EXTENDED ROTOR TURBINE - PHASE2

Well over 50 % of US land area constitutes low wind-speed sites, yet current wind turbines are not effective in low winds. To extract significantly more energy from such DOE Class 1 or Class 2 wind sites requires substantially increasing turbine blade rotor diameter (wind power is proportional to the square of the blade diameter).Recently, we have successfully demonstrated advanced low-RPM generators for small wind turbines that can be utilized with significantly extended length blades to economically produce power in currently un-served low to moderate windspeed sites, and to significantly lower generation costs and increase energy production in higher windspeed sites as well. However, for such oversized blade rotors, adequate and efficient overspeed control (which is a critically important turbine function), is both more difficult and more important than usual, and there are currently no durable cost effective means of doing this.To address this problem, we propose to further investigate an innovative overspeed-resistant blade design and construct and test a demonstration turbine with significantly extended length blades utilizing a novel 2-stage overspeed control method that is robust and inexpensive, and that is facilitated by the new blade design. The overall project goal is to develop a horizontal axis wind turbine (HAWT) to:1. Cost-effectively operate within low to moderate windspeed sites where other wind turbines are impractical,2. Provide substantially shorter payback periods within higher windspeed sites as well,3. Operate more quietly as a result of the lower RPM (turbine noise is proportional to the fifth power of the blade tip speed),4. Provide less variable power generation from the daily and seasonal wind speed variations.