Greater Gabbard Offshore Wind Project, United Kingdom

The Greater Gabbard Offshore Wind Project is located 25km off the coast of Suffolk, North Sea, adjacent to two sand banks: the Inner Gabbard and The Galloper. It is situated in one of the three strategic areas identified by the UK Government for the second round of offshore wind farm development. The project is owned by equal joint venture partners Scottish and Southern Energy (SSE) and RWE npower (RWE).

The offshore wind project will have 140 wind turbines with an installed capacity of 500MW. It is the world's largest wind farm under construction and has a 40% load factor.

The Greater Gabbard project is estimated to cost £650m, excluding the cost of grid connection. It will produce 1,900kWh every year, sufficient to power 530,000 homes. It will also off-set carbon emissions of up to one million ton each year.

The project received approval from the state in October 2007. Its onshore and offshore construction began in 2008 and 2009 respectively.

The first two turbines began generating power to the national grid in January 2011. So far, all the 140 foundations have been placed and over 70 turbines have been installed in the sea. The operations base at Lowestoft has also become operational.

The first two turbines began generating power to the national grid in January 2011. So far, all the 140 foundations have been placed and over 70 turbines have been installed in the sea. The operations base at Lowestoft has also become operational.

In October 2009, a 7,000t Leviathan vessel was delivered by Seajacks to carry on the offshore project work.

Greater Gabbard will contribute 5% of the UK's 2010 renewable energy target of 10%. This target is raised to 20% by 2020 and 60% by 2050.

Contracts

The US-based Flour Corporation is carrying out the EPC contract for the Balance of Plant (BOP).

Siemens is supplying the SWT3.6 wind turbines and six 180MVA transformers. It also performed the design, grid and performance studies for the entire wind farm.

Greater Gabbard plant details

Greater Gabbard is the first wind farm to move into construction phase in the round two offshore wind farms. It spreads over an area of 147km² including the wind turbines, met masts, offshore substation platforms and other associated infrastructure.

Each turbine has a production capacity of 3.6MW and is 170m tall with a rotor diameter of 130m. They are installed on the steel monopole, which is 24-34m deep in the sea. Around 84,000t of monopiles are required for the project. Each monopile is 62m in length and weighs 600t. A 230t transition piece connects the turbine and the monopile. A total of 35,500t of transition pieces are required for the project.

A 33/132kV transformer station with three 180MVA transformers will be installed on the offshore sub-station platforms at Inner Gabbard and the Galloper.

Power to the sub-stations will be transmitted through three three-phase 132kV XLPE submarine cables, which will come onshore at Sizewell near Leiston in Suffolk.

Plant history

The project was originally developed by Greater Gabbard Offshore Winds, a joint venture of Airtricity and Flour in 2008. Subsequently, SSE acquired Airtricity and bought over 50% of the project from Fluor for £40m.

Later in November 2008, SSE sold the 50% to RWE for £308m.

The future

The new Galloper wind farm, is being developed besides the Great Gabbard farm as an extension. It is being developed under the state's extension programme by the Crown Estate to increase the existing capacity of the round one and two wind farms by 2GW.

In May 2010, SSE and RWE secured the developmental rights from the Crown Estate for 504MW Galloper wind farm. It will occupy an area of 174.9km². A planning application was expected to be submitted to the Infrastructure Planning Commission by the end of 2010. The final decision is expected in 2012.

An agreement was signed in 2009 for connection of the project with for the National Grid by SSE and RWE. The project is scheduled to commence in 2014.