Silent windmills are a new step forward in harnessing wind power, which will join nuclear and solar power in providing clean, renewable energy to the world's industries, offices, and homes. It is very unlikely that wind will ever be a primary source of power for our civilization - the wattage it provides is quite frail in comparison to even the smallest nuclear or fossil fuel plants. However, it is useful for niche applications, and creates no pollution.
There are various types of silent windmills, both large and small, which have been proposed for manufacture. Currently, the only type of silent windmill under mass production is called QR5, sold by the UK company Quiet Revolution. It costs about £25,000 (about 50,000 US dollars USD), with an installation cost of £5,000-£6,000 (10,000-12,000 USD). The company claims that the windmill pays for itself after about 15 years of operation, depending on wind speeds.
The QR5 is a small windmill, 5m (15ft) tall and 3.1m (10ft) in diameter. Rather than using a directional rotor like conventional windmills, which must change direction to face the wind, the QR uses three S-shaped blades which twist around a vertical axis, allowing it to be driven by wind originating in any direction. Because the blade tips are closer to the mast body than conventional windmills, silent windmills displace less air, resulting in less total noise.
Two commonly stated problems with windmills is noise and eyesore factor. Silent windmills attempt to bypass both these concerns, by incorporating a silent design and looking more elegant visually than conventional windmills. The silent windmills being manufactured by Quiet Revolution put an emphasis on the vertical element, allowing them to be more easily integrated into preexisting masts and buildings. The helical design is meant to break down violent gusts of wind, minimizing vibration and noise. The QR5 is meant to be integrated into urban environments, where silence is a priority and space is scarce.
Because silent windmills based on a helical design are able to exploit wind currents from different directions easily, they are ideal for urban environments where wind directions change frequently. The entire assemblage is made from carbon fiber, one of the strongest materials available in commercial quantities, which explains its cost. Like other silent windmills made of similar material, the QR5 can be hit by a baseball or flying debris with minimal resulting damage.
Wind power is also preferred to fossil fuels in many contexts because government subsidies are frequently available. Governments want their citizens to transfer to renewable fuel sources to boost long-term energy security for their country.
