The wind in our sails: installation of an offshore wind farm

Published on 03 February 2022

In the Hornsea zone of the North Sea, the world’s largest offshore windfarm is being built. When all phases of the project are completed, the park will have a total capacity of 4–6 GW: the equivalent of as much as six power plants. A team from SPIE UK is helping to put the wind in its sails.

Les guides de la visite guidée du parc éolien Hornsea Project One
Mick Linford, Jonathan Hall, Simon Dixon & - SPIE UK

With the energy transition an urgent priority, wind power has huge potential. It is clean, emitting no air pollutants or greenhouse gases, and is an unlimited, renewable resource. Offshore wind is set to be the UK’s fastest-growing source of electricity in the years to come, increasing from 8% today to 33% by 2030 under government targets. This will partly be made possible by the unprecedented scale of the Hornsea offshore windfarm. Installation of its first phase, Hornsea Project One, began in 2018, and the first turbines started supplying power to the UK’s energy grid in February 2019.

Key figures

1.2 GW

green energy for one million homes


wind turbines covering 407 km2


turbines transition pieces have been installed


metre high turbines

Parc éolien Offshore Hornsea Project One

Rising to the challenge

Delivering such an installation in such a short time has involved numerous specialist contractors and suppliers around Europe. One of these is SPIE UK, which was awarded by one of its partners, the UK-based Wilton Engineering Services (WESL), a contract to install the electrical and mechanical components of 20 turbine transition pieces. 
The transition piece is part of the support structure for the turbine”, explains Simon Dixon, senior quantity surveyor at SPIE UK. “It sits on the surface of the sea on top of a monopile driven into the seabed, and the wind turbine tower is attached to it. It houses all the control and power equipment required for the turbine, with an external landing platform so engineers can access it.

Eolienne offshore

Working dockside at WESL’s site, a team of eight SPIE  engineers equipped each transition piece before it was loaded onto a barge to be carried offshore. “On the outer platform we installed illuminated signs, floodlighting, foghorns, and other warning and navigation aids”, says Jonathan Hall, the project’s electrical superintendent. “Internally, we fit the ventilation and pressure systems as well as all the cabling and electrical networks." 

Pièces de transition pour le parc éolien Hornsea Project One

The installation included complex, specialist switchboards that control the electricity generated by the turbine and the heavy subsea cables that deliver it to an offshore substation before it is brought ashore. A further challenge was that due to the scale of the project, several international fabri-cation companies were working simultaneously to build and equip the transition pieces, all of which needed to be developed in a standardised way. “It speaks volumes of the professionalism of Jonathan’s team delivering the 20 pieces to exacting standards within the deadline. Furthermore, the contract was extended to equip a 21st transition piece as a back-up should an issue arise with any other”, reveals Mick Linford, contracts manager.

Hornsea windfarm

Lying 120 km off England’s Yorkshire coast, the Hornsea wind farm breaks a number of records. A wind farm this far from shore is unprecedented. The first phase alone, Hornsea Project One, is the biggest offshore windfarm ever developed, with 174 wind turbines covering an area of 407 km². To date, more than 50 turbines are up and generating electricity, only 18 months after installation began. When Project One is fully operational in 2020, it will produce clean electricity for over one million homes.

Carte : Parc éolien de Hornsea Project One

Working together for the future

While the team has worked with WESL for over a decade building offshore modules for the oil and gas industry, this was the first renewable energy contract for both parties. This renowned project opens the door for further involve-ment in this rapidly expanding sector. SPIE UK have ten-dered for Hornsea Project Two, the second in three planned phases of the windfarm. The Hornsea project aligns per-fectly with SPIE’s commitment to using its expertise to help mitigate environmental impacts and transform urban living.  “It’s good to know that you’re part of doing something for the environment”, concludes Jonathan Hall. 

SPIE provided a high level of service, commitment and installation quality across all 21transition Pieces. As we look to further expand our business in the area of renewable energy, it is reassuring that we can look to SPIE to assist us with the electrical fit off scope in the knowledge they will provide a first-class, technically compliant installation.”
Kevin Wilson, Project Manager at Wilton Engineering Services