Thanet is an operating 300MW offshore wind farm located off the south east coast of the UK. The site lies around 11.3km offshore from Foreness Point, the eastern most part of the Kent coastline, in water depths of 20m–25m.
The construction of the project commenced in January 2008 and was completed in 2010 with an estimated cost of £780m.
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At the time of commissioning, Thanet was the largest operational offshore wind farm in the world. It is capable of powering 240,000 British households annually with clean energy.
Thanet is designed to have an operational life of 40 years.
Swedish multinational power company Vattenfall owns 100% stake in the facility.
Background
Thanet Offshore Wind Limited (TOW), a subsidiary of Warwick Energy (WEL), secured the rights to develop the offshore wind farm from The Crown Estate under Round Two of the offshore wind licencing arrangements.
A hedge fund called Christofferson, Robb & Co (CRC) bought TOW in September 2007, while Warwick Energy continued to manage the project.
In November 2008, Vattenfal acquired the rights of the Thanet offshore wind farm from CRC for $55m.
Project Details
The Thanet offshore wind farm consists of 100 Vestas V90 wind turbines across an area of 35km².
Each of turbines, with a rated capacity of 3MW, stands on monopile foundations. They are installed at a gap of 500m between the rows and 800m between the columns.
The turbines have a height of up to 115m with a minimum clearance above sea level of 22m.
All the turbines are interconnected by a subsea 33kV cable network and then to an offshore substation platform where the voltage is stepped up to 132kV network.
The substation is equipped with two 180MVA power transformers to support ten 33kV import cables.
Two 132kV export cables transport the renewable electricity to the onshore substation at Richborough, near Ramsgate, from where the power is fed into the electricity grid.
The substations will also feature high-voltage and medium-voltage switchgear with the necessary protection and control technology.
Additionally, the project infrastructure includes an onshore maintenance facility to support the operations and maintenance of the wind farm.
Contractors involved
The wind turbines for Thanet were supplied by Vestas, while Ramboll was responsible for the detailed design of the wind turbine foundations. The foundation design included both primary and secondary steel design.
The turbine monopiles were from Dillinger Hütte. The monopiles feature a single hollow cylindrical pole with a diameter of up to 5m.
Dutch firms SIF and Smulders delivered the monopiles and transition pieces respectively.
Subocean was responsible for the underwater cable installations, while Noble Denton offered project management services.
In March 2008, Siemens Energy and consortium partner Prysmian Cables & Systems won an order to connect the Thanet offshore wind farm to the British power grid.
The scope of work included the construction of the offshore substation platform, delivery of two three-phase 132-kV high-voltage subsea cables to transport the electrical power to the grid connection point and a new high-voltage switching station in Richborough.
The Thanet’s offshore substation was manufactured in two separate parts, jacket and topsides. British companies McNulty and SLP supplied the jacket and topsides of the offshore substation.
The substation parts were transported to the site and installed by a heavy lift barge, the Stanislav Yudin.
The substation installation was completed by jack-up vessel Excaliber.
CCL UK was contracted to provide necessary technical expertise to ensure the project was completed on time and within budget.
In 2022, Vattenfall signed a five year corporate power purchase agreement to deliver 300,000 MWh of electricity from Thanet offshore wind farm to Shell.
Vattenfall’s wind farms in Kent
Vattenfall has three operational offshore wind farms in Kent. They are Thanet, Kentish Flats and Kentish Flats Extension.
The three farms produce renewable electricity to power around 400,000 homes in the UK annually.
Vattenfall planned to build a 340MW extension of existing Thanet Wind Farm.
However, in June 2020, the UK Secretary of State for Business, Energy, and Industrial Strategy refused to give consent to the development consent order (DCO) application for the extension, as the proposed wind farm would have impacted marine navigation.
