A Window on the Future of Offshore Wind Turbines

LONDON -- With over 5 GW of global installed capacity, representing about 2 percent of total installed wind power capacity according to the Global Wind Energy Council (GWEC)'s latest market report, and with a whopping 80 GW projected to be installed by 2020, the offshore wind market is picking up speed.

In this second part of our look at the latest developments in wind technology (find part one here), we look offshore where larger turbines are becoming the new normal.
For example, early in February 2013 Areva Wind began installing its latest 5 MW offshore prototype, the M5000-135, with 135-metre rotor, onshore in Germany near Bremerhaven. The evolution of the existing M5000-116 machine will see new 66 metre blades, a swept area greater by close to a third - reaching 14,326 m² - and a tower of 135 metres. The new version also has a lighter nacelle and additional improvements to condition monitoring, Areva says.
Installation is due for completion in the third quarter of 2013. The M5000 has a hybrid drivetrain and is being tested offshore at the Alpha Ventus site off the North Sea coast of Germany. Each nacelle is also tested on a full-load platform before dispatch.

Serial manufacturing of the M5000-135 is expected in the second half of 2014 and the company expects to have more than 120 machines installed in the North Sea by the end of the year.
In November 2012 Areva signed a memorandum of understanding with Scottish Enterprise to develop a site for the manufacture of its 5 MW turbines in East Scotland as part of a strategy to establish three main industrial hubs, the other two being at Bremerhaven and Le Havre in France.
Meanwhile the first of the company's Haliade 150 machines installed at the Le Carnet site in the Pays de la Loire region of France has begun final testing before certification. It now operates at its nominal power of 6 MW. The second pre-commercial wind turbine, which was completed in the temporary workshop at Saint-Nazaire, is due to be installed at the Belwind wind farm. Alstom and the Belgian developer had previously signed a cooperation agreement to install one Haliade 150 wind turbine at the project near Ostend, some 45 km off the Belgian coast. Offshore tests conducted here will target specific marine operations and procedures and will complete the technical and product performance. Alstom Wind Offshore VP Frederic Hendrick said the company is particularly satisfied with the results of tests on its Pure Torque rotor support technology concerning the stability of the generator's air gap. The tests confirm Alstom's decision to develop a turbine with no gearbox, he says.
The company is expected to deliver 240 Haliade 150 units for the Courseulles-sur-Mer, Fécamp and Saint-Nazaire wind farms in France starting in 2016.
Alstom is also a member of a team led by Dominion Virginia Power, which has been awarded a US$4 million grant by the U.S. Department of Energy to complete the engineering, site evaluation and planning phase for an offshore wind demonstration project in the state of Virginia. The DOE's advanced technology demonstration programme aims to achieve large cost reductions over existing offshore wind technologies, and could see the U.S.'s first offshore wind projects enter commercial operation by 2017.
Dominion's proposal includes the installation of two Haliade 150 turbines about 35 km off the coast of Virginia Beach.

Gamesa's new 5.5 MW machine, which it says is suitable for both onshore and offshore use, will become available from the fourth quarter of 2014. The prototype turbine in this family, the G128-5 MW, features a rotor diameter of 128 metres and is based on the company's 4.5 MW machine. Design certification for its offshore machine is coming from Det Norske Veritas and is based on a prototype being installed in Arinaga Quay on the island of Gran Canaria. The first commercial machines are expected to be erected in 2014.
In addition to its 5.5 MW offshore system, the company says it foresees 7 MW–8 MW offshore turbines in the medium to long term.
And currently alone in the 8 MW class comes Vestas. Mid- December 2012 saw the company agree with DONG Energy on the testing of the new V164-8.0 MW offshore machine at Test Centre Østerild in Denmark. Under the terms of the deal DONG will help accelerate development of the turbine but will not now build one, as previously planned, as a test and demonstration project. The reason given is that access to the test bed and data at Østerild makes a second machine redundant.
Vestas expects the first turbine to be commissioned in Q2 2014. Major components of the first prototypes are nearing completion in Aarhus, Denmark and the Isle of Wight, UK, where the 80 metre blades are being manufactured. The first blade will be tested this year, while the prototype hub has been cast and is ready for testing.
Meanwhile a complete drivetrain test bed for the V164 was commissioned in early 2013 in Aarhus, and the generator and gearbox are due to be testing-ready. The new machine, which has a rotor diameter of 164 metres, initially launched at 7 MW but was bumped up to 8 MW in October 2012. Vestas said that from the beginning the platform was developed with the potential to increase the turbine size.
The world's leading offshore player, Siemens, has also revealed a new machine, as well as progress on testing its 6 MW platform. February saw the company launch its offshore SWT 4.0-130, the next generation of its 3.6 MW platform. This 4 MW machine features a rotor diameter of 130 metres. Newly designated the G4 platform, it has a conventional geared drivetrain. The new B63 rotor blade measures 63 metres. Power output is increased by up to 15 percent over the previous model. The 4 MW prototype was installed in December last year at Østerild, and serial production is expected to begin in 2015.

Alongside its two G platforms, those featuring gearless technology are identified by the prefix D, for direct drive. The latest is the offshore 6 MW unit, which began onshore testing at Østerild in October 2012. It features a new 154 metre diameter rotor and 75 metre blades. Its nacelle weighs 200 tonnes. The first prototype using the 120 metre rotor was installed at the Høvsore test site in Denmark back in 2011.
And Samsung Heavy Industries has received permission to build a 7 MW offshore turbine at a site near Edinburgh, Scotland. The permit allows for the construction of a single turbine which can be as tall as 196 metres, accompanied by offshore cabling and a bridge to the tower. The company can place one turbine on-site at any time, and can operate the machine for up to five years.
The growing number of offshore test facilities and the numerous early onshore versions of large offshore machines in preliminary testing says we're likely to see a surge of new offshore machines appearing in situ within the next year or so – and, as these turbines rack up operating hours and shake out any problems they might have, investor confidence in them will continue to grow.

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