This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
This Small Business Innovation Research Phase II project seeks to prototype/validate a novel, self-regulating blade for a 3-kW Residential Wind Turbine (RWT). Successful development of this next-generation blade will eliminate major technical/economic drawbacks and reliability issues with current RWT's, and will promote widespread national and international commercial deployment of wind turbines. This project will demonstrate the following: 1) low-cost, durable, impact-resistant, mass-producible (and recyclable) blades; 2) self-regulation in high-winds and load mitigation in turbulence (allowing for reduced blade mass and cost); and 3) a simpler, more-reliable downwind turbine, for which the blades themselves protect the RWT in high winds and the cost and complexity of the tail and furling mechanism are eliminated.
The broader impact/commercial potential of this project enables the nation to meet or exceed ambitious industry projections, which state that 3% of U.S. electricity could be supplied by RWT's operated by a significant share of the 15 million households that have suitable land/wind resources. The timing for the breakthroughs being pursued by this project is ideal, as incentives similar to those offered for residential solar installations are being offered for RWTs. By substantially reducing the final market barriers of high cost and low reliability, this project will have a significant market advantage and will produce a next-generation wind-power technology that will allow individual households to make significant contributions to national energy independence and security.
(RWT). The blade extends the state-of-the-art by regulating rotor speed and power through aeroelastic Bend-Twist Coupling (BTC) that progressively feathers the blade in increasing winds. Phase II field testing shows passive regulation of rotor speed through BTC of the rotor blades alone, without the cost and complexity of a mechanical furling or pitching mechanism. Figure 1 shows rotor speed acceleration decreases and plateaus for the wind speed range of 10 m/s – 14 m/s, matching the design goal. Generally, RWT reach rated power at approximately 10 m/s. A RWT equipped with Z4 blades is able to safely produce maximum power for all wind speeds above 10 m/s, without cutting out. Since the blades regulate rotor speed and power, the generator need not be oversized to protect the system and longer blades can be employed to increase power output in low to moderate winds. BTC to feather also mitigates fatigue loads from turbulence, extending blade life. The enabling technology includes a proprietary hub mount and blade structural design that allows both rotor speed and wind bending load to contribute to blade feathering. The Z4 blade allows a simpler, more-reliable downwind RWT and reduces current market barriers of high-cost and low reliability. These benefits can be realized by applying the technology to existing RWT and can be maximized by designing a RWT that specifically integrates with the Z4 blade. Distributed wind installations reduce reliance on fossil fuels and carbon emissions and help prevent grid overload and grid-wide power outages like that in India during July 2012. Benefits enabled by Z4 blades will assist meeting the American Wind Energy Association’s goal of RWT providing 3% (50,000 MW) of U.S. electrical consumption by 2020. Field testing showed an improvement in RWT productivity time due the blade’s rotor speed regulation keeping the turbine facing the wind and eliminating time furled away from the wind. Testing also showed BTC reduces blade ultimate and fatigue loads, allowing for longer blades for a given alternator size. Longer blades increase power production in low to moderate winds. These advancements make distributed wind power installation feasible in areas with typically low winds as well as high winds that were previously considered infeasible.
