NKT handshake with Guernsey Electricity

Guernsey's supply of green electricity

NKT completed turnkey cable system project on record time.

Key facts

Client:

Guernsey Electricity

Location of the project

The English Channel

Quantity of order

A turnkey 90 kV high-voltage submarine cable system

Duration

March – November 2019

Total cable route length:

37.4 km

Scope

  • Design and engineering of HVAC cable system
  • Project planning
  • Manufacturing of high-voltage cable system
  • Seafloor and UXO surveys including Pre-lay Graphnel Run operation
  • Transport of cable and accessories to site
  • Offshore installation and jointing
NKT cable pull in at Guernsey
NKT cable pull in at Jersey
NKT Victoria loading surveillance
NKT cable pull in at Guernsey
Cable loading on NKT Victoria
NKT cable pull in at Jersey
High voltage cable on turntable
Cable loading on turntable on NKT Victoria
NKT Victoria cable pull in

The project

The old transmission link between Guernsey and Jersey had to be replaced.

The Channel Islands power supply depends on the import of low carbon, low cost energy from France. When the power cable section linking Guernsey to France via Jersey failed, it was financially and environmentally inacceptable to just keep on repairing it and rely on fossil fuels for local power generation.

The new GJ1 link had to be installed rapidly to secure the supply of affordable, renewable energy for homes and businesses on the island. It was also crucial to reduce CO2 (carbon dioxide) emissions and minimize the environmental impact.

Guernsey Electricity selected NKT as partner with all the know-how needed for the production and installation of the new HV (high-voltage) cable connection. The mission was to quickly and safely reinstate integrity of the electricity grid. NKT took on the challenge, and were assigned a contract that included cable design, manufacturing, route investigation and preparation, transport, cable installation and jointing.

The solution

NKT developed a high-voltage submarine cable system to connect the islands.

To meet the very tight timeframe, we executed many preparations and operations simultaneously. We used our experience and expertise to design a solution that covered the specific requirements for efficiency and sustainability.

The cable system was manufactured in Karlskrona, Sweden, at the NKT plant fed purely on green energy. The cable is protected by double layers of armor wires and capable of transmitting power at 90 kV (kilovolt) of AC (alternating current).

The cable was loaded onto and installed by NKT Victoria. She is one of the world’s most advanced cable installation vessels, loading cable using only onshore power and running more efficiently than other cable-laying vessels at sea, reducing CO2 emissions with 55 %. She enables high precision offshore installation of HV cable systems.

Despite the typical tough sea conditions with strong tidal currents and bad visibility in the channel area, NKT safely installed the 37.4 km long cable system. The next generation cablelaying monitoring system on NKT Victoria provided real-time monitoring and data collection, ensuring optimal installation conditions. It played an important role when we replaced the GJ1 link – on budget and on record time 8 months from contract award to energization of the power link.

We have developed a very collaborative relationship with NKT on this project. This is allowing us to deliver great success in terms of the fast track nature of the project.

— Alan Bates, CEO at Guernsey Electricity

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