Scandinavia’s Largest Offshore Wind Farm Inaugurated

Denmark’s, Scandinavia’s and Vattenfall’s largest offshore wind farm, Horns Rev 3, was officially opened on August 22.

The 49 wind turbines located 25-40 kilometers off Denmark’s west coast in the North Sea will increase Danish power production from wind by 407MW, around 12 percent - enough to power the yearly consumption in 425,000 Danish households.

The total height of the 8.3MW MHI Vestas turbines is 187 meters and each weigh close to 1,500 tons including foundation. The steel foundations together required more than 40,000 tons of steel.

The first foundation for Horns Rev 3 was placed in the seabed in October 2017, and the first turbines began delivering electricity to consumers in December 2018. During the construction phase, the turbines were shipped from the Port of Esbjerg, but from 2024 they will be serviced from the Port of Hvide Sande, where Vattenfall will establish a new service hub.

An eight-kilometer cable between Horns Rev 2 and Horns Rev 3 allows the two offshore wind farms to supply each other with electricity if the export connection to land is disconnected. The cable was used for the first time recently when the Danish system operator, Energinet, disconnected the export cable to Horns Rev 2 for four-days of scheduled maintenance work.

Ørsted and Vattenfall, invested in the 33 kV cable that creates additional security for the two energy companies’ billion-kroner investments in the North Sea. If there is a problem with the export connection to land, this is not only critical for the supply of electricity to customers on the mainland; it is also critical for the wind turbines. Offshore wind turbines must always be supplied with electricity; otherwise there is a risk of significant damage from, for instance, humidity. The cable also enables a quick and easy start-up of the offshore wind farm once the export connection is back in service. In addition, it saves diesel fuel and operating hours for the emergency generators for both the wind turbines and the service boats.

In addition to Horns Rev 3 Vattenfall is constructing the offshore wind farms Vesterhav Syd & Nord and Kriegers Flak adding a total of more than 1.4GW wind energy capacity to the Danish energy system.

Vattenfall has more than 1,200 wind turbines. The largest wind farms are: Horns Rev 3 (Denmark, 407MW), Thanet (Great Britain, 300MW), Sandbank (Germany, 288MW) and DanTysk (Germany, 288MW). Installed capacity (MW) and production (TWh) per country (2018):
Sweden 356 / 0.9
Denmark 337 (excl. Horns Rev 3) / 0.9
Germany 588 / 2.6
The Netherlands 201 / 0.4
U.K. 1077 / 3.0