The Nemo Link interconnector will diversify the electric supply of the UK and Belgium. Credit: Business Wire.
Power System's (a subsidiary of Sumitomo Electric Industries) HVDC XLPE insulated cable system will be used for the first time at DC 400kV for the Nemo Link interconnector. Credit: Business Wire.
Up to 130km of subsea cables and 11km of onshore underground cables will be laid as part of the Nemo Link Interconnector project. Credit: Elia System Operator.

The Nemo Link Interconnector is a proposed electricity transmission cable to be laid between the United Kingdom and Belgium. The project primarily involves the installation of 141km-long subsea and onshore underground cables, as well as the construction of a converter station and electricity substation in both countries.

The project is being developed by Nemo Link, a joint venture (JV) between a subsidiary of National Grid, the system operator for Great Britain, National Grid Nemo Link and Belgium’s transmission system operator Elia. The JV agreement to build the interconnector was formally signed in February 2015.

Nemo will connect the electricity systems of the two countries and enable the bi-directional flow of electricity derived from renewable sources, diversifying the electric supply systems of both countries. It will provide 1,000MW (1GW) of power capacity, which will be sufficient to serve 500,000 homes

Engineering design and site preparation for the project are expected to begin in late 2015, while the interconnector is scheduled to begin commercial operation in early 2019.

Project background

The Blackfriars solar bridge, located across the River Thames in London, was opened in January 2014.

Nemo Link Interconnector is one of 248 key energy infrastructure projects in the European Commission’s list of Projects of Common Interest (PCI), announced in October 2013. These projects will benefit from faster permit granting procedures and easier access to the European Union’s Connecting Europe Facility (CEF), which provides financial support.

An application for the electricity interconnector licence was submitted by Nemo Link to the Gas and Electricity Markets Authority (Ofgem) in December 2012 and approved in March 2013. As the subsea cable would pass through the waters of Belgium, France and the UK, the planning and consent applications for the project were submitted to the respective authorities of these countries in December 2012 and were subsequently approved in the first half of 2014.

It will be the fifth facility of its kind connecting the UK and Europe. The other operating interconnectors include the 2GW Interconnexion France Angleterre (IFA) link to France, the 1GW BritNed link to the Netherlands and the two 500MW interconnectors linking Northern Ireland and Ireland.

Details of the Nemo Link Interconnector cable route

“The overall length of the subsea cable route will be 130km, whereas the cable route onshore will be 11km long.”

The overall length of the subsea cable route will be 130km, whereas the cable route onshore will be 11km long (2km in England and 9km in Belgium).

The converter stations will convert the high-voltage alternating current (HVAC) into high-voltage direct current (HVDC) and vice-versa, using self-commutated voltage source converters in a modular multilevel converter (VSC-MMC) arrangement. The substations will connect the converter stations to the national electricity grids.

The subsea cable system earmarked for the project is J-Power System’s (a subsidiary of Sumitomo Electric Industries) HVDC cross-linked polyethylene (XLPE) cable system, the world’s first insulated cable of its kind at DC 400kV.

Details of the converter stations and substations

“The HVDC 400kV converter station and the 400kV electricity substation in the UK are proposed to be constructed on the 8ha site of the decommissioned Richborough Power Station in Kent.”

The HVDC 400kV converter station and the 400kV electricity substation in the UK are proposed to be constructed on the 8ha site of the decommissioned Richborough Power Station in Kent. The site is part of the proposed Richborough Energy Park, which aims at transforming the site into a new hub for green energy production.

The new converter station will include a main building, which will house the HVDC electrical equipment as well as the power electronics equipment to convert AC into DC and vice-versa. The station will also include a service building, storage building, single-phase converter transformers, mechanically-switched capacitor (MSC) compound, shunt reactor, outdoor HV electrical equipment, distribution network operator substation and back-up diesel generator.

The turbine hall of the former power station is expected to be reused to form part of the main converter building. The three cooling towers and chimney of the former station were demolished in March 2012 and preparation works at the site began in early 2015.

The substation will integrate both indoor and outdoor facilities, developed on an area of approximately 2.65ha, west of the converter station. The major components of the substation will include a gas-insulated switchgear (GIS) hall, outdoor gas-insulated busbars (GIB), a couple of supergrid transformers (SGTs), an MSC and a static var compensator (SVC), overhead line gantries and an amenities building.

The HVDC 400kV converter station in Belgium is proposed to be constructed on a greenfield site adjacent to the Electrabel power plant, within the Herdersbrug industry zone in Bruges, near Zeebrugge. It will be connected to the Belgian transmission system via the Gezelle substation, which is being constructed by Elia as part of the Stevin project.

Contractors involved with Nemo Link Interconnector

The contract for the construction of both the converter stations was awarded to Siemens. The combined value of the contracts awarded to Siemens and J-Power Systems in June 2015 is approximately €500m ($562m). The contract awarded to Siemens also includes a five-year service and maintenance agreement.

NRI Energy Technology