Barrow Offshore Wind Farm
Irish Sea 7.5km SW of Walney Island, near Barrow-in-Furness, Cumbria, UK
Vestas Wind Systems A/S
Marine Projects International
date April 2005 - June 2006
era Modern |
category Power Generation |
Barrow Offshore Wind (BOW) is a joint venture between Centrica (UK) and DONG Energy (Denmark). The wind farm it operates covers some 1,000 hectares, with four rows of wind turbines — two rows of seven and two rows of eight, making 30 turbines in all.
Construction of the wind farm was carried out under a five year Engineering Procurement Installation and Commissioning contract, awarded to Vestas-KBR (Vestas-Celtic Wind Technology Ltd and Kellogg Brown & Root Ltd) in July 2004. Vestas also supplied the turbines, which are V90s. Each has an output of 3MW, giving a 90MW capacity. The electricity produced is sold to Centrica’s subsidiary British Gas and the UK's National Grid.
The foundations for the wind farm consist of steel monopiles driven (and sometime drilled) into the seabed in 15-20m depth of water. They were designed by Marine Projects International. The four rows of monopiles are 750m apart, with the turbines at 500m centres.
Each 75m high turbine mast, which supports a turbine, is bolted onto a transition piece that caps the top of a monopile with a landing and maintenance platform. This enables the masts to be mounted vertically, even if a monopile is not vertical. The masts are in three sections — each pre-fitted with ladders, lifts, power cables and lighting.
The nacelle, hub and two rotor blades of each turbine are assembled onshore and brought to site as one unit for installation at the top of a mast. The last lift is to fit the third rotor blade on to the hub.
Mean wind speed at the turbine hub is 9m per second. The blades begin to turn at 4m per second, have full power output from 14m per second and stop operating at wind speeds over 25m per second.
The rotor diameter is 90m and each of the three rotor blades attached to the hub weighs 7 tonnes. Each wind turbine weighs between 765 and 845 tonnes, of which the mast weighs 153 tonnes and the nacelle 91 tonnes.
The wind turbines generate power at 33kV, which is transformed up to 132kV at BOW’s 480 tonne offshore sub-station. A 27km long buried subsea and onshore transmission line brings the electricity to the National Grid connection via a new sub-station at Heysham, Lancashire. The line comprises copper conductors and fibre optic cables, and was laid before the turbines were installed.
BOW produces enough power for 65-75,000 homes, and saves around 200,000 tonnes of carbon dioxide emissions annually compared with burning fossil fuels.
Monopiling was completed in November 2005, the first power was generated in March 2006 and the wind farm was completed in June 2006.
Substation electrical design: Areva
Main contractor: Vestas-KBR
Off-shore substation fit-out: Agrilek