silent wind turbines

[ehsmeng]

Hi,

Considering a move to a windy place. So playing with wind turbines has crossed our minds.

We're thinking of some 5-10kw peak system. Most likely in a suburban type of area so having a silent rig is an absolute must.

Puzzling lies and exaggerations in ads, I'm under the impression that vertical axis ones are more silent (if the blades and not strictly vertical but instead rounded like JRRT elf writing. Is this true?

I've also seen some more modern looking conventional propellers where it looks like someone bothered to do an aerodynamics simulation before producing. Compare with when airplanes started to get modified wing tips some 25-30y ago to avoid the loss of lifting power cause by the turbulence. Are these more silent or is it just a showoff thing?

Thanks,
Marcus

[Neilm]

Which type of turbine is best very much depends on the location. The biggest influence on this is how smooth the air flow is. A few people I know were looking at putting in a small turbine, but when the site survey came, the surveyor noted that the wind flow would not be smooth enough for a good performance.

Also, I believe that the vertical wind turbines need a small motor to get them to start spinning, so they don't work very well in light winds.

[wazzokk]

I was interested by the previous comment about vertical axis needing spinning up. It tallys with something I have noticed travelling around the UK, quite a few small sized vertical turbines but they are almost never turning! This includes when nearby conventional turbines are spinning quite quickly. I know this is not a quantitive assessment, just my observation.
Regards Dave

[mtdoc]

Small wind turbines are a minefield of marketing hype and unrealistic expectations.

Maybe worthwhile IF you live were conditions are right - which is not most places.  In the suburbs?  You will need a very large tower to get the turbine high enough above all surrounding structures.

For sound advice from some with experience, i recommend The OtherPower Forum

[LabSpokane]

The pros call anything under 20kW "recreational wind."  There's nothing remotely economically viable less than that size.  The small turbines are good for sailboats and remote locations as a compliment to solar.

And a tower tall enough to be effective in suburbia likely won't be permitted.

[m100]

For 'DIY' wind turbines

http://www.scoraigwind.com/

Particularly

http://www.scoraigwind.com/pmgbooklet/itpmg.pdf

Design is scaleable but not to 10kW!

There is also a mailing list on yahoo groups with quite a bit of info in the archives / file area

https://groups.yahoo.com/neo/groups/axialflux/info

Useful site with lots of reports (UK based but

http://www.wind-power-program.com/index.htm


None will be silent, anything around like strucutures and trees means a huge decrease in output without lifting the hub height, output is miserable (always) and vertical simply doesn't work, ever.

[Dave Turner]

Define silent. Silent and turbine 'does not equate'

[G7PSK]

I built a small wind turbine for my fathers house about 15 years ago. It is a Bergey  1KW unit on my own tower design and it runs very quietly indeed. I changed the bearings this year the first time ever not due to wear but I had the thing down anyway to replace the brush and slip rings which had worn out.
The thing is most of the noise in small turbines comes from vibration caused by the tower not being rigid enough. I came up with what I call the rigid stay system where there is a single central tube to the tower and four smaller tube stays which have screw adjustment at the base. When these are tightened to the point that all internal stresses are greater than the external stresses there is  no vibration and very little noise and it is the vibration that throws the bearings in most rotating machines. It dose however require 3 cube M of concrete and an RSJ frame for the base.

[johansen]

5 and 7  bladed turbines have the potential to be quieter than 3 bladed turbines because they spin slower.. they also don't extract as much power, and require a larger generator due to slower rpm.

Downwind turbines make a lot more noise because the air flow is disrupted by the tower.

its hard to define noise when comparing vertical with horizontal wind turbines.. you mean noise per square foot of turbine, or noise per kilowatt hour generated.
personally, i won't bother with vertical wind turbines, they are simply not very efficient.