Some Turbulence for Gear Manufacturers

MIT's Technology Review has a story that is bad news for some gear manufacturers. Two of the largest manufacturers of wind turbines--Siemens and GE--are going away from using gearboxes in their wind turbine offerings. In the face of problems associated with using gearboxes in wind turbine builds, Siemens and GE both are turning to a direct-drive system. Last month, GE announced it would invest $451.8 million in facilities to manufacture direct drive wind turbines rather than gearbox driven ones.

The new Siemens direct drive turbine is supposed to weigh 12 tons less than a gearbox-driven build due in part to developments in the build of the electromagnetic power generating portion of the turbine.

Stiesdal [the Chief Technology Officer of Siemens] says Siemens reduced weight further by inverting its generator's design. Rather than a steel rotor covered with permanent magnets spinning inside a stationary doughnut-shaped stator (the design GE is using in its four-megawatt direct-drive turbine) Siemens's rotor is a steel cylinder with permanent magnets on the inside, and this rotor spins around a column-like stator.

The company expects to have direct-drive turbines commercialized in Norway by 2012. Siemens has not experience any significant failure of its gearbox-driven turbines. The major advantage of the direct-drive turbines seems to be that they have about half as many parts as their gearbox analogues. The only significant downside to the direct-drive turbines is the relative scarcity of the rare earth metals used to make their magnets.