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Publication Number: CEC-500-2007-111
Abstract:
Increasing the power of wind turbines, by increasing rotor diameter, results in engineering challenges of excessive blade weight, excessive torque, and low rotor RPM, requiring a gearbox. By combining seven separate rotors to spin a common driveshaft, this research demonstrates a new method to increase the swept area and power production of a wind turbine, without increasing diameter. The resulting high RPM shaft rotation directly drives the generator, needing no gearbox. Six months of testing at the facilities of Windtesting.com in Tehachapi, CA confirm reliable operation. Seven 7-foot (2.1 m) diameter rotors produced 4500 watts in winds of 27 mph (12 m/s), compared to 690 watts for one rotor. Spacing between rotors, and an offset angle from the wind direction, providing fresh wind to each rotor, for 5 to 6 times the power at all wind speeds. Winds up to 45 mph (20 m/s) produced continuous full power output and smooth operation, proving a new method of over-speed protection. Results exceeded targeted output goal, achieving a best-case scenario. Therefore, a new method to multiply the power output of a wind turbine, without increasing the diameter, is demonstrated, reducing the array turbine, with its known advantages, to a single moving part. The data generated from this research provides a scientific basis of comparison using industry-standard blades, to prove that multiple rotors mounted to a common driveshaft can effectively work together to generate vastly more power than a single rotor of the same diameter, validating a promising direction in wind turbine design. Keywords: wind turbine, multi-rotor, array turbine, direct-drive generator, power, renewable energy, electricity, wind energy, offshore wind, RPS
Author(s): Selsam Innovations, Doug Selsam Commission Division: Technology Systems Division - R&D, PIER (500)
Office/Program: PIER: Public Interest Energy Research
PIER Program Area: Energy Innovations Small Grant (EISG)
Date Report Completed: December 2007
Date On Line:
04/24/2008
Acrobat PDF File Size: 55 pages,
3,300 kilobytes**
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