Wind Turbine Design Reduces Blade Size, Saves Money
by Jason Lomberg, Technical Editor
Betz’ Law (culled from its namesake, Albert Betz) is a theory for flow machines. From this theory we derive the Betz Limit, that is, “the maximum possible energy...that may be derived by means of an infinitely thin rotor from a fluid flowing at a certain speed.” In windmills, this equates to how much electricity can be harvested from the wind energy. Current technology allows turbines to capture a maximum of 59 percent of the energy in wind. Massachusetts-based FloDesign can’t bypass this fundamental mechanical limit. But its new turbine could halve the costs of generating electricity from wind.
In conventional turbines, about half the wind is deflected around the blades rather than through them, resulting in a tremendous loss of efficiency (not to mention, financial drain). FloDesign’s turbines follow the jet engine model. Using a shroud to direct the air, combined with smaller blades, they’re able to speed up the electricity generation process. FloDesign claims their smaller-blade design is just as effective as the conventional larger-blade turbines. They claim the smaller blades means the turbines can be packed in closer, resulting in a net gain per acre of land. This is all in theory (FloDesign's).
FloDesign is putting its prototype through wind-tunnel testing now, and hopes to have a finished model by late 2009/early 2010.