Gunfleet Sands Offshore Wind Farm

Gunfleet Sands 1 & 2

Gunfleet Sands 1 & 2 are located 7 km south east of Clacton-on-Sea, Essex, UK; in water at depths of 2 to 15 m (6 ft 7 in to 49 ft 3 in) (spring tidal range ~4.6m); Gunfleet 1 consists of 30 turbines in a 5x6 array, whilst Gunfleet 2 consists of a 9x2 array of turbines directly adjacent to the southeast; the installed capacities are 108 and 64MW respectively. The average wind speed is 8.8 m/s (29 ft/s) at 60m elevation.

The offshore turbines connect to a 33kV offshore substation, which steps up the transmission voltage to 132kV; the export cable makes landfall at Holland Haven (nr. Holland-on-Sea), and underground cables connect it to the National Grid at the Cooks Green substation.

Development

Development of an offshore wind farm site near Clacton-on-Sea began in 1996 under Windmaster Developments; Windmaster was acquired by Enron in 2000, and passed to General Electric (GE Wind Energy) in 2002. A Round 1 concession for the development was awarded in 2001, and planning consents obtained in 2003/4.

In June 2006 a consent application and environmental statement was submitted to the Department of Trade and Industry for permission to build and operate an extension (Gunfleet Sands 2) to the originally consented project, including up to 22 further turbines with an additional capacity of 64MW. In December 2006 Dong Energy acquired the 100MW "Gunfleet 1" project from GE.

A contract for 30 Siemens Wind Power 3.6MW turbines was signed in April 2007.

Planning application for Gunfleet Sands 2 was submitted to the Department for Business Enterprise and Regulatory Reform in June 2007, and permission was received in 2008.

Construction

Construction began in 2008, with initial work including onshore infrastructure and cable installation. A formal groundbreaking ceremony was held in April 2008. The first turbine was installed in April 2009.

MT Højgaard was contracted to instal the monopile foundations; work started in October 2008; Sif supplied the monopiles and transition pieces, and Smulders supplied the wind turbine foundations,

The cabling was supplied by Prysmian, Bladt Industries constructed the offshore monopile substation superstructure, with electrical equipment supplied by Areva T&D and ABB Group.

Construction of the wind farm was delayed, in part due to cable laying company Oceanteam going into administration in May 2009, as well as the breakdown of liftboat KS Titan 2.

Electrical generation from the partially complete wind farm began in August 2009. The wind farm was fully operational by March 2010; the wind farm was formally opened on 15 June 2010 by Anders Eldrup (Dong Energy) and UK Energy minister Charles Hendry. Cost of the development was 4 billion Danish Kroner. Large scale development of wind farms in the UK was made possible by generous subsidies - in 2010 wind farms were receiving 1.20 Danish Kroner per kWh, compared to approximately 0.50 Kroner (Horns Rev 2) in Denmark.

An operations and service center was built in Brightlingsea on the site of a former boatyard.

Operational history

The wind farm produced between 450 and 520 GWh between 2010 and 2012, with a capacity factor of 31-35% (2011/12).

The electrical transmission assets of the wind farm were divested in July 2011 to TC Gunfleet Sands OFTO Limited in response to changes in governmental legislation. In September 2011 Marubeni Corporation acquired a 49.9% shareholding of the project for £200 million. In 2013 Marubeni divested part of its stake to the Development Bank of Japan.

During the St Jude storm of October 2013, wind speeds of 65 metres per second (150 mph) were measured at the wind farm.

Gunfleet Sands 3

A planning application for the Gunfleet Sands 3 - Demonstration Project (GFS 3) was submitted in 2010. The project consisted of a wind farm about 1 km² (0.39 sq mi) 8.5 km southeast of Clacton-on-Sea, and adjacent to the Gunfleet 1 & 2 wind farms but southeast of them. The site was intended to be provide the facility to test new wind farm equipment in preparation of the Round 3 wind farm letting process. 2 wind turbine installations were proposed.

The development required a separate export cable and grid connection to the Gunfleet 1&2 farms; a planning application for the onshore electrical facilities and cabling was submitted in November 2011. Inter array and export cables (33kV) were supplied by JDR Cables.

The monopile foundations and transition pieces were supplied by Bladt Industries and installed by Ballast Nedam in 2012. Two Siemens 6MW turbines were installed in January 2013 by A2SEA.

The site began generating power in April 2013. Damage to one of the turbines blade tips necessitated blade replacement in mid 2013. The facility was officially opened on 12 September 2013 by UK Energy Minister Greg Barker.