Palm trees survive in very windy conditions by bending over almost 90 degrees to the ground. Their durability lies in the segmentation of their trunks. And now this feature is inspiration for another kind of very tall object: an enormous wind turbine developed by Sandia National Laboratories and several universities.
The proposed Segmented Ultralight Morphing Rotor (SUMR) is both very large—each blade could measure 620 feet—and very flexible. To cope with high wind speeds, the blades are designed to collapse and fall into the center where they're stowed against a headwind.
There's a tremendous amount of wind energy potential along the coast of the U.S. But, for cost reasons (mostly), we haven't yet managed to exploit it. It's up to ten times cheaper to generate wind power on land, which explains why the first offshore wind farm here started construction only last summer.
Engineers hope the new design could improve the economics by allowing greater generation capacity and less material outlay per kilowatt hour. By avoiding high "loading conditions," the blades need to be less robust than current blades that remain exposed to high winds. (Wind turbines are typically shut down when speeds get above 25 meters per second. Hurricanes start at about 33 meters per second).
"If we can avoid that loading condition, we can design the blades with less material at lower cost," says Todd Griffith, a wind engineer at Sandia National Laboratories, in Albuquerque, New Mexico.
Led by the University of Virginia, development is still at a relatively early stage. Griffith says the first prototype will generate about 13 megawatts of energy. If that works out, the SUMRs will be built as big as 50 megawatts, far surpassing the biggest machines today, which are 8 megawatts.
"We could also apply this to smaller turbines on land," Griffith says. "In the best case, this research will show that from 3 megawatts to 50 megawatts, this is a viable and cost effective technology."