a smorgasbord of wind gennys [RE-wrenches]

[Ian Woofenden, Home Power]

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Hi Marco,

See the next issue of Home Power (in the mailstream now) for Mick 
Sagrillo's comparison article on home-scale wind turbines.

Three notes on the Ocean Solar system:

1) These are _very_ small turbines. It's not mistake that SWWP calls 
their machine a "wind module". On a very good wind site, the output 
may equal that of your average PV module. On other sites, it can 
contribute significantly less than that. Swept area rules, and these 
machines have very small swept areas. We do not expect a 3 square 
foot PV to produce gobs of energy, and we should not expect that of 
very small wind turbines either.

In many cases, your money would be better spent on another PV module. 
Too many systems have no metering to show the relative value of the 
generating sources. Casual observers see the kinetic wind turbine and 
are impressed, while totally overlooking the PVs, which are generally 
the real workhorse.

2) Roof mounting is questionable at best, and certainly not the way 
to get maximum output out of a wind generator. Standard industry 
advice is to install wind turbines 30 feet above anything within 500 
feet. Bending, breaking, or brutalizing this rule will result in 
decreased output, and often decreased turbine longevity due to 
turbulence.

3) Focusing on peak output of a wind turbine is a big mistake. 
Manufacturers use different rated wind speeds, which makes it hard to 
compare.  And even on good wind sites, you don't see the peak often. 
And since the output is related to the cube of the wind speed, 
cutting the wind speed in half will cut your output eight times. So 
that "400 watt" wind turbine becomes a 50 W wind turbine in more 
normal wind speeds. Swept area is a much better way to compare 
turbines.

I hope to see some of you at Solarfest in Vermont this weekend.

Best,

Ian

PS - I'm in love with the African Windpower machine. It has an 
unimpressive peak output and an impressive total energy output.


>I found the info below, provided by our friends at Ocean Solar in 
>Oregon, very interesting as a comparison between mainstream 
>~400-watt wind generators.  Any other comments out there on 
>favorite/preferred wind gennys?
>
>We investigated numerous turbines, and decided to run some tests. We 
>liked the AIR-403 from Southwest Windpower (SWWP) 
><http://www.windenergy.com/PRODUCTS/air403.html>, because of the 
>high power output for its size (rated at 400 watts), and the ability 
>to throw a "stop" switch and greatly slow the unit. Unfortunately we 
>found the machine to be unacceptably noisy, and there were stirrings 
>of a neighborhood rebellion.
>
>As well, we placed a couple AIR-403's several feet back on some 
>south-facing roof dormers for architectural reasons-only to see the 
>dramatic results of turbulent air. The turbines swung wildly around 
>in the "dirty" air. It was obvious that because of its loud sound 
>the AIR-403 would not work in a residential neighborhood. It was 
>also obvious that regardless of the turbine we used we needed to 
>make sure it was located in a zone of smooth airflow.
>
>A much better location was identified on the west main roof of the 
>house, which placed our prospective turbines in smooth air. With 
>this place in mind we next tested the Ampair Pacific 100 generator 
><http://www.ampair.com>, considered to be exceptionally quiet and 
>ruggedly built. This turbine proved to be much more quiet than the 
>AIR-403, though not very powerful at a rated 100 watts, and without 
>the ability to significantly slow the turbine in high winds if we 
>wished.
>
>After some weeks of testing it was felt that the Ampair was still 
>not quite quiet enough for this neighborhood. We also found that the 
>vibration from the turbine into the structure was unacceptable, and 
>sought to rework the mounting system.
>
>After hearing about the new AIR-X from SouthWest Wind Power 
><http://www.windenergy.com/PRODUCTS/airxmar.html>, we decided to try 
>this unit. We were encouraged by the SWWP web site, and the 
>suggestion of a SWWP technician. At low to moderate wind speeds the 
>unit seemed as noisy as the AIR-403. We had heard that the noisy 
>high-speed "flutter" had been eliminated from this unit, but we 
>ruled this machine out immediately because of a loud 
>"swishing-whooshing" sound heard throughout the neighborhood. In a 
>residential setting this unit was unacceptably loud, even before we 
>reached higher-winds. It is far from the "neighbor friendly" that 
>SWWP advertises.
>
>Finally we tried a couple Rutland 503 generators 
><http://www.marlec.co.uk/products/prods/rut503.htm>, small marine 
>turbines that produce very little power (maximum of 50-60 watts in 
>high winds). These units are exceptionally quiet, though they still 
>reminded us of the vibration issue. For now we are reworking parts 
>of the mounting system, and plan to use the Rutland units as 
>"placeholders" until we have access to a quiet, low-vibration, more 
>powerful turbine.
>
>Note that all wind turbines were tested under load (connected to a 
>battery), and in a range of wind conditions. While we found some of 
>the units, especially the AIR-403 and AIR-X, to be unacceptable in 
>this location we feel that they have their place-but not in 
>residential neighborhoods!
>
>We hope that Southwest Windpower, and other wind turbine 
>manufacturers, put some of their resources into evolving generators 
>that are truly "neighbor friendly." We believe that such a machine 
>will be much in demand, and could allow more wind turbines to sprout 
>in residential neighborhoods.
>
>
>
>
>Marco Mangelsdorf, Ph.D.
>Marketing and Sales
>ProVision Technologies, Inc.
>69 Railroad Avenue, Suite A-7
>Hilo, Hawaii 96720 USA
>(808) 969-3281, fax 934-7462
>www.provisiontechnologies.com
>
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-- 
Ian Woofenden <ian.woofenden at homepower.com>, Fax: 360-293-7034
Associate Editor, Home Power magazine, The Hands-On Journal Of Home-Made Power
Editors are Professional Idiots - We misunderstand text so our readers won't.

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