Powering over one million British households with green electricity


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All 174 wind turbines have now been installed at the world's largest offshore wind farm Hornsea 1. When operational, Hornsea 1 will be almost twice the size of the world’s largest wind farm to date – the Walney Extension - and capable of powering well over one million UK homes with renewable electricity.

Located off the Yorkshire coast, Hornsea 1 will span an area of approximately 407 square kilometres, an amount that is equivalent to five times the size of the British city of Hull. Consisting of 174 7-megawatt (MW) wind turbines with an individual height of 190 metres above sea level and three 75m long blades, each turbine will be able to power a UK home for over a day with each single rotation.

With the bulk of the turbines’ blades constructed at Siemens Gamesa Renewable Energy’s factory in Hull, the turbines’ components were subsequently transported 120km to the Hornsea 1 site. Transportation of the wind turbines required two specialist installation vessels which jack up in the sea to provide a sturdy base for lifting.

Four turbines were loaded on to the vessel each time. The main components are a steel tower, three turbine blades and a nacelle, which houses all generation components for the turbine. On average, it takes around 12 hours of precision working to install a turbine in full.

Part of an impressive array dotted over an area spanning 407 km2 in the North Sea, the Hornsea 1 windfarm is situated more than 100km from the Yorkshire coast.

Now the final turbine is installed, the project will undergo a period of commissioning, and will be officially inaugurated in 2020 as the world’s largest offshore wind farm.

First wind farm to cross 1GW capacity
The electricity generated by the turbines will pass via undersea cables through one of three massive offshore substations, and the world’s first offshore reactive compensation station, all fully installed, before reaching shore at Horseshoe Point, Lincolnshire. The electricity is then transported via underground cables to the onshore substation in North Killingholme, where it connects to the UK National Grid.

Once complete, the site will be the world’s first offshore wind farm to be able to generate over 1GW of green electricity – enough to power well over one million UK homes.

Duncan Clark, Ørsted Programme Director for Hornsea 1 said: “The milestone of this last turbine being installed only nine months after the first one was erected is just one small part of this record-breaking project. Hornsea 1 has truly paved the way for the next generation of offshore wind farms. At the time of taking on the project, its scale and the technical pioneering required seemed a Herculean challenge, but a truly extraordinary effort from all those involved have managed to make this impressive feat of engineering the new norm.”

8,000 people
Construction of the world’s largest offshore wind farm commenced in January 2018, when the first monopile foundation was installed by GeoSea’s installation vessel, Innovation. Completing construction and installation has involved a host of contractors, suppliers and Ørsted employees, with over 8,000 people having been inducted to work offshore at Hornsea 1’s site.

Due to the distance from shore, the offshore construction team based themselves on site, 120km out to sea, to help ensure the project adhered to both safety procedures and schedule – no mean feat in dynamic weather conditions.

Living on board the GMS Endeavour for two weeks at a time, employees were able to stay close to the action, as well as enjoy a gym, on-site catering, laundry service and high-speed internet.

The United Kingdom is the first major economy to enact legislation requiring the country to reach net zero greenhouse gas emissions by 2050. Hornsea 1 will not only assist the United Kingdom in meeting its carbon reduction targets, but also safeguards local employment, thereby attaining green growth, which is a central plank of the country’s Industrial Strategy.

Facts about Hornsea 1

  • Hornsea 1 is the world’s biggest offshore wind farm with a capacity of 1.2GW, nearly double the current world’s largest offshore wind farm, Walney Extension.
  • The wind farm comprises 174 Siemens Gamesa 7MW turbines (190m from sea level with 75m long blades) and will be capable of powering well over one million UK homes.
  • At 120km from shore, it is the furthest from shore an offshore wind farm has ever been built.
  • Hornsea 1 features the longest ever AC offshore wind export cable with a total length of 467 km.
  • Three 400MW offshore substations will convert to high voltage the clean electricity from the medium voltage cables connected to each wind turbine.
  • Hornsea 1, which will cover an area of 407 square km, is 50/50 joint venture between Ørsted A/S and Global Infrastructure Partners (GIP).

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