Your Questions About Wind Turbine Generators For Home Use

admin answers:

Don,

The noise made by a wind turbine has two sources. First is the actual rotation of the blades cutting through the air and the second is the mechanical noise of the gearing mechanism and generator housed within the nacelle (the white box on the top that houses the mechanics).

Nacelles are well insulated and you would have to be very close in order to hear the sound, so close in fact that even stood at the foot of the turbine you probably wouldn’t hear it.

Most of the noise comes from the turbine blades themselves, these are manufactured in such a way as to minimise noise impact. However, no matter how good the design there is always going to be some noise.

You didn’t say how far away the turbines are going to be from your vacation home, this makes a big difference. I’m assuming there will be several hundred metres, particularly as the windfarm will be offshore (in most countries there has to be a minimum distance between the turbines and any buildings).

The amount of noise that a modern turbine makes at a distance of 400 metres is about 35 dB(A)*, at 1000 metres it’s about 15 dB(A).

For comparison purposes 35 dB(A) is about the same noise that a quiet office air-conditioning system will make or the background noise inside a typical house (humming electrical items, heating system etc).

Given that the windfarm in question is going to be an offshore one, then I very much doubt you’ll hear anything. Partly because it will be some distance away and partly because any noise it makes will be masked by the sound of the sea itself.

I think I’d be more inclined to be concerned about the visual impact the turbines may have, and again, it depends very much on the distance. Some people find them to be aesthetically pleasing, personally I don’t.

One of the main factors that influenced our decision to move to where we now live was the view. We’re fortunate that the house overlooks rolling hills and green valleys with very little in the way of visual intrusion, if a windfarm were visible, even several miles away, I personally think it would have a significant impact. That however, is just my opinion, yours may be different.

* dB is short for decibel, it’s the measure of magnitude of pressure variation within the air. Environmental noise impacts are normally corrected to reflect the sensitivity of the human ear, this is what the (A) refers to.

admin answers:

Vertical wind generators are poor performers no matter how they are made.

There is a very recently published book that you should read called “Home brew Wind Power, and you can get it here http://www.otherpower.com .

You can also find a good review at http://www.rebelwolf.com/images/review.pdf

I was just about to write up a review on my web site – but found this question and thought I would save you a lot of grief.

The book title is perhaps a little misleading because it goes beyond what you’d consider “home brew”. These people have excellent engineering skills and their work is the state of the art.

These guys are serious — they work through the technical and physical design considerations (including discussions of vertical axis units) leading up to designs that actually work and even get into the detailed designs of creating the alternator from scratch. It also has links to an enormous amount of reference material.

You mention on buildings or around campus. Please be aware that the generator needs to be 30 feet above the buildings and the tallest trees to get decent power. Start by erecting an recording wind instrument on one of your existing communications towers (don’t get zapped) and find out how much wind you really have. Then calculate the maximum theoretical capacity using the equations in the book and you will find your answers.