Gunfleet Sands 1 & 2

Gunfleet Sands 1 & 2 Offshore Wind Farm Profile

Location

The Gunfleet Sands 1 & 2 offshore wind farm is located approximately 7 kilometres southeast of Clacton-on-Sea in Essex, UK, within the Northern Thames Estuary.

Development and Ownership

• The project was developed by DONG Energy (now Ørsted), which acquired the project in 2006. Currently, the ownership is shared among Ørsted (50.1%), the Development Bank of Japan (24.95%), and JERA (24.95%).

Capacity and Turbines

• The wind farm consists of two phases: Gunfleet Sands 1 and Gunfleet Sands 2.
  • Gunfleet Sands 1: This phase has 30 Siemens Wind Power SWT-3.6-107 turbines, each with a capacity of 3.6 MW, totaling 108 MW.
  • Gunfleet Sands 2: This phase has 18 Siemens Wind Power SWT-3.6-107 turbines, each with a capacity of 3.6 MW, totaling 64 MW.
• The total installed capacity of the wind farm is 172 MW.

Construction and Operational History

• Construction began in the spring of 2008 and was completed by June 2010. The first turbines were installed in April 2009, and the wind farm transmitted its first green power to shore in August 2009. Full production was achieved in the spring of 2010.
• The wind farm was officially inaugurated in June 2010.

Technical Details

• Turbine Installation: The turbines are installed on monopile foundations with a diameter of 5 meters, overall lengths of up to 75 meters, and a seabed penetration depth of up to 50 meters.
• Foundation and Cabling: The monopoles were laid using the offshore vessel Excalibur owned by Fugro Seacore. The turbines were erected by the offshore vessel Sea Worker owned by A2SEA. The inter-array and export cables were supplied by JDR Cables.
• Power Transmission: The electricity is collected by an offshore substation and transmitted to the shore at Holland on Sea via underwater power cables. The voltage is stepped up to 132 kV for the local grid.

Environmental and Operational Impact

• The wind farm generates approximately 570,000 MWh of electricity annually, sufficient to power around 125,000 households. It offsets about 480,000 tons of carbon dioxide emissions per year.
• During the St Jude storm in October 2013, wind speeds of up to 65 meters per second (150 mph) were measured at the site.

Financial and Regulatory Aspects

• In September 2011, Marubeni Corporation acquired a 49.9% shareholding of the farm for £200 million. Later, Marubeni divested part of its stake to the Development Bank of Japan.
• The transmission assets were divested to TC Gunfleet Sands OFTO Limited in July 2011 due to regulatory changes.

Performance Metrics

• The wind farm has a capacity factor of 31-35% (as recorded in 2011/12) and a levelised cost of £122 per MWh.
• The average wind speed at the site is 8.8 m/s (29 ft/s) at a height of 60 meters.