Vertical Axis Wind Turbine

Wind Turbines are an effective way of harnessing energy from a natural source. Many companies are looking into 'green' energy alternatives as the price and cost to the environment of fossil fuels rise. 

We are a team of second year Product Design Engineering students from Glasgow School of Art and Glasgow University.

Our aim was to produce the most efficient wind turbine out of the time and resources we had at our disposal. We researched many different designs and developed them until we reached our final solution.

Our design is based around a purpose built wind tunnel that we used to test our concepts and final design. The dimensions given could be scaled up or down depending on the application.

The following step-by-step guide will show you how you too can produce a cost-effective wind turbine.



Materials:

medium-density fibreboard (MDF)
sheet aluminium 
extruded polystyrene foam
hardwood dowel
ball bearings
two bought-in gears
bought-in generator


Joining techniques:

panel pins
screws
PVA glue
hot glue sticks


Tools:

power drill
hand-held jigsaw
sand paper
hammer
metal file
tin snips
allen key
hot glue gun
bandsaw
sheet bender
guillotine
router
belt sander
hole punch

Step 1: Fan Base

The fan is one of the most important components in this design.

The MDF base is made of two 300mm diameter discs, with a 260mm diameter disc in between - all 18mm thick. These were roughly cut to shape using a bandsaw and then accurately sized using a belt sander. A hot glue gun and 30 x 1.6mm panel pins were used to attach the discs together.

The lower-most disc was cut to size the same way as the other discs. This disc had a 155mm outer diameter channel cut out using a router. The channel is for the ball bearings to run and its width was 6mm (chosen due to the ball bearings purchased).

Through all four discs is the hardwood dowel axle - 22mm in diameter - cut to 240mm in length using a bandsaw. A hole of the same diameter as the axle was cut through all the discs using a pillar drill. The axle was forced through and required no glue due to the accurate fit.

Step 2: Blades

The blades were cut to shape, using a band saw, out of a 1mm thick sheet of aluminium. The rough edges were filed and holes of 4mm diameter were punched. The two straight edges were bent using a sheet bender. Tin snips were used to cut out the folds where the screws would go through and the triangle sections - this was done so that the blade could be curved. The whole blade was curved by hand and a rubber hammer. They stand 186mm tall after bending.

Holes through the base of diameter 3.5mm were drilled with a power drill. The blades were screwed on in two places per blade, and an allen key was used to tighten them as much as possible. The screws were 20mm long and 4mm diameter (7mm head).

Step 3: Base

The base is simple and quick to construct, but needs to be accurately made.

The base was made out of a 415 x 340mm piece of MDF (medium density fibreboard), 18mm thick. A hole was cut into this base using a router. A disc of diameter 320mm was then sunk and glued into place.

A channel of 155mm outer diameter was cut out using a router. The channel is for the ball bearings to run and its width was 6mm (chosen due to the ball bearings purchased). This matches the one cut out of the fan base.

A hand-held jigsaw and sand paper was used to shape the hole in the middle; diameter 115mm. This was so that the generator axle could connect to the gear attached to the bottom of the fan base.

The support stands were cut to the height of 147mm using a bandsaw. This height was required so that the generator and its housing could fit underneath. The MDF stands are 15mm thick and the pieces were PVA glued and nailed together.

Step 4: Generator

A generator with quoted values of 3500rpm and 24 Volts DC was given to us to use; a different generator could be used in your design.

A housing was required to hold the generator in the correct place as well as protect the generator. Extruded polystyrene foam was cut to size using a saw and attached using a hot glue gun. The foam allows slight movement of the generator which is required for efficient running. It also acts as a good insulator as the generator heats up during use.

The MDF housing was cut to size using a bandsaw with holes at either end to allow the generator axle and connections to be reached. The outside dimensions are 67 x 70 x 68 mm.

This was glued with a hot glue gun to the stand which was designed so that the small gear was at the correct height (match up to the big gear on the fan base). An extra styrene piece was heat formed to shape to further protect the generator from the wind.

The large gear was screwed onto the centre of the fan base. Two holes were hand-drilled into the gear and the screws were drilled in. This gearing creates a gear ratio to increase the rpm the generator axle is turning (and hence decreasing the torque).

Step 5: Wind Deflector

Since our wind turbine was designed with a wind tunnel test in mind, a wind deflector was made. The blades are designed (curved) so that the fan will have more force pushing on one side than the other, which spins the fan. A deflector would decrease the opposing force and so increase the speed at which the fan will spin.
This may not be suitable for your application as the natural wind direction cannot be guaranteed and so the deflector may be ineffective.

A 1mm thick aluminium sheet was cut with a guillotine to a height of 260mm. Tin snips were used to cut out the folds and triangle sections and a sheet bender used to bend these parts to 90 degrees. The sheet was curved by hand to match the outside radius of the fan base.

Holes of 4mm were punched into the folds for the screws (same as for the blades) to go through. The base was hand drilled for the screws, which were tightened using an allen key.

Step 6: Conclusion

Due to our application we have not connected the generator to an output. However this could be simply done using electrical wires connected up to the generator at one end.

We hope you found this instructable informative and easy to understand.

Any questions or advice on design changes are welcome, please comment below.

Comments

[kbs2244]

I am woundering about carveing up 2 liter soda bottles for the blades?
Was that large curve at the top just for looks or was there a tech reason for it?

[butterworthmeister]

As far as I can tell from my own research, the vertical tapering of the blades means that the wind will bleed off at higher velocities, meaning the turbine will never spin out of control. Additionally, they produce, on average, at least 33% greater torque than a conventional barrel design, especially at lower wind velocities

[WindyNeurone]

Hi guys.
You could force the deflector to rotate around the turbine and its centre by using a fin. Similar to oeizzontal wind turbine

[churn]

Let's pretend we won't lose more than 50% through material, design, and conversion inefficiencies before we even get moving.

We can get an amount of power from the windmill exactly in proportion to the wind force pushing against the blades. This means, if we recovered half the power it took to drive 60mph, the windmill would be creating exactly that much wind resistance for our poor motor to push through. What we gained through the windmill would have to be spent to keep the vehicle going at 60mph.

Realistically, we would lose several times more than we gained through inefficiencies, and at best break even with an additional time and material expense.

Perpetual motion is less important than being able to strap a harness to the forces all around you all the time. Even the best designs for perpetual motion machines only redirect another force to propagate the desired force.

[chubby8]

Vertical axis wind turbines (VAWT) are a real and effective way to generate electricity from the wind. They are not perpetual motion machines.

They are designed so that the blades have more wind resistance in one direction than the other, and as they rotate on a vertical axis they will always achieve a net rotational force, no matter what the wind direction (asuming the wind direction is not perfectly vertical, which is unlikely in a natural situation).

The wind speed will have to be high enough to provide enough force to overcome the friction and resistance of the generator before the turbine even begins to rotate.

There will be losses of effiency over design and other factors, especially on tight budget and time restraints, but in a high enough wind speed this design will generate some electricity.

[vtstruct]

Very nice design. The aesthetics are great -- I hope it works well!

[akashpatel]

how to join the bearing in construction

[trallimann]

Isn't this somewhat similar to http://www.icewind.is/images/mini.jpg invented in 2007-2008

[Kardolf]

I would love to hear how much power this design actually produced. Did the curved tops of the fan blades have any impact on power output? My first thought was that they would not hold the air as well, and would reduce the output, but perhaps the lower mass or allowed for a higher speed, and more output?

[dimtick]

I read about a commercial version of this in which the blade unit used magnets so that it would litterally float above the base unit. the claim is that this reduced the spin friction down to next to nothing so that it would spin and be very efficient in very low wind speeds.
Another advantage that was claimed about this design is that in urban envirnments with buildings and trees that low level winds are very turbulant and constantly changing direction. traditional blade designs can't handle this low level turbilance which is why they're mounted up high on poles so they can catch clean air, but this design can be mounted at ground level with no loss of efficiency.

[JayGeeBSE]

You are severely mistaken. Windspeed rises from ground level up to say 100 - 200 feet. Any wind driven device at ground level will get greatly reduced wind speed to use. There is no substitute for getting the device as high as possible.

[dimtick]

my comment was not about wind velocity. it was about low level turbulance.
higher is better but there are lots of places where it's not possible like in urban or residential areas. vertical axis blade designs easily adapt to rapidly changing low level wind direction.
I did a quick google search for the turbine similar to this that i remembered. it appears that the company has gone under but here's the article.
http://www.greengeek.ca/magnetic-levitation-wind-turbines-now-available/

[JayGeeBSE]

What you wrote was "this design can be mounted at ground level with no loss of efficiency.". It can't.

[dimtick]

the problem here is your confusing my use of the word "efficiency" with "output". in this case efficiency refers to how the turbine performs in changing wind directions versus how it would perform at the same wind speed and the wind was coming from a constant direction and the turbine was perfectly aligned with the wind. this is not about what the output potential is of a low level turbine versus a output potential of a high pole mounted turbine. vertical axis turbines do not care from which way the wind blows so if the wind changes direction the turbine is still producing at 100% of what it can produce at that wind speed. there is no loss in efficiency. with a propeller turbine if the wind changes direction it'll only be producing at a fraction of what it could until it can orient itself. I'm sure that turbine designers have a term for this other than efficiency that would avoid this confusion but i don't know it.
does that make sense?
sorry for the confusion.

[JayGeeBSE]

A generator with rare earth magnets should be more efficient. As should a device with no brushes. Maybe a brushless motor used for model aircraft would work better - these have the magnets and no brushes, but generate 3 phase so would need diode rectifiers.

Putting a heat insulator round the generator is a bad thing - keep it as cool as you can.

[hjjusa]

Could something like this be put on an electric car powering a generator which in turn recharges the batteries?

[churn]

Let's pretend we won't lose more than 50% through material, design, and conversion inefficiencies before we even get moving.

We can get an amount of power from the windmill exactly in proportion to the wind force pushing against the blades. This means, if we recovered half the power it took to drive 60mph, the windmill would be creating exactly that much wind resistance for our poor motor to push through. What we gained through the windmill would have to be spent to keep the vehicle going at 60mph.

Realistically, we would lose several times more than we gained through inefficiencies, and at best break even with an additional time and material expense.

Perpetual motion is less important than being able to strap a harness to the forces all around you all the time. Even the best designs for perpetual motion machines only redirect another force to propagate the desired force.

Men tried an idea like this in the past and called it a sailboat, but it was not very effective in a headwind.

[rimar2000]

That would approach too close to perpetual motion, I think it is impoosible.

[Richie15]

Nope, not perpetual motion as the energy's being transferred from the wind to the car, then to the ground (oversimplified, I know - I'm no physicist).

It's no different to a solar-powered car (which I know works on a small scale, at least) and I can see no reason it wouldn't work.

I do understand why it looks like perpetuity - the car's forward motion would effectively create a wind over the blades, which may cause them to spin. But it's mainly the real wind rather than the relative wind which is driving the fan.

[tcarney57]

Solar power captures energy so completely out of the car-turbine system that it's literally extraterrestrial! Almost all the energy to turn the turbine at road speeds would come from the car itself--from gasoline/petrol or diesel fuel. There might be random (spelled in all caps!) input from absolute wide sources, but wouldn't it be just as likely that whatever net energy gain to come at one moment (and direction) be canceled the next moment by drag?

Somehow collecting and using the huge amount of energy wasted by internal combustion would be pretty cool, though. Years ago I gave a lot of thought about ways to collect and store some of the engine's lost heat radiated and blown away---no doubt a big chunk of the total energy released from the system.

I thought a lot about using tanks of phase-change material (Glauber's salt) to store heat that could then be released by exchangers into a domestic hot-water system--essential using it to preheat the cold-water side of the water heater. I got far enough to discover a few chemo-mechanical issues--some means of stirring and reconstituting the material would be needed to maintain its energy capacity. Also, losses from the additional vehicle weight would cancel out at least some of the salvaged energy. Oh, and who wants torpedo-like tubes of "heat batteries" strapped to the top of his car?

Alas, that was many years ago and I've given no more than a passing thought to the idea.

Todd