Wind turbines are growing up. On land and at sea, they’re getting bigger with longer blades stretching out into the air. But they aren’t doing so without some growing pains. Sure, some people pick on them for being ugly and, but the biggest factors limiting their physical growth could be price and efficiency.
last April found that if wind turbines were going to reach new heights without steep price tags, they’d need to be made differently from their more petite predecessors.
General Electric aims to do just that. With a $3-million grant from the Energy Department, the company is developing a 15-megawatt, gearless wind turbine. The direct-drive turbine wouldn’t be the first on the block (Seimens has two) or even in the family (GE has a 4-megawatt sibling), but it would be the first to re-purpose GE’s magnetic resonance technology.
Gearboxes transfer the mechanical energy of the spinning blades to the turbine’s generator, which converts it to electric power. The slow turning blades spin a rotor shaft within the gearbox, speeding up gear rotations to make the generator’s job easier. So why do without them? With a lot of moving parts, gearboxes are heavy and require a lot of maintenance, not an endearing quality for tall turbines sometimes miles out at sea.
Enter the magnets. Instead of gearboxes, direct-drive turbines use permanent magnets. For its turbine, GE is crossing over into its health care departments, designing the new turbine's generator with its MRI technology. This, they say, will increase the turbine's efficiency while cutting its weight and maintenance needs. While pricey, the superconducting electromagnets would be better off in bigger turbines, where they would contribute to more power generation. An added bonus, these magnets require smaller amounts of rare earth elements than do permanent magnets. Still in the first phase of the two-year project, the company hasn't figured everything out yet.
Ruben Fair, GE's principal researcher on the project, writes in a GE blog:
Putting a superconducting generator operating at 4.2Kelvin (-269oC or -452oF) on top of a turbine tower in the middle of some ocean is no mean feat and just the thought of it tends to give wind farm operators the shudders! So not only have we got to contend with solving all the technical issues, but we will have an uphill struggle to convince the conservative (and rightly so) wind power market that our technology is the way to go if we want to have lower electricity costs and a greener future. The complete generator including the cryogenic cooling equipment and associated ancillary equipment will have to be ruggedized to withstand the harsh marine environment.
Once they straighten out the generator, they'll need to outfit the turbine with bigger blades—that is, longer and stronger but not heavier blades. GE's lists lightweight composite materials in their blade plan, but perhaps they could give Marcio Loos at Case Western Reserve University a call. His research team has built the world’s first polyurethane blade that is reinforced with carbon nanotubes. At 29 inches, the prototype is tiny but mighty, reportedly eight times tougher than typical blade materials.
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Images: GE, Flickr/Adrian S. Jones
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