Middelgrunden, Denmark [Image source: Kim Hansen, Flickr]
Middelgrunden is situated in the Øresund, 3.5 kilometers from Copenhagen. The offshore wind farm was completed in 2000 when it was the world’s largest, with 20 turbines and a 40 MW capacity. It supplies around 4 percent of the power for Copenhagen. The project was initiated by the Copenhagen Environment and Energy Office (CEEO) and listed in the Danish Action Plan for Offshore Wind. Local people also formed the Middelgrunden Wind Turbine Cooperative which cooperated with Copenhagen Energy. Each turbine stands on concrete gravity base foundations which were considered to be the cheapest option. The wind farm is clearly visible from Copenhagen.
Barrow is a 90 MW offshore wind farm developed by DONG Energy and Centrica located in the East Irish Sea approximately 7 kilometers south west of Walney Island, near Barrow-in-Furness. It consists of 30 Vestas 3 MW wind turbines and covers an area of approximately 10 square kilometers. It generates around 305 gigawatt hours (GW/h) of energy, which is enough to supply around 60,000 British households. The electricity generated by the wind farm is delivered to the National Grid by a substation at Heysham, Lancashire, via 27 kilometers of subsea and onshore transmission cables. The wind farm was commissioned in 2006 with the first power being generated by the wind farm in March of that year. It is operated by DONG Energy technicians from an operations and maintenance base in Barrow-in-Furness.
Gwynt y Môr
Gwynt y Môr is the flagship project of RWE Innogy and is currently the second largest operating offshore wind farm in the world. The site consists of 160 wind turbines in Liverpool Bay, off the coast of North Wales. It was funded by RWE Innogy in partnership with Stadtwerke München GmbH, and Siemens AG and has an operational installed capacity of 576 MW, incorporating Siemens 3.6 MW turbines and generators. It can generate enough energy for the average annual needs of 400,000 homes. Gwynt y Môr was officially inaugurated on 18th June 2015.
The London Array
London Array was developed by a consortium of three leading global renewable energy companies: E.ON, DONG Energy and Masdar, as well as La Caisse de dépôt et placement du Québec (Caisse), a global investment company and one of the largest institutional fund managers in Canada and North America. E.ON has a 30 percent stake in the project, DONG Energy and La Caisse de dépôt et placement du Québec (Caisse) 25 percent each and Masdar 20 percent. The site is more than 20 kilometers off the coast of North Foreland in Kent, in the area of Long Sand and Kentish Knock, between Margate in Kent and Clacton in Essex. The first phase of the project consists of 175 Siemens wind power SWT-3.6 wind turbines and two offshore substations which gave the offshore wind farm a peak rated power of 630 MW. Each turbine stands on a monopile foundation and the turbines are connected by 210 kilometers of 33 kilovolt array cables. A substation at Cleve Hill, near Graveney on the North Kent coast, is connected to two offshore substations by four 150 kilovolt subsea export cables. To the south of the London Array is the smaller Thanet Wind Farm.
The 500 MW Greater Gabbard offshore wind farm stands on sandbanks 23 kilometers off the Suffolk coast and was officially opened on 7th August 2013 by Michael Fallon MP, Energy Minister. An investment of £1.6 billion resulted in a project consisting of 140 SWT3.6-107 wind turbines capable of providing enough renewable energy to supply around 530,000 homes per year. The wind farm was completed in 2012. Electricity generated by the facility is brought ashore by three 45 kilometer export cables and operations and maintenance is conducted from a £1.5 million base in Lowestoft. The project was developed by Greater Gabbard Offshore Winds Limited (GGOWL), a joint venture between Airtricity and Fluor. Both stakes have now been bought by Scottish and Southern Electricity (SSE).
Anholt is Denmark’s largest offshore wind farm. It is located between Djursland and the island of Anholt and was constructed between 2012 and 2013 by DONG Energy. Difficult seabed conditions resulted in extra installation costs and also meant that some of the proposed wind turbine deployment locations had to be abandoned. The wind turbines were supplied by Siemens from production facilities in Brande and Aalborg. The foundations were supplied by MT Højgaard and Nexans produced the array cables connecting the turbines with the offshore transformer station.
Written by Robin Whitlock