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DIY Savonius Wind Turbine / Generator

13th September 2013

Autumn has well and truly arrived in England. The nights are drawing in, the sun isn't so bright.
Generating electricity from the Sun is difficult these days.
Don't get me wrong though, some days are really sunny and bright...it's just they're few and far between.

This has got me thinking about Wind Energy.
And I've decided to create some kind of wind generator / turbine to supplement the Solar Panels I have.
I'm presented with two options -
1 - A traditional Windmill style - aka HAWT or Horizontal Axis Wind Turbine
hawt Horizontal Axis Wind Turbine
2 - A less conventional Savonius Turbine - aka VAWT or Vertical Axis Wind Turbine
vawt Vertical Axis Wind Turbine

It's widely acknowledged that the HAWT style of turbine are the most efficient. Depending on the design and build, they can extract up to 50% of the energy from the Wind. They have some drawbacks though -
1 - You have to create some kind of mechanism to ensure it's always pointing into the wind
2 - You have to create some kind of mechanism to ensure it doesn't spin itself to destruction in high winds - this is due to them being a 'lift' design. This means they can go much faster than the wind that is hitting them.
3 - They need a lot of wind to get them going (low torque design)
4 - You will need a lot of space to get them high enough to catch the wind needed to get them going
5 - Noisy - On a windy day, this style of turbine can generate a lot of noise ( aswell as a shed load of electricity :o) )

VAWT on the other hand are nowhere near as efficient. Somewhere in the region of 15%.
But when in comes to construction, they have a lot of advantages -
1 - They don't need pointing into the wind and so will pick up the wind from any direction
2 - They don't really overspin because of the fact they are a 'drag' design. Basically this means they can never go faster than the wind that is hitting them.
3 - Work in very low wind speeds due to the high torque design.
4 - Can be installed much lower, making building and maintaining much easier.
5 - Quiet - Pretty much silent, which is good when living in the middle of suburbia

I'm going to start off simple and small. Something I can attach to my shed, that won't look huge and cumbersome...and won't alarm the neighbours too much!




DIY Savonius Wind Turbine
Bought myself a sheet of 6mm Plywood for £6.50
I don't think it's marine grade or anything like that. I do plan on spraying it when built to protect from the elements.

Found a frying pan that was 32cm diameter...that's what I used as the template for the circles.
Used a standard jigsaw cutter to cut them out.
You're probably wondering why I have three and not two...I'll explain later.

Drilled a 10mm hole in the centre of each.



DIY Savonius Wind Turbine Vanes
Cut out 8 off 12cm x 15cm plates to use as the vanes of my turbine.
I've glued them onto the circles using PVA glue.
I didn't really put any effort to work out angles and stuff...I just used my judgement and my eyes to get them looking sorta right.

You may have noticed I'm being slightly controversial here with my triangular vanes. Pretty much every savonius turbine I've looked at uses half circle vanes.
I can see the logic of cutting a drainpipe in half as it's readily available, cheap and does a good job of being a savonius vane.
But I always like to be different! So I'm experimenting with triangular shaped vanes (cups..whatever you want to call them).
The logic in my mind is that they will be near the same capacity as a half-circle vane, but with the big advantage that on the opposite side to the wind capture side, they will slice into the wind better. Imagine slicing bread with a sharp knife versus a rounded dull knife.
I'm sure there are some science type guys out there who can go into mega detail as to why my design is awesome or rubbish, and I'd love your comments below.




Here it is all glued together.
You'll notice how I've stacked the two sections on top of each other. This gives the benefit of the four vanes being only 90 degrees apart (a single stack, the vanes would have been 180 degrees apart).
Theory is that this will make it easier for the turbine to start.

The fan I used wasn't overly powerful, so I'm fairly happy with the fact it managed to get going using it's pathetic breath of air!

I do have a tachometer, so I'm going to run some tests to see how fast this will spin. This'll give me a good benchmark, if and when I decide to make changes.



Next - Wind Generator MkII



Comments

Jesse - 05/01/2015 18:36:42
you explained how to build the turbine, but what about the generator? How do we build that?

Gav - 18/09/2013 08:45:11
Hi Adrian. The 3 circles is because I am going to stack them on top of each other, but had 90 degree offset. This'll allow it to start easier as it will have more available angles to catch the wind. It'll become apparent...trust me!

Adrian - 17/09/2013 17:19:47
You never explained what the third circle was for? I am quite literally on the edge of my seat in anticipation. The science guys as you call them have binaryorbit.org in the favourites so im sure they will be writing their comments as soon as possible. Why are there so many spelling mistakes for a gentleman with such awesome intellect such as yourself.

Clare - 17/09/2013 14:16:37
It would be good to see a video on here of it in action!

Gav - 17/09/2013 13:33:18
On error resume next is perfectly fine!!!

Simon - 17/09/2013 10:49:31
on error resume next sucks

jack - usa - 17/09/2013 10:07:54
mmmm...Triangle vanes. That's a new one. I cant wait to see how this pans out.

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