Denmark Construction work on what will become Denmark’s largest offshore wind farm, Horns Rev 3, is now under way. Vattenfall has started building a total of 49 foundations in the North Sea.

For the first time in five years a new wind farm is being built in Denmark, and it is just the first of three new Danish offshore wind farms which Vattenfall will be building in the next few years. These wind farms will boost the total Danish wind turbine capacity by almost 1,400 MW and ensure that even more Danes will get sustainable energy from their power sockets. When Horns Rev 3 is completed, it will be able to cover the annual consumption of 425,000 Danish households.

”Horns Rev 3 is the first of three offshore wind farms that Vattenfall is building in Denmark in the next few years. These wind farms will contribute greatly to our strategy of achieving fossil-free energy production within a generation,” says Gunnar Groebler, Head of Vattenfall’s wind business.

The special vessel Innovation took the first four monopiles to the Horns Rev 3 site from a Dutch port and has now arrived in Esbjerg to collect the next four piles.

The first four foundations were recently loaded aboard the special vessel ‘Innovation’ in Holland and driven into the bed of the North Sea. It is now the turn of the next four, which are loaded in the port of Esbjerg in mid-October.

”The foundations are the first visible sign that the work on Denmark’s largest offshore wind farm has begun. Horns Rev 3 is not only a milestone for Vattenfall, it also makes an important contribution to Denmark’s green transition and the related activities in the port of Esbjerg over the next few years,” says Michael Simmelsgaard, Country Manager for Vattenfall in Denmark.

Simmelsgaard points out that the foundations play a crucial role. They are designed to exactly suit the conditions on the seabed, and constant efforts are made to reduce costs so that the wind farms are less expensive.

Each foundation consists of a 40-50 metre steel monopile with a diameter of 6.5 metres. The pile is driven about 30 metres down into the seabed and will support an 8.3 MW wind turbine from MHI Vestas, currently one of the world’s most powerful wind turbines.

Site development with consideration for the marine environment
Before construction began, the seabed was prepared for the project with a geological survey followed by the blasting of three old sea mines from both world wars. In order to protect the marine mammals in the area from the noise inevitably produced when the monopiles are driven into the seabed, a support vessel will place an air-bubble system on the seabed around the construction site. The system creates a double curtain of air bubbles that attenuate the noise from the work on the foundations.

The construction work is taking place on an 88 km2 area of sea at least 34 km from the Danish west coast. The wind turbines and foundations for Horns Rev 3, which is planned to go into full operation in 2020, are being built in Denmark, Germany and Great Britain.

In addition to Horns Rev 3, Vattenfall will also build the wind farms of Kriegers Flak in the Danish part of the Baltic Sea and Vesterhav South and North wind farms off the Danish west coast in the next few years.

Facts about Horns Rev 3:

  • The foundations consist of a 40-50 metre long steel monopile with a diameter of 6.5 metres. Each weighs up to 610 tonnes.
  • The 8.3 MW turbines are manufactured by MHI Vestas and are currently one of the world's most powerful turbine.
  • The wind farm will consist of 49 turbines, sufficient to satisfy the annual power consumption of some 425,000 Danish households.
  • The turbines are 187 metres high with a rotor diameter of 164 metres.
  • Vattenfall won the tender for the construction of Horns Rev 3 in 2015.
  • The wind farm will have total output of 406 MW.

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