Technology tests at Gunfleet Sands T
he first phase of offshore construction at Dong En-
ergy’s Gunfleet Sands Demon- stration Project is now complete, following installa- tion of the two monopiles and transition pieces. Work on connecting the
offshore and onshore elements of the project has now also reached the halfway point. Marking an important milestone in the development of this ground breaking test site – which will see the first offshore installation of Siemens 6MW turbines any- where in the world – the Gun- fleet Sands demonstration project will enable Dong En- ergy to test a number of instal- lation and construction methods, as well as collect valuable test data from the new turbines, as the company works to lower the cost of off- shore wind. This project is the first big
step in reducing the cost of en- ergy in offshore wind. Impor- tant developments including higher electricity production from fewer turbines, installa- tion of fewer turbines and therefore using fewer inter- array cables all contribute to driving down cost and increas- ing efficiency. Benj Sykes, Dong Energy
Wind Power’s UK country manager, said: “We’ve reached a significant point in the construction of the Gun- fleet Sands demonstration project.
“Completing the installa- tion of the foundations and transition pieces means that we are now ready for the ar- rival of the two new next gen-
Dong is carrying out a series of equipment tests at its Gunfleet Sands Demonstration Project
welded together from over 60 pieces of 12m long plastic pipe, was installed in Clacton-on- Sea.
Using a specialist drilling
technique, known as horizon- tal directional drilling, a 560mm diameter hole was drilled under the sea wall out to sea. The duct was then floated out to sea from the beach, connected to the drill head by divers and “pulled- back” into position through the hole.
Later this year the offshore Offshore wind turbines
eration direct drive Siemens 6MW turbines.
“These will be the first
two turbines of their kind to be installed offshore in the world and we are very excited about the potential of this new tech- nology. Crucial tests that we will conduct during the next three years will support the wider roll out of these direct drive turbines to our pipeline of projects in the UK.” A number of new methods
have been tested during con- struction and installation at Gunfleet Sands. Surveys are being con- ducted offshore to discover if one layer of scour protection around the monopiles - instead of the standard two layers - is
Offshore Technology November/December 2012
sufficient. The results of these surveys could influence the construction methods on other Dong Energy projects. Testing of a mini remote
operated vehicle has also been carried out underwater. The vehicle will be used to simplify the cable installation, which as a result would not require divers to assist in installing the subsea cable. Finally, a new cable protec- tion system will be tested which could lead to potential reductions in cost by reducing the cable installation time and simplifying the installation process itself. Onshore, complicated
work was carried out as an 800m long flexible pipe duct,
export cable will be pulled through the duct, connecting to the onshore section of the cable and in turn providing connection to the two demon- stration turbines. Once com- pleted, all sections of the cable will have been buried under- ground and protected offshore, onshore and within the duct in the critical ‘surf zone’ under the sea defences. Now a major part of the
offshore and onshore works are completed, attention turns to the laying of the subsea ca- bles in November when the cable laying barge Discoverer will arrive on site, and to the installation of the two turbines which will arrive from Den- mark in January 2013 with first power expected to be gen- erated by spring 2013.
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