Ebike Hub Motor And PVC tube Wind Generator Design

[SniperGaulois]

An ebike motor can put out 50-100W @ 14 V ... I want a 30W+ wind turbine for my friend so she can charge a lead battery away from the grid.

I am tempted by a vertical axis VAWT made with 2 bike wheels joined together by wind foils made of PVC tubes. I have a xlite 406 motor, and I am wondering about the best length of PVC tube and the best design to have the optimum speed to convey to the motor.
[youtube]dl6m4emdeBI[/youtube]
For example, the PVC tubes could be 1m long or 2m long, and they could be on a rotation diameter of 24" or 28", and I'm not sure how that would affect the speed and power transmitted to the hub motor.
Can you advise on the best velocity, catchment area, and circuitry for an ebike motor generator?

With the number of hubs some of us have at home, we could probably run the whole house off the grid with a line of wind generators in the garden?

This is an orthodox wind generator made simply, although it's more difficult than the above one:
http://www.youtube.com/watch?v=YXpxOv_W2AM

 

[arkmundi]

An ebike motor can put out 50-100W @ 14 V ... I want a 30W+ wind turbine for my friend so she can charge a lead battery away from the grid...

Interesting idea, or has this actually been accomplished and been put to use? More info, please, if available.

 

[SniperGaulois]

there are many videos on youtube of generators using PVC tubes and bike wheels, and here is a wind gen using an ebike hub:
http://www.youtube.com/watch?v=BxRzlclRIHs

 

[Samd]

Use a Lenz VAWT for low speed wind locations.

Use a HAWT with 5 or 7 blades for mid-wind speed locations.

Use a HAWT with 3 to 5 blades for high wind speed locations.

I can give you the formulas for size if you give me the local wind speed at the height you intend to mount at....

 

[arkmundi]

I love the idea and would like to see it fleshed out more ....
[youtube]OD1gSx92DuM[/youtube]

 

[SniperGaulois]

I can give you the formulas for size if you give me the local wind speed at the height you intend to mount at....

Thanks! average windspeed is about 4mph, 6kph, useable speeds vary from 5 to 15mph most days, not often above 20mph. it's on an exposed hillside, with some trees, i was thinking just 2-3 meters above ground would be cool. VAWT sounds great because it could be made in a day with the readymade axis. what is the most best size and diameter for a ebike hub?

 

[Samd]

Forgetting the alternator for a moment, that is a lower wind speed so definitely VAWT territory. Design the rotor size first.

Imagine holding up a 1m square empty frame with 6kph (2m/s) wind running thru it at 1.4kg per cubic meter of air. The energy available to capture =0.5 × 1.4 × 2*2*2= 5.6 watts. The BETZ limit says you can capture about half, or 2.8watts. For fifty watts at that wind speed you'd need a rotor 25 times the size, say five meters high and wide.

The energy in the wind is a cubed relationship. So a 1 meter high&wide rotorrotor at 30kph, or ten m/s, the energy would be 0.5*1.4*10*10*10=700 watts. You can catch half so maybe 300 watts. It'd be an ok match for a DD hub.

Consider one of ED lenz's designs, its kind of a HAWT/VAWT hybrid.

Consider solar at about a dollar a watt. You'll get an easier project but less fun.

If you persist with wind you'll need to learn about changing star/delta wiring to match the system voltage. Join VAWTS.net. You'll learn heaps.

Charge regulators for wind used to be dear compared to solar but are getting cheaper now on fleabay. Consider using a nema stepper motor to start generating, or an outrunner motor, then try scaling up. Cat 5 ethernet wires make ok low power cables.

If your dd hub makes a lot of volts at low revs don't worry too much about hooking it up to a deep cycle SLA, it'll hack it if the charge controller can too.

Good luck.

 

[SniperGaulois]

Thanks, it's brilliant when someone knows very precisely the maths and measurments and the mass of the air. i

What do you mean about a nema stepper motor to start generating? does it generate electricity for a smaller version?

Solar makes more sense, the wind gen would be prettymuch free though other than the price of a voltage regulator for the battery, can you make a guesstimate of average kwh every week for a zone with average of 5.9 kph of wind? equivalent of just 50 dollars of solar panels? i like the lenz version with the plastic tubes for the round area and the some straight areas made from plywood. I'll post images of it once it's constructed!

 

[Arlo1]

Think I'm going to build one of these.