti concept or radial connection) to the onshore grid, the MOG offers multiple benefits.

Higher availability for the wind farms

The MOG allows maximisation of the transmission of renewable production. The total availability of the offshore wind farms connected via the MOG is higher than via an individual, direct connection:

  • The three cables between OSY and the Stevin substation can carry the full load produced by the wind farms. The MOG is therefore a more robust solution in terms of continuity. 70% of the time, the volume of wind production will not be affected by a loss or failure of one of the cables. In case of a failure, the offshore production is only reduced with full offshore production – which is only 30% of the time.
  • In contrast with the MOG, the loss of a cable of an individual direct connection means a stop and total loss of production of the associated wind farm as long as the connection is not repaired.

Allows a phased construction

Because of the modular concept of MOG, its construction can be aligned with the time schedules of the individual windfarms. This way the risk of stranded assets can be mitigated.

More cost-efficient

The total cost of both scenarios is considered similar, but with a small advantage for the MOG concept.

The MOG concept uses a common OSY platform, partially the Rentel platform, as well as three cable connections between OSY and the coast. In comparison, a spaghetti scheme does not require the OSY platform but needs 30 to 40 km more cable (approximately the distance between OSY and the coast of Zeebrugge).

More environmentally friendly

The installation of an offshore cable brings with it a number of activities that may have a local impact on environment:

  • Preparatory works: remove local obsolete telecom cables, install protection measurements at cable crossings, pre-sweeping to remove local sand dunes, local dredging and pre-trenching activities, removal of specific objects;
  • Installation and burial of the cable;
  • Offshore jointing if applicable;
  • Landfall activities (bringing the cable onshore).

The MOG contains 30km to 40km less cable than the spaghetti scheme and will to a lesser extent disturb the seabed and undersea life. Therefore it can be considered more environmentally friendly.

Future offshore development

The choice of the MOG is of strategic importance for the future of Belgium in terms of its participation in the further development of renewable energy in the North Sea.

With the direct need to connect the four wind farms in the most economic and reliable way to the onshore grid, a MOG additionally represents a unique opportunity to develop a first electric node (the so-called electricity plug or socket) in the North Sea. Only today this electric node can be realised without incurring an additional cost for the community.

Today, offshore concessions for wind farms and the associated grid reinforcements are foreseen for a capacity up to 2.2 GW by 2020. Already in 2030, projections of 4 GW might be foreseen. The construction of a MOG represents not only an advantage today, but will create valuable advantages for Belgium’s position in the future offshore development:

  1. Preparedness for more offshore production in Belgian waters.
  • Increase of capacity of the existing concessions;
  • The connection of future concessions;
  • The connection of other renewable energy sources, like wave, storage,…;
  1. A forward base for future interconnections
  • The OSY platform can be connected to nearby other offshore grid;
  • Integration of the OSY platform in a Belgian offshore grid; first building block of a future offshore supergrid.