Offshore wind: supply chain swelling under weight of Hornsea One giant

Teesside heavy engineering companies are the latest to win contracts for supplying DONG Energy's massive 1.2GW Hornsea One offshore windfarm in the North Sea. Wilton Engineering Services will provide fit-out of 20 large transition pieces, which seat turbine pylons on top of in-situ foundations. This follows award of a further multi-million pound manufacturing contract for 56 transition pieces to another Teesside company, Offshore Structures Britain.

Hornsea One is claimed as the world's largest offshore windfarm development and is the first of a generation of projects rated at 1-2GW due to be built in UK waters. Its array of 174 turbines, each with a capacity of 7MW and standing 190m high, will produce enough electricity to power over one million homes, according to DONG Energy.

The site, 120km to the east of Grimsby, was awarded development consent in December 2014 with a strike price set at £140/MWh. Denmark's DONG Energy took full control of the project after acquiring a remaining 66.7% stake in the development early in 2015. Since then the company has awarded contracts to Atkins for design of three offshore substaions, to Ramboll and Babcock respectively for design and construction of a reactive compensation substation part way between the site and shore.

Balfour Beatty is building the project's main onshore substation at North Killingholme in North Lincolnshire, through a £25m contract, while Siemens is supplying the Hornsea One turbines from its purpose-built factory at Greenport Hull. DONG Energy has estimated it will spend over £6bn through the Humber region in the course of constructing Hornsea One. Commissioning of the site is due in 2020.

Not all of the project's £6bn plus cost will pass through the UK supply chain. Wilton Engineering will fit-out transition pieces for the German supplier Steelwind Nordenham. Likewise, Offshore Structures holds a subcontract with main supplier Bladt Industries of Denmark.

The offshore wind market undoubtedly promises a long term boost for UK infrastructure and manufacturing, however. The market has an estimated project pipeline worth an estimated £21bn up to 2020, according to UK Trade & Investment. Over the longer term, DONG Energy is also the majority stakeholder in Hornsea Two and Three, which will have a combined rating over over 3GW.

Announcing the latest contract awards, DONG Energy's Hornsea One project director, Duncan Clark, said: "We are delighted to be working with Steelwind again and it's great to see UK firms like Wilton Engineering build their capabilities to supply the offshore wind industry.

"Hornsea One will be the biggest windfarm in the world and will benefit all of the UK with over 1GW of green electricity. As we work with more UK firms on these multi-million pound contracts we're really seeing the regional benefits too, such as job creation and economic growth.  For these firms, this could be the start of a lucrative journey as the offshore wind industry is growing very quickly. The growth is not limited to the UK, so as well as supporting projects here, firms that are able to demonstrate their ability could potentially look forward to export opportunities too."