Offshore array cables

Offshore array cables

The DBS Projects’ offshore array cables and platforms are required to transfer and transform energy collected by wind turbines.

Array cables

Array cables collect power produced at the wind turbines and transport it to offshore substations, creating a central location where power from multiple turbines can be gathered and then transported onshore.

DBS array cable figures

  • The maximum potential length of the array cables would be 650km. 325km at DBS East and 325km at DBS West.
  • The indicative external cable diameter is expected to be up to 220mm at both sites.
  • The maximum array cable voltage would be 132kV.

After being transported to the offshore substations the power is then transmitted to a landfall point.

Offshore export cable route

An offshore export cable corridor would connect the array areas with land at the coast using the offshore substations as a central transmission point. The area where offshore cables and onshore cables meet is called the ‘landfall point’ and would be located near Skipsea. The landfall point is a crucial part of the electricity’s journey from the arrays to the national grid.

Offshore cable corridor scenarios

The electricity generated by the offshore turbines would be carried from the offshore substations located within the array areas via offshore export cables to the coast.

The offshore export cables would be buried where possible in the seabed in corridors up to 1 kilometre wide, with up to six cables linking the array areas to a shared landfall location (a maximum of four power cables and two fibre optic cables). Offshore the fibre optic cables are bundled with the power cables (and installed simultaneously) but will require their own Horizontal Directional Drill (HDD) at landfall.

These cables will share a single corridor in the nearshore area and diverge to two corridors, each 1km wide, in the offshore area to reach the individual offshore substations required by each Project.

The cable route options would have a maximum offshore cable corridor length of 188km for DBS East and 153km for DBS West.

For the purpose of the DCO application and environmental assessment, an offshore export cable corridor has been defined that encompasses all required cables. The precise location of the cables will be decided at a later stage and will be within this corridor.

Indicative image of offshore export cable routes.

Indicative image of offshore export cable routes.

Offshore array

DBS is made up of two separate sites, DBS East and DBS West, which are located over 100km off the northeast coast of England at the shallow offshore area known as Dogger Bank.

Based on an estimated combined capacity of 3GW, the DBS Projects could be capable of generating enough electricity to meet the average annual domestic energy needs of around 3 million typical UK homes.*

*Calculation based on 2021 generation, and assuming average (mean) annual household consumption of 3,509 kWh, based on latest statistics from Department of Energy Security and Net Zero (Subnational Electricity and Gas Consumption Statistics Regional and Local Authority, Great Britain, 2021. Mean domestic electricity consumption (kWh per meter) by country/region, Great Britain, 2021.

The offshore arrays consist of:

  • Wind turbines and foundations
  • Array cables
  • Offshore platforms and substations
  • Inter-platform cables linking the two arrays

The exact wind turbine layout will not be finalised until much closer to the time of construction, following completion of survey work, site investigations and to accommodate the ongoing rapid development in wind turbine technology.

Turbine blade being installed at Triton Knoll

This map shows the indicative areas for DBS’s wind farm arrays. The array areas are located over 100km off the northeast coast of England, within the boundaries of the Dogger Bank Special Area of Conservation (SAC) and Southern North Sea SAC. It is anticipated that each project would be c.300km2 when the project design is ready for construction.

Offshore platforms and substations

There would be up to eight offshore platforms, including six offshore substations evenly split across the DBS East and DBS West sites, an accommodation platform which could be in either array and an electrical switching platform which could be in the arrays or along the cable route.

Offshore substations are needed to transform and transfer the energy collected by the wind turbines. At DBS there were two options for the power generated by the wind turbines - to be transformed to a higher AC voltage of up to 275kB (high voltage alternating current) or 525kV (high voltage direct current). HVAC and HVDC are two different ways to transmit electrical power through cabling.

In November 2023, we announced that we will progress with the HVDC transmission systems only, which reduces the number of offshore export cables and platforms required compared with the requirements of an HVAC system. This is in line with advice received from Natural England to help minimise environmental impacts.

Further details about the offshore elements of the projects can be found in the PEIR Chapters 8 - 17 below:

Chapter 8 - Marine Physical Environment Chapter 9 – Benthic Habitats Chapter 10 – Fish and Shellfish Ecology Chapter 11 – Marine Mammals Chapter 12 – Offshore Ornithology Chapter 13 – Commercial Fisheries Chapter 14 – Shipping and Navigation Chapter 15 – Aviation and Radar Chapter 16 – Infrastructure and Other Users Chapter 17 – Offshore Archaeology and Cultural Heritage

Indicative example of an offshore substation