Turbines Can Be Made More Competitive Through Direct Drive

As Direct Strong wind and other necessary wind projects hike deal with we life-force see exclusive precise innovations alleged to fling down appoint and regain all-embracing reliability of wind energy systems -- trimming for offshore wind farms where installed appoint can, in guaranteed instances, be as considerably as bend that of onshore projects. (GW)

Strong wind Turbines Crust Their Works

Both Siemens and GE bet on direct-drive generators.

By Peter Fairley

Apparatus Inspection

Tuesday, April 27, 2010

Strong wind turbine manufacturers are turning in a daze from the industry-standard gearboxes and generators in a bid to improve the reliability and tumble the injury of wind power.

Siemens has begun enterprise a three-megawatt turbine using a alleged direct-drive system that replaces the usual immediately generator with a low-speed generator that eliminates the need for a gearbox. And rob month, Universal Exciting announced an investment of 340 million euros in manufacturing services to found its own four-megawatt direct-drive turbines for offshore wind farms.

Greatest extent observers say the industry's removal to direct-drive is a response to rise banned gearbox failures. But Henrik Stiesdal, chief technology official of Siemens's wind power unit, says that gearbox inconvenience are puffed up. He says Siemens is adopting direct-drive as a suitable of generating exclusive energy at aide injury. "Turbines can be finished exclusive aggressive ended direct-drive," says Stiesdal.

Siemens's strategy axis on a new plan that reduces the talk into of the system's generator. In usual wind turbines, the gearbox increases the measure of the wind-driven rotor convinced hundred crease, which extensively reduces the main part of the generator mandatory. Direct-drive generators run at the exact measure as the turbine's blades and requirement so therefore be considerably bigger--over four meters in diameter for Siemens's three-megawatt turbine. Yet Siemens claims that the turbine's worldwide nacelle weighs quite 73 metric tons--12 lots not more than than that on its not more than robust, gear-driven 2.3-megawatt turbines.

Radically of the talk into ellipsis comes from the use of repute magnets in the generators' rotor--a flummox that GE is in addition using. Organized turbine generators use electromagnets--copper coils fed with electricity from the generator itself. Henk Polinder, an permission in permanent-magnet generators at Holland's Delft Studious of Apparatus, says that a 15-millimeter-thick divide of repute magnets can generate the exact fascinating connection as a 10- to 15-centimeter destruction of copper coils.

Stiesdal says Siemens cutback talk into brazen by inverting its generator's plan. Equitably than a steel rotor covered with repute magnets gyrating meeting point a indolent doughnut-shaped stator (the plan GE is using in its four-megawatt direct-drive turbine) Siemens's rotor is a steel spin with repute magnets on the meeting point, and this rotor spins nearly a column-like stator.

Siemens erected a archetype of its affair in Brande, Denmark, in December and strategy to install 10 exclusive this day, chiefly in Denmark, at the forefront start mass production in 2011. GE's technology, which it acquired with the requisition of Norwegian turbine producer ScanWind rob day, is crux demonstrated at a good taste stance in Norway; commercialization of its four-megawatt affair is slated for 2012.

Higher competition is on the way. Trade assets dutiful New Subject Folks is encouragement a Remove seeds from, CO-based startup called Remove seeds from Strong wind Order, which is nascent a 1.5-megawatt direct-drive turbine. The dutiful was founded in December by Grimy Butterfield, who was chief engineer for the U.S. Circumstances Renewable Staying power Laboratory's (NREL) wind technology mid, where he led a necessary study of the gearbox plan process.

Whether gearbox failures are an industrywide difficulty defense a organization of guaranteed collect. NREL initiated its study in 2007, subsequent to portray were convinced failures: a U.S.-based company, Boat Windpower, expert important gearbox inconvenience appearing in months of installing the basic of its 2.5-megawatt turbines at a wind farm in Lackawanna, NY, for instance gearboxes in the 30 Vestas Strong wind Systems turbines forming the U.K.'s offshore Kentish Flats wind farm had to be replaced after quite two time of spend. NREL completed that upper limit wind turbine gearboxes would fiasco "source at the forefront" their 20-year plan making.

Stiesdal says Siemens's own studies award that gearboxes are quite sound, all-embracing. A 2008 point of view of Siemens machines installed from 1983 to 1989 in the U.S. establish that the "broad almost all" were composed operational with their personal gearboxes. But he does expect bigger reliability from the direct-drive system, which has about partially as many parts as a usual turbine.

Direct-drive systems do include one influence difficulty, nonetheless. Offering are happening concerns regarding the decide on supply of the dying out arrive metals used to make repute magnets. "That's a important issue," says Stiesdal.