The Galloper offshore windfarm is located 27km off the Suffolk Coast in the Outer Thames Estuary, UK. The project reached commercial operation in March 2018.

The offshore windfarm is the extension of the existing Greater Gabbard windfarm, which has been operational since September 2012.

Development, construction and operations is led by innogy on behalf of the project partners Siemens Financial Services, Sumitomo, ESB, and a consortium managed by Green Investment Bank and Macquarie Infrastructure and Real Assets.

The project was completed at a cost of £1.5bn ($2.31bn) and was supported with a £1.37bn ($2.08bn) debt financing from a group of 12 commercial banks and the European Investment Bank. BNP Paribas acted as the financial advisor for the project.

The project created 700 jobs during construction and provides long-term employment for 90 people during operations. Its average annual energy generation will be equivalent to the domestic needs of 380,000 average UK households.

Galloper offshore windfarm make-up

The Galloper offshore windfarm features 56 Siemens 6.3MW wind turbines with a total generation capacity of 353MW. The wind turbines rest on monopiles in a water depth between 27m and 36m.

The windfarm will have an offshore substation, an onshore substation, and 56 buried subsea array cables linking the turbines to the offshore electricity platforms. It will also include two buried subsea export cables each measuring approximately 45km. To support on-going processes, an operations and maintenance (O&M) base includes a helicopter pad and a pontoon.

Construction of the Galloper windfarm

The project was awarded development consent by the Secretary of State in June 2013.

The initial onshore ground works on the Galloper offshore wind project were completed between June and November 2014.

Construction began in November 2015. The cable works at Sizewell beach commenced in the first half of 2016. Offshore construction began in the second half of 2016, and first power is expected to be generated by July 2017.

Planning approval for the construction of the state-of-the-art Galloper O&M base to be built in Harwich was received in September 2018 and is expected to be complete by 2020.

Contractors involved with the offshore windfarm project

Renewable energy consultancy company SgurrEnergy conducted technical due diligence at the Galloper offshore windfarm to provide initial bankability feedback to the developer. SgurrEnergy also completed a detailed technical due diligence report on the project for the benefit of the lenders.

UK civil engineering company Breheny was awarded a £1m ($1.52m) contract to perform preparatory works for the onshore substation at Sizewell in June 2014.

A consortium of Alstom and Petrofac provided electrical systems for the project in September 2014.

DEME Group company GeoSea was awarded the engineering, procurement, construction and installation (EPCI) contract for the foundations in October 2015. GeoSea provided design, fabrication and installation of 56 steel monopile foundations weighing in excess of 1,100t. The foundation installation was completed by the end of 2016.

Siemens was awarded a contract to supply, install and commission 56 wind turbines for the windfarm in October 2015. The scope of contract also includes offering servicing to the wind turbines for 15 years. The installation of wind turbines was completed in 2017.

VBMS was awarded two contracts worth roughly €200m ($217.25m) in October 2015. The scope of the first contract includes installation of two 45km-long export cables, as well as route preparation, landfall operations, burial, termination and testing of the cables. The second contract includes installation of 56 inter-array cables.

In October 2015, VBMS awarded nkt cables a €53m ($57.68m) subcontract to supply buried export. The installation was completed in 2017.

JDR was awarded a £30m ($45.63m) contract to supply 56 subsea inter-array cables for the windfarm in September 2015. The cables are manufactured at JDR’s Hartlepool facility in 2016. The installation is expected to be completed by 2017.

RG Carter Southern will design and construct the O&M base, while Jackson Civil Engineering Group will construct the access roads.

Farrans Construction was selected to design, fabricate and install the pontoon for crew transfer vessels.