Horns Rev 3 Offshore Wind Farm

Horns Rev 3 is a 407MW offshore wind farm located in the eastern North Sea, approximately 30km off the north-west coast of Denmark.

Built with an estimated investment of £1bn ($1.3bn), the offshore wind farm is owned and operated by Swedish state-owned power company, Vattenfall.

The tender to build and operate the Horns Rev 3 wind farm was awarded to Vattenfall in April 2015.

Construction on the project was started in May 2017 and installation of all turbine foundations was completed by January 2018. The first turbine was installed in July 2018, while first power was generated in December 2018.

Fully commissioned in August 2019, the 407MW wind farm is currently the biggest offshore wind farm in the Scandinavia region.

The Horns Rev 3 wind farm  is expected to boost the Danish electricity production by 12% by producing up to 1,700GWh of clean electricity a year, which will be enough to power  425,000 Danish households.

Horns Rev 3 offshore wind farm make-up

Situated in close proximity to the existing Horns Rev 2 offshore wind farm, the Horns Rev 3 offshore wind farm includes 49 V164-8MW turbines (optimised to 8.3MW) supplied by MHI Vestas.

The wind farm occupies an optimal wind area of 88km², with the distance between turbines ranging between 1.1km and 1.5km. The water depth of the wind farm varies between 11m and 19m.

Each turbine, with 350t steel tubular tower, stands 187m-high to blade tip and weighs approximately 1,500t including its foundation.

The foundation of each turbine consists of up to 50m-long and 6.5m-diameter steel monopile coated with protective paint and installed with sacrificial anodes to prevent corrosion.

The transformer platform of the wind farm has a 1,414t jacket and a 1,766t topside.

Horns Rev 3 wind turbine details

Each turbine, with 164m rotor diameter and three 80m-long blades weighing 33t each, has a swept area of 21.12m². The turbine’s nacelle that houses generator, gearbox, and other operating equipment is 20.7m-long, 8.7m-wide, and 9.3m-high and weighs 390t.

The turbines are designed to operate at 4m/s cut-in wind speed and 25m/s cut-out wind speed and have a rated capacity of 8.3MW.

Electricity transmission from Horns Rev 3 wind farm

The electricity generated by the turbines  is transferred through 105km of array cables to the transformer platform installed with three 33/220kV transformers.

It is evacuated onshore via 34km-long 220kV export cables, before being transmitted through onshore cables to the existing substation at Endrup.

Contractors involved

MHI Vestas was contracted to provide 49 V164-8.0 MW turbines for the Horns Rev 3 wind farm, in July 2016.

GeoSea was responsible for the manufacturing, transport, and installation of turbine foundations for the project.

GeoSea used its special vessel named Flintstone for laying the scour protection for the turbine foundations.

A2SEA was awarded the contract to install turbines for the Horns Rev 3 wind farm, using its purpose-built offshore installation vessel Sea Installer, in June 2016.

Danish transmission system operator Energinet.dk was responsible for the entire transmission infrastructure of the project.

Energinet.dk awarded a contract worth $40m to ABB for the supply and installation of the alternating-current (AC) power cable system to integrate and transmit power from the offshore wind farm, in April 2014.

Prysmian was contracted to supply the onshore transmission cables for the wind farm.

VBMS was awarded the contract to install the 33kV inter-array cables between the turbines and the transformer platform for the Horns Rev 3 offshore wind farm, in June 2016.

Seaproof was subcontracted by VBMS to design and supply the cable protection systems. Bernard Controls delivered safety-critical actuators for the Horns Rev 3 high-voltage substation.

Blue Water was awarded the port logistics contract for the Horns Rev 3 wind project in September 2017.

Details of Horns Rev 1 and Horns Rev 2 wind farms

The 160MW Horns Rev 1 offshore wind farm, located in the North Sea approximately 14km west of the Danish coast, consists of 80 Vestas V80 2MW wind turbines.

Owned by Vattenfall (60%) and Ørsted (formerly Dong Energy, 40%), Horns Rev 1 has been in operation since 2002.

The 209MW Horns Rev 2 offshore wind farm, located 30km off the Danish west coast from Esbjerg, is 100% owned by Ørsted (formerly Dong Energy).

Comprising 91 SWP2.3-93 wind turbines from Siemens, Horns Rev 2 commenced operation in 2009.