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Flender Powers World's Largest Wind Turbine

Flender Power Transmission has supplied a gear unit and generator for the world's largest serial wind power station.

The Nordex N-80 is situated near Grevenbroich in Germany, and was officially started up by German chancellor Gerhard Schroeder. It represents the biggest and latest development in a healthy renewables industry that has seen phenomenal growth in Germany, with expenditure in this area almost doubling in the space of one year. There were over 8000 plants in Germany at the end of 1999, with a total installed power rating of 4400 MW, and the number is growing fast.

Flender is the world's largest manufacturer of gear units for wind turbines, installing one in every two around the world, from Cardiff to California.

The Nordex N-80 comprises a Flender PZAS 3415 planetary gear unit and generator. The gear unit alone weighs 18,000 kg and has a transmission ratio of 1:67.9 with a 290 litre oil tank! The Loher generator produces 2.5MW at a speed of 700 to 1300 rpm, with 690 volts. The double-fed asynchronous liquid cooled generator weighs 12,000 kg and its efficiency is more than 96% under full load.

The gear unit has four planetary gears, with a double-row self-aligning roller bearing for the main shaft, and a very compact, light and space saving footprint. The coupling between gear unit and generator is an articulated joint rubber coupling to compensate axial and radial shaft misalignment.

The wind energy plant works at full capacity with a wind speed of 14 metres per second. To start the plant, a wind speed of at least 3m/s is required – not usually a problem in an area 100 metres high – whilst the plant automatically shuts down if wind speeds exceed 25m/s for safety reasons. The wind tower is 80 metres high and weighs in at 190 tonnes. Each blade is 38.5 metres long and weighs 10 tonnes.

With its speed variability and the rotor blades featuring controllable pitch angles, the N-80 can optimally exploit different wind speeds and thereby largely compensate for fluctuations in electricity supply. A second N-80 is being installed in Denmark and series production begins later this year.

Flender UK managing director Nick Garthwaite felt the opportunities for larger capacity renewables in the UK were significant:

"If Germany can almost double its renewable energy bank in a year, we can certainly increase the contribution our own renewables are making. People are now beginning to accept that wind farms are essential if the UK is to reduce its reliance on fossil fuels long term. In another decade they will be the norm if we are to produce a quarter of our needs in this way."

A proposed EC directive is setting targets for member states, so that renewable energy sources will account for 22.1% of electricity generated in the EU by 2010.