One of the biggest problems with typical horizontal-axis wind turbines (HAWT - pinwheel-type turbines) is that they are not very efficient at low wind speeds. This is usually dealt with by surveying sites and finding locations where wind speeds tend to be higher, so that the turbines will be more effective once they are built, but these locations are often in remote locations, far from where the power is needed.
Wind turbines that use ducts to direct the wind for greater efficiency are not an entirely new idea, but the developers of the Winga have a new approach that could make this a useful configuration for new wind turbines.
By using wings to shroud both the inlet and the outlet to the turbine, it is possible for the turbine to generate power with lower wind speeds. The Winga turbine could be located closer to the ground, so that it would be less visually obtrusive, and also makes maintenance easier to carry out. The Winga can also be configured so that it could be lowered to the ground in the event of excessive winds that had the potential to cause damage.
The Winga has a cut-in speed (where the turbine first begins to generate power) of just 2 meters per second (about 4.5 mph) wind speed and reaches full power at a wind speed of 4 meters per second (about 9 mph). A typical HAWT has a cut-in speed of 4 meters per second, and doesn't reach full power until the winds reach 10 meters per second (about 22 mph).
The compact configuration of this turbine also allows it to use an annular rotor instead of the more conventional central-axis blades, which concentrates the blade area at the edges, where the greatest amount of torque is developed. The Winga has a tower height of 35 meters (about 115 feet), and measures 36.5 meters (120 feet) in length, with a scoop opening measuring 9 meters by 12 meters (30 feet by 40 feet). All of the moving parts are contained within the enclosure, so it would not have the dynamic, moving appearance that some find bothersome with conventional turbines.
The lower height of the Winga could be a disadvantage in some respects, since faster, more consistent winds are found at higher elevations above the ground. But the ability to produce power at a lower wind speed, and the likelihood that it can produce power more consistently, could overcome that disadvantage. Steering the large scoop into the wind when the winds are swirling and less steadily coming from a single direction might also be difficult and could also lead to inefficiencies. But the possibilities offered by the Winga are interesting, and further development could be worth watching.
link: Winga E-Generator
HatTip to: @johnrobb
written by ecolife, April 02, 2012
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