Developing the world’s largest offshore wind farm
Greater Gabbard will be the world’s largest offshore wind farm. Located in the North Sea, off the Suffolk Coast, 140 turbines are expected to produce 504MW of power – enough to power 415,000 homes.
Dr Mark Hutchinson, Director at engineering consultancy Ramboll and a member of the Institution, has been working on the Greater Gabbard project.
Designing the wind farm at Greater Gabbard
Mark and his team are responsible for the foundation design of the wind farm and have been working to solve a number of engineering challenges.
Each turbine at Greater Gabbard will be 79.5m high with a rotor diameter of 107m and at the location the water depth varies between 22.4 and 31.7m.
This means that the foundation design has to take into account how 140 large structures are safely secured to the ocean bed, the stresses on the entire turbine structure including the rotor and tower during construction and operation, and the response to environmental conditions, including simultaneous wind and wave or current action.
The design life of the turbines is 25 years, so Mark’s team have carried out a series of rigorous tests to ensure the wind farm design takes account of extreme events, daily stresses, fatigue, corrosion, ship impact and serviceability for turbines located 23km off land.
Constructing the wind farm
The tests have now been completed and the onshore infrastructure build started in July 2008 at Sizewell. Subsea cables landing at Sizewell will export the power generated. Underground onshore cables will connect these subsea cables to a new sub-station to be built near the existing Sizewell nuclear power station, the sub-station will then connect to existing overhead lines.
Offshore wind farms and renewable energy targets
Mark believes that engineers will continue to play a pivotal role in enabling the UK to meet the renewable targets for 2020.
"To date there have been two calls for bids to develop UK offshore wind sites which are know as Round 1 and Round 2. Covering 28 locations the design phase for these schemes is coming to an end and the focus of the engineering community is switching to the recently announced Round 3 sites. These will bring whole new challenges with the possibility of 200m+ diameter turbines and 10MW+ single installations at sites with an ocean depth greater than 40 metres.
“Government has set tough targets for renewable energy, and if we are going to develop these large offshore wind farms and generate more of our energy from wind the industry will depend on the skills of the engineering community.”
In more depth
Video: Harnessing off-shore wind (BBC)