Traditional upwind turbines face incoming wind. To avoid being blown into the tower, a blade must be sufficiently stiff. A lot of material is required to build these relatively thick, massive blades, which drives up their cost. Turbine blades on downwind rotors, however, face away from wind, so there’s less risk of a blade hitting the tower when wind picks up. This means that blades can be lighter and more flexible, which needs less material and therefore less money to make.These downwind blades also can bend instead of break in the face of strong winds, much like palm trees.
For six years, in conjunction with collaborators at University of Virginia, University of Texas at Dallas, ColoradoSchool of Mines and the National Renewable Energy Laboratory, Lucy Pao – the Palmer endowed chair in the department of electrical, computer and energy engineering – and her team have developed the Segmented Ultralight Morphing Rotor, or SUMR, turbine, a two-bladed, downwind rotor to test the performance of this lightweight concept.