Wind energy for the home

[npts2020]

Check out these commercially available home wind generators. http://www.treehugger.com/file/2008/11/five-home-wind-turbines-you-can-actually-buy.php

[CaptainPanic]

Umm...

Any discussion points? Questions? Bold statements?

 

If you have none, I'll just throw one in: The energy-payback time of those small windturbines, including the adaptations you need to plug it into the net, or to provide some energy storage is longer than the lifetime of the turbine.

 

(I didn't calculate it, I'm just guessing - but at least there's a discussion now - you're welcome).

[gcol]

Yes, commercial wind turbines are very expensive on a cost per watt basis, and that is just for the turbine. The battery storage and control circuitry is a whole extra money-pit.

 

Unless you live on a really large plot in an area of medium to high windspeed away from whingeing neighbors or are off-grid so that anything is better than nothing, then they barely get out of the "street-cred" or "green cred" area.

 

For a couple of years I have been lashing up various experimental configurations (always with the main aim of minimum cost and mechanical complexity).

 

In a nutshell I can definitely say that with windpower, size is definitelyeverything, and if capital expenditure is an obstacle, then DIY is the way to go but no guarantee of success without much hard work and many setbacks along the way.

Edited December 3, 2008 by gcol

[npts2020]

Some of the turbines pictured cost as little as $500, if one provided only 10% of my electricity, it would pay for itself in 4-5 years, so wind generation is quite competitive where I live. Furthermore I expect the prices to go down substantially as production gets ramped up, what other forms of electrical generation are likely to become cheaper?

[CaptainPanic]

Large scale wind turbines (the >1 MW turbines) nowadays cost about 1 euro / Watt (peak power). Or was that dollar? Hmm... anyway, that order of magnitude. Most likely depends on where you want to build them, and where you buy them.

[YT2095]

when I used to live in a highrise there was always plenty of wind on the balcony, so I made a small wind powered generator (just for fun) out of a 2l plastic soda bottle and a small motor out of a video eject mechanism, it was enough to light a couple of LEDs, so you could probably keep a mobile phone battery topped up with it.

it would be impractical for general use though as the weather (esp Rain) would screw up the motor pretty quickly, but as Proof-of-concept, it worked rather well

[CaptainPanic]

And because your wind energy came from almost 100% recycled materials, the energy-payback-time was really short.

[YT2095]

actually, All of it right up to the LEDs was recycled from "junk" I had laying about, I`m sure given a little more time I`d have worked out a shroud to protect the motor, but that would have used sealant that you can`t recycle.

 

I should imagine that having half a dozen of these could be used to charge batteries for some really usable power also, certainly enough for a small radio or calculator etc...

 

the idea`s quite simple too, all you do is slice along the bottle with a box cutter top to bottom between 6 and 8 times and then turn these strips out a little (don`t cut all the way though) then the motor spindle gets rammed into a cork and then the cork into the bottle neck, then you mount this on a bit of wood as a base with another wooden post running alongside the bottle (allowing room for it to spin) with a nail in the other end of the bottle to give stability.

the nice part is that unlike ordinary propeller blade type fans, it doesn`t matter which way the wind is blowing for it to work

[Sisyphus]

I don't know what the cost effectiveness is, but I would definitely look into it. I'm guessing that in the right place it would pay for itself. I'd also guess that large-scale turbines probably have a considerably lower cost per watt than the rooftop variety.

[gcol]

Homebrewed wind power is a wonderful illustration of the chasms between theory, practice, bangs per buck and wishful thinking.

 

My present one, and largest, is an 8'x1' Savonius type (vertical axis) mounted on a draughty corner of my house. In a medium breeze, I get about 10w from it from my "standard" generator which is a dc motor used in reverse. The Savonius now working steadily and reliably, I am having much fun building and configuring small permanent magnet alternators and comparing their output.

[YT2095]

I just googled "Savonius" and it seems my soda bottle idea is Very similar, only with 6 to 8 Blades instead of the 2.

I think it`s a great design and much better in many ways than the typical prop blade sort, it was thinking of a water mill that gave me my idea originally

[gcol]

Yours sounds as if it might be something of a hybrid between savonius and Darrieus

or even a centrifugal blower in reverse. The general concensus of the red-neck mountain dwelling off-gridders, through experience, seems to be that the horizontal axis traditional windmill type generally gets the most energy from a given moving air mass. The blades will always move faster than the wind because of their aerodynamic properties, but the savonius can not rotate faster than the wind. Because rpm =volts, the traditional mill also has an advantage there.

[npts2020]

The main problem I have in doing cost comparisons is that it is very difficult to get good numbers for longevity and repair schedule of the wind generators. Also, it often gets lost in the discussion of cost/kwh that there are unaccounted for costs in using fossil fuels, even if you assume unlimited supply. If I can find where I read it I will get the url from where someone was home building a 200w generator for under $200 but the point is that if one person can do it at home, how long until someone does it commercially? At that price it seems competitive with any source. One caveat....electric storage which will add cost. As we all know, wind is a variable and intermittent source. There are at least two ways of solving this problem, the most obvious being to store the electricity. Another, and imo better, option is to build the wind generators in a grid large enough that the wind is always blowing somewhere. I have read that an area roughly the size of the British Isles is approaching the minimum requirement for this, and that one the size of the EU or Canada or the U.S. would be more than large enough to accomplish it. Unfortunately, I cant build a grid that big by myself.

[gcol]

That figure of $200 is pure wishful thinking.The cost of neodymiums and magnet wire alone can gobble that up in a mill to produce anything but hobby amounts of power. The blades are hand-carved, the alternator homebuilt usually based on a Volvo wheel/brake hub assembly, coils handwound. You have not included tower, storage batteries, (deep-cycle, expensive,) rectifiers, voltage controllers, etc. Now add in all the unpaid man-hours as well. Do some business studies having regard to normal cost and profit figures, add in the costs of the installation team and if even a very modest 200w outfit comes in, retail, at less than $2500 I would be surprised.

 

The gulf between dreams and reality.

[Flashman]

Just wondering, do you have a link to the webpage of that guy who's using the volvo parts to make alternators? I haven't been able to re-find it after seeing it a while ago.

 

It sounds like your vertical axis rotor is like something I keep wanting to try, I figure that the walls of my house kind of act like a collector for stray breezes and a savonius rotor at a corner may be more effective than having a free standing one. I was hoping to get something like 500W out of something about 12' high by 2' diameter though.

[gcol]

Try Googling hugh piggott and or scoraig. He developed the idea, it is now the most popular homebrew wind alternator system. But it needs higher rpm than you get with a savonius, and the lower axial loads on a savonius don't really need something that beefy. Need larger diam. rotors to get higher rim speed. With 2' dia, blades, why not 2' dia rotor? plenty of room. allows for more magnets than a normal person can afford! On traditional horizontal axis mills they like to keep alternator dia. down to reduce wind drag.

 

There are some really really good discusion boards out there on this stuff. Try "windstuff now" and "otherpower". Reluctant to say more, am fast approaching the limits of newbie idiocy. Don't want to give you wrong info. Good luck.