According to Lagerwey's Remco Boersma, the installation, although two months behind schedule, went without a hitch. "I'm convinced that the Zephyros is pretty much the ultimate wind turbine," says an ebullient Boersma. "In this class its certainly the turbine with the fewest moving parts." As one of the world's first turbines to be built specifically for offshore use, it features the greatest possible reliability and requires minimal maintenance, says Boersma. "We've reduced the service interval from twice to just once annually."
Lagerwey, based in Barneveld, is one of a six-member international project team behind the turbine. Each member has equal shares in Zephyros BV, the development company responsible for the production of the new turbine. Along with Lagerwey, which is responsible for the concept, turbine design, and sales and marketing, the consortium includes ABB, which developed the generator and converter systems, Mammoet van Seumeren, responsible for transport and installation and Dutch Polymarin, which has developed the blades. The two further members are Unitron, responsible for the control system, while the nacelle/hub assembly is by Water Wind Technology.
Alongside its expected reliability and minimal service requirements, the LW 72 boasts a number of features which its builders believe will make it more than a match for its Danish and German multi-megawatt rivals. The ABB-developed 4000 volt permanent magnet generator is the first such generator to be installed in a series production wind turbine. It ensures high efficiency on part loads, which will significantly boost annual yield, say the developers. The relatively high generator voltage and ABB converter system also save on transmission loses, claims Lagerwey.
Transport specialists Mammoet have tackled the logistical difficulties in installing the huge components of 2 MW machines. Only a limited number of 800-900 tonne cranes are available in the world, and they have to be booked months in advance leaving no leeway for poor weather conditions. Mammoet has developed a nacelle-mounted, diesel-operated, hydraulic lifting device which enables the heavier components, such as the generator and fully assembled rotor, to be lifted into position using the turbine tower's own foundations as a counterweight.
"The system worked perfectly with the prototype and will substantially reduce construction and planning costs," says Boersma. "The whole crane system packs into a container for transport from site to site. It also means that the LW 72 can be built in areas without adequate transport infrastructure, significantly boosting the market potential of the machine, believes Lagerwey.
Apart from its lack of a gear box and use of a permanent magnet generator, the Zephyros design shares a number of features with Lagerwey's successful 750 kW, LW 52 turbine, operational in various European countries and Japan. Both models share a large and simple "main axle" bearing which carries the generator rotor (the revolving component of the generator) and the whole rotor, thereby reducing the number of main components. It also enables easy access to the vital components in the rotor hub. Boersma believes the success of the LW 52 will be an important calling card for its big brother: "We have now established the reference list and the track record so people know our capability."
Seven more zero series LW 72 units are planned for the Maasvlakte this year and series production should begin at the end of the year. Lagerwey's operating company, Lagerwey Exploitatie, will probably hold a majority share in the resulting 14 MW wind farm on the Maasvlakte and the power is likely to be bought by a Dutch utility for sale as green electricity. Commercial production of the Zephyros is scheduled to begin at end 2002. Lagerwey estimates it already has buyers for some 75 of the new model for mostly onshore projects spread across Canada, Belgium, Germany, France, Japan, Spain and Brazil.