Small wind turbine. Noise? Noise cancellation?

Question

Background: A relative is the process of renovating - more like rebuilding - an old, fairly isolated house. It's in a bit of a strange situation... its high up, built into the side of a hill, and the new layout means they've excavated a 'channel' into the side of the hill [3000+ tons worth] in order to extend the ground floor.

Opportunity: The works have created, above the garage, at top-floor level, down the full side of the house, a 'channel' 15ft wide, 30 ft long. It acts as a real wind tunnel. Even on a calm day theres quite a breeze. IMO easy the 10mph needed to start producing power. Obv a wind survey needed to confirm.

My idea to them: Put one [two?] fixed [in azimuth] 6ft turbines in the channel. Ground mounted, easy to install./maintain. Maybe add 2kw to their existing

2.5kw solar array they have tucked away on the garage roof.

Their objection: Noise! It will be only 10ft away from bedrooms, and lounge on the ground floor.

Any ideas? Some sort of baffle/barrier? Or, how about ACTIVE noise cancellation? Can it be fitted to an external wall?

Thanks for any suggestions.

The Natural Philosopher · Accepted Answer

Ducted fans.

not a tunnel. Roof it and put a fan inside some ducting.

Most of the noise of a wind turbine is tip vortices spilling off the blade edges. Than and subsonic thumps when a blade wake crosses the tower.

Ducted fans control the tip effects. still get the thumps but this would be smaller scale/higher frequency and easier to shield. Optimal tip speed for a turbine is around 180mpoh, so you cam work out operational RPM from that.

OTOH there is very little energy in wind so if noise reduction is the desired outcome, try using baffling - lots of little obstructions to slow the wind down. Or simply a structure to push the wind upwards over the top of the building

harryagain · Answer

I don't think it will work. Too much turbulence close to ground/building etc. Also,  possibly dangerous to children/the unwary/stupid.

Martin Brown · Answer

Sounds like it would make more sense to alter the channel profile or add a shelter belt so that the channel isn't quite so windy. Wind noise can be annoying in an exposed building in a quiet location...

They have a good point. The turbine whine at that distance and the tip vortices will be more than a little annoying and the ticks as the blade vortex interacts with the supporting structure will be hard to shield.

I expect 6" of dense rockwool would stop most of it.

I wouldn't want a wind turbine that close to my bedroom. I'd be looking at putting one on a mast at least 30m from the building and downwind. (based on prevailing wind conditions)

Mark · Answer

My recommendation would be to forget the wind turbine.  Generally their output is disappointing and you may find you never recoup the installation/maintenance costs.

Simon Cee · Answer

Thanks for the replies chaps. I thought I was being a bit optimixstic.

Small wind turbine. Noise? Noise cancellation?

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