| rdfs:comment | - Small wind turbines may be as small as a fifty watt generator for boat or caravan use. Small units often have direct drive generators, direct current output, aeroelastic blades, lifetime bearings and use a vane to point into the wind. Larger, more costly turbines generally have geared power trains, alternating current output, flaps and are actively pointed into the wind. Direct drive generators and aeroelastic blades for large wind turbines are being researched. The dominant models on the market, especially in the United States, are horizontal-axis wind turbines (HAWT).
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| abstract | - Small wind turbines may be as small as a fifty watt generator for boat or caravan use. Small units often have direct drive generators, direct current output, aeroelastic blades, lifetime bearings and use a vane to point into the wind. Larger, more costly turbines generally have geared power trains, alternating current output, flaps and are actively pointed into the wind. Direct drive generators and aeroelastic blades for large wind turbines are being researched. A small wind turbine can be installed on a roof. Installation issues then include the strength of the roof, vibration, and the turbulence caused by the roof ledge. Small-scale rooftop wind turbines have been known to be able to generate power from 10% to up to 25% of the electricity required of a regular domestic household dwelling. Smaller scale turbines for residential scale use are available, they are usually approximately 7 feet (2 m) to in diameter and produce electricity at a rate of 900 watts to 10,000 watts at their tested wind speed. Some units have been designed to be very lightweight in their construction, e.g. 16 kilograms (35 lb), allowing sensitivity to minor wind movements and a rapid response to wind gusts typically found in urban settings and easy mounting much like a television antenna. It is claimed that they are inaudible even a few feet under the turbine. Dynamic braking regulates the speed by dumping excess energy, so that the turbine continues to produce electricity even in high winds. The dynamic braking resistor may be installed inside the building to provide heat (during high winds when more heat is lost by the building, while more heat is also produced by the braking resistor). The location makes low voltage (around 12 volt) distribution practical. In the United States, residential wind turbines with outputs of 2-10 kW, typically cost between $12,000 and $55,000 installed ($6 per watt), although there are incentives and rebates available in 19 states that can reduce the purchase price for homeowners by up to 50 percent, to ($3 per watt). The US manufacturer "Southwest Windpower," estimates a turbine to pay for itself in energy savings in 5 to 10 years. The American Wind Energy Association has released several studies on the small wind turbine market in the U.S. and abroad, showing that the U.S. continues to dominate the Small Wind industry.[1] According to another organization, the World Wind Energy Association, it is difficult to assess the total number or capacity of small-scaled wind turbines, but in China alone, there are roughly 300,000 small-scale wind turbines generating electricity. The dominant models on the market, especially in the United States, are horizontal-axis wind turbines (HAWT). There have been a number of recent developments of small turbines which could be adapted to home use, including:
* Jacobs Wind International Jacobs Wind.
* The AeroTecture vertical-axis turbine
* The AeroVironment Architectural Wind Project
* The piezoelectric windmill project
* The Swift home wind turbine. The Swift project peaked in 2004 and has had some implementation difficulties while promising to be a low-noise/safe roof-mount/low-cost alternative
* The Motorwave micro-wind turbine
* The Chispito Wind Generator. This small wind turbine was designed to be easily construction from salvaged materials, including a surplus treadmill motor, sewer pipe for blades, and various scrap metal for the mount and tail.
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