Offshore wind energy in France: wind turbines of Alstom

Alstom inaugurated the largest offshore wind turbine in the world, at Carnet in the Loire-Atlantique. The ceremony was attended by Eric Besson, Minister of Industry, Energy and the Digital Economy, and Patrick Kron, Chairman and CEO of Alstom.

The 6MW Haliade 150 wind turbine has been developed in response to a call for tenders launched by the French government in July 2011 that aims to install 3 GW of wind turbine power off French shores by 2015. In preparation for its certification, the first Haliade 150 will undergo a series of year-long tests on land at the Carnet site, before a second turbine is placed in the sea off the Belgian coast in autumn 2012. Pre-series production is planned for 2013 with production in series due to start in 2014.

The Carnet site, located near Saint-Nazaire on the shores of the estuary, was chosen for its geological characteristics that are very similar to the submarine environment in which the wind turbines will eventually be installed. The 25 metre sub-structure (known as the jacket) was installed on pillars driven more than 30 metres into the ground on which the 75 metre high tower was then gradually mounted. The nacelle soars over the landscape 100 metres above the ground. The wind turbine and its support structure have a total combined weight of 1,500 tonnes.

Alstom is the exclusive supplier to the consortium led by EDF Energies Nouvelles which includes Dong Energy, the Danish energy specialist and world leader in offshore wind farms, as well as the developers Nass & Wind and wpd Offshore. The consortium’s agreement with Alstom offers a unique opportunity to develop a wind turbine based on French technology, built and assembled in France, employing a substantial number of local industrial contractors and benefiting from technological partnerships with various bodies. This project will involve nearly 200 suppliers to the offshore wind turbine sector.

If the consortium’s response to the tender is successful, Alstom plans to establish up to 4 factories to produce components for these offshore wind turbines and for their assembly, in the port areas of Saint-Nazaire (Loire-Atlantique) for the nacelles and alternators, and in Cherbourg (Manche) for the blades and towers. These French sites will be the first Alstom sites in the world entirely dedicated to offshore wind power and will permit the creation of 5,000 permanent qualified jobs, including 1,000 direct jobs.

Each of these next generation offshore wind turbines will be able to supply the equivalent of the electricity consumption of 5,000 households.

To meet the severe challenges posed by the marine environment, Alstom has developed a 6 MW wind turbine which is simple, robust and efficient, to improve the competitiveness of offshore wind power. Simple, this wind turbine will function without a gear box (by direct drive) and is fitted with a permanent magnet generator, to reduce operating and maintenance costs. Robust, the Haliade 150 is fitted with Alstom PURE TORQUER technology which protects the generator by diverting unwanted stresses from the wind safely to the turbine’s tower, thereby optimizing performance. Lastly, the Haliade 150 offers more efficiency with its 150 m rotor (the 73.50 m blades are the longest in the world) ensuring an improved load factor.

To date, Alstom has built or installed about 2,300 wind turbines that generate more than 3,000 megawatts, in a dozen countries (Spain, Brazil, United Kingdom, France, Italy, Portugal, Morocco, United States…). Alstom engineering innovations have made it possible to increase the size and power rating of these wind turbines. Alstom’s onshore turbines have ratings of between 1.7 and 3 MW.

Onshore tests allow easier access to the turbine to carry out the numerous measurements and manipulations required for the certification of the first unit, a procedure which necessitates the installation of a measurement tower close by.

The electrical equipment installed in the tower (converters, transformers, low-voltage electricity network, computer networks and calculators) will undergo advanced validation tests.

The generator will be subjected to tests which measure operating temperature, vibrations, current and voltage.

Then, the turbine’s different mechanical components will be tested for vibrations, stresses (notably for the blades) and reaction times.

Lastly, the turbine’s global performance and piloting software parameters will be analyzed during this onshore test phase.

Offshore wind power testing will begin in autumn 2012, permitting testing of aspects of maintenance and connection under real operating conditions.