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Renewable energy sources have diverse origins, a feature that demands equally diverse technologies to capture them. My interest in these (new) technologies resulted in this blog. If will focus on well developed technologies that are already put into practice, and on promising technologies that are still under development.

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Saturday, June 23, 2007

Quiet Revolution, an elegant wind turbine for urban environments

Source: EcoGeek, XCO2

The quietrevolution (QR) was designed in response to increasing demand for wind turbines that work well in the urban environment, where wind speeds are lower and wind directions change frequently. The siting of any wind turbine is crucial to the output that can be expected from it. Ideally, a wind turbine would have no obstructions between it and the prevailing wind direction.

Of course, in an urban or built-up environment, some wind turbulence is inevitable unless the turbine is sited well above any surrounding buildings. Most of the time, turbulence from surrounding buildings will affect a wind turbine to some extent. This is the primary reason for opting for a vertical axis wind turbine, as such a design doesn’t require wind from a consistent direction to continue producing power. Conversely, a horizontal axis wind turbine has to physically rotate into the wind every time the direction changes, wasting valuable resources.

Typically, reasons for wind turbines causing disruption or being refused planning permission include its visual impact, noise and vibration. The QR turbine’s elegant design is geared towards adding visual appeal to its surroundings, and the aerodynamics of the vertical axis design mean that noise and vibration is reduced to near silence.

1 comment:

Eric said...

The following passage is excepted from a letter by Mick Segrillo, the expert called on by the American Wind Energy Association (AWEA) to answer questions about small wind.

The full letter can be read here:
FYI, even though this letter is a few years old, we have yet to see production data from these machines or anything that should change our approach.

Why does anyone with any credibility at all in the small wind turbine industry just roll their
eyes with each new pronouncement? A conspiracy by the conventional wind turbine
manufacturers to exclude threatening vertical-axis innovations and competition perhaps? I
think not. Let’s look at the claims made by the Web sites.
• “Can take wind from any direction.” So does any conventional wind turbine. The
only difference from a conventional turbine is possibly the addition of a tail on an
upwind horizontal axis turbine.
• “No tower required” and “designed to operate much closer to the ground than
prop turbines do.” Please learn something about fluid dynamics, that branch of
physics covering air flow over things like trees and buildings. The last time I checked,
no one on planet Earth was exempt from the laws of physics. Maybe your design
doesn’t incorporate a tower, but you are not going to generate usable amounts of
electricity without one. Hint: manufacturers of horizontal-axis wind turbines do not
put their turbines on towers because they are concerned about killing cows in the field
in which the turbine is sited.
• “Allowing for ease of maintenance on the generator.” Generators and alternators
are the most reliable part of any wind system. The components that need attention are
usually the blades, rotor bearings, and governing device, all of which become more
difficult to access with many vertical axis designs than their horizontal-axis
• “Small rotor profile.” The rotor is the “collector” of any wind turbine design. In a
solar system, if you want to double the amount of energy “collected” you double the
size of the collector. The same holds true for wind. Fact: the amount of energy
extracted from the wind is more dependent on the size of the rotor--that is, the
collector--than any other part of the wind turbine.
• “Mounts on your roof.” Have any proponents of such a practice ever performed an
engineering analysis on a given roof to determine if the structure can sustain such
loads? If not, prospective purchasers might want to check in with the home owners
insurance company to see if it will honor the inevitable claim for damages once they
• “Urban turbine.” This is, by far, one of the most clever clich├ęs about wind conjured
up in decades. The only problem is the lack of a suitable wind resource in urban and
suburban areas, followed closely by the unpredictability of the wind due to the
turbulence created by the extensive and complex ground clutter.
• “Improved aerodynamic performance.” Most claims tout unachievable
performance by any wind technology, irrespective of blade orientation, based on the
laws of physics that the rest of the planet is bound by. In addition, there is no
information offered to back up these claims—who did the testing?
• “Bat and bird friendly.” The implication is that small horizontal axis turbines are bat
and bird hostile. Where is the data substantiating either the claim or the implication?
• “No ice throws.” Fact: small-wind horizontal axis technology cannot throw ice either.
• “Will not interfere with telecommunications.” Again, the implication is that
horizontal axis technology does interfere with telecommunications. Fact: one of the
largest niche markets for small wind turbines is powering telecommunications,
particularly at remote sites. They would not be used if they caused interference.
• “Or aircraft navigation.” Is there any evidence that any small turbine, regardless of
blade orientation, interferes with aircraft navigation?
• “Energy efficient.” This is an energy generator, not an energy-consuming appliance.
Energy efficiency does not apply.
• “Excellent cost saving features.” Such as no tower? Although most people do not
realize it, what they should be interested in is not up-front cost, but life-cycle cost of
energy generated over the life of the system. Cutting out, for example, the tower,
means that the amount of electricity generated, along with the economics, plummets.
• “Investment opportunities available.” Quite often, this is associated with the prompt
to “get in while you can, on the ground floor.” We may, at this point, be getting down
to the real purpose of the Web site. Hint: legitimate wind turbine manufacturers do not
sell dealerships or distributorships.
• “Patents applied for.” If every wind turbine with a patent were available on the
market today, we’d be awash in such “innovations” as giant revolving castanets,
opening and closing based on their orientation to the wind and merrily clapping away
in the breeze like happy clams. Fact: a patent is only a legal protection for an idea that
no one else has yet patented. Holding a patent does not mean that your invention will
actually generate electricity, which, after all, I assume is the purpose of the