Vattenfall Paints Norfolk Vanguard Picture

Vattenfall has issued a preliminary environmental information report revealing project details related to the 1.8GW Norfolk Vanguard offshore wind farm.

In the report, Vattenfall states that the wind farm will comprise two distinct areas, NV East and NV West, located in the southern North Sea, approximately 70km and 47km from the coast of Norfolk, respectively.

Image Source: Vattenfall

Norfolk Vanguard Ltd. is currently considering constructing the project in a single phase of 1800MW, in two phases of 900MW, or in three phases of 600MW.

As Offshore WIND reported earlier, the project would comprise between 90 and 257 wind turbines, each having a rated capacity of between 7MW and 20MW, with a total installed capacity of 1.8GW. The turbines would either all be located within NV West or across both NV East and NV West.

Due to the large size of the sites and the fact that the wind turbines may be installed in up to three phases, up to three different turbine models may be used, with each construction phase likely to use a different turbine model.

Additionally, there could be more than one type of foundation used for the project, which will be determined by a number of constraints, such as ground conditions, water depths, the turbine model used, wind conditions and market options. The preference is to consider foundation locations within water depths of 40m or less, but it may be necessary to build at locations with up to 50m of depth, Vattenfall said. The foundations would be manufactured onshore and most likely delivered to site as fully assembled units with all ancillary structures attached.

Norfolk Vanguard Ltd. is considering both a HVDC and a HVAC electrical solution for the offshore and onshore infrastructure for the project. There would me a maximum of three HVAC offshore substations, and a maximum of two HVDC solution platforms.

The report says that the maximum number of export cables is six, while the maximum length of the array cable is 514km. In addition, the maximum length of the interconnector cable is 100km.

The O&M facility, i.e. the service port, is yet to be chosen.

According to Vattenfall, the project’s lease period would last up to 50 years, while the indicative construction duration would be between 3 and 7 years.

Construction of the project under either approach is anticipated to commence between 2020 and 2021 for the onshore works and around 2022 for the offshore works.

The Swedish company launched the Norfolk Vanguard project in March 2016, and is planning to submit a planning application to the UK Planning Inspectorate in 2018, with hope to obtain an irrevocable consent in early 2020.

Keen on Project Flexibility and Next-Generation Solutions

Vattenfall announced that the detailed design work for the project will occur post-consent following financial close and procurement of contractors, materials and infrastructure.

The company said that the project design envelope must provide sufficient flexibility to enable Norfolk Vanguard Ltd. and its contractors to use the most up to date, efficient and cost effective methods and technology in order to enable the commercial success of the project. In addition, post-consent/pre-construction site investigation will further inform the detailed design.

Schematic illustrating the maximum turbine dimensions. Source: Vattenfall

Key aspects where Vattenfall eyes flexibility include wind turbines, HVAC/HVDC connection, build-out, and construction and maintenance methodologies.

The flexibility is required for turbine capacity and parameters due to the potential evolution of technology prior to construction of the wind farm.

Additionally, flexibility regarding built-out scenarios/phasing options is necessary so Norfolk Vanguard Ltd. is able to construct the offshore wind farm so it produces power to the National Grid as early as possible while maximising efficiencies during construction, and construction and maintenance methodologies should enable competitive procurement and the most cost effective option to be adopted.

Norfolk Vanguard Ltd. is considering both a HVDC and a HVAC electrical solution for the offshore and onshore infrastructure for the project. A decision on the final electrical solution for the project would be made post-consent during the final design stage of the project and it would be based on the best available technology, balanced with providing the best value for electricity consumers.