Wind power from a bicycle - need technical help

[Michael Fournier]

What I'd like to do is mount a device to my bike to harness the wind energy, and store it for later use.

I've been doing research but can't find any straight forward information on converting wind energy to power, and then storing the power.

[Joe Blake]

Hi Michael,

Welcome to the Board.

Just a couple to questions to settle the picture in my mind.

When you say "wind power" do you mean the wind created by forward motion of the bicycle as you are pedalling, or are you looking to harvest natural wind using a stationary bicycle as a mounting for say a wind turbine?

When you say you want to store the power for "later use", how much later is "later"? A minute? A day?

If you're going to be using a moving bicycle, the question of weight I think must be assessed as well. This would govern how "much" energy you could harvest and store.

There are so many options I think we need to narrow down for field of inquiry a bit.

Joe

[Michael Fournier]

The idea would be to use the wind as I'm pedaling, and I'd like to store the energy for at least a few hours.

I thought about the weight issue as well. I have no idea what components are necessary and thus have no estimate of how much weight I'd be dealing with.

Thanks for the reply. :)

[Joe Blake]

Michael,

In reality the bicycle is the most efficient means of transport EVER created, when you consider how fast you can travel, how far you can travel, how much it costs to build and so on. It's even more efficient than walking, because just the act of standing up is actually using muscle power and will tire you.

Capturing the energy. You'd need to be sure that the amount of energy you are capturing isn't outweighed by the energy you are going to expend, in other words, will it take more pedal pushing on your part to do this than if you didn't have anything on the bike at all and you were able to pedal up a hill faster/ more easily? Eg if (somehow) you created some magic device like a sail which wound up a spring or something? Okay, a bigger sail would perhaps wind up the spring more quickly, but you'd have to push harder to overcome the wind resistance created by the larger sail, so you'd still be creating an energy deficit system where you'd put more in that you got out.

I've been a cyclist since about 1972 and have been riding all sorts of things, including about 20 years on recumbent bikes and trikes.

It isn't really "wind" that you're feeling, because mostly the breeze is actually caused by you supplying energy yourself to move through mostly still air, and your body is actually creating drag (wasting your energy). You'll have turbulence behind you, again wasting energy.

Perhaps an analogy. If you come to the bottom of a big hill, and you sweat and strain your way up to the top, you get over the crest, and there's a descent which takes you back to the same level again. Now you can coast down the hill (possibly at a very high speed) but this isn't "free" energy/speed . This is potential energy, which you've expended in pedalling up the other side. Same with the wind.

Above a few km/h increasing amounts of the rider's energy is spent overcoming wind resistance. So I'd be looking at instead of capturing the wind, try and reduce the drag I mentioned.

How can one do it?

Well, this link will you an idea of the lengths you'll have to go to. Not very practical.

http://www.recumbents.com/WISIL/speedruns2000/worlds-fastest-bicycle-2000.htm

(Currently the fastest bicycle is over 80 mph)

Many people have tried to harness what they think is "free" energy, but they're up against the fact that the sheer efficiency of the bicycle means that it's VERY easy to detract from that and just wind up going more slowly and carrying more weight.

Ah, well.

But that ain't the end.

If you have a look here,

http://blog.wired.com/cars/2008/09/solar-trikey-ma.html#more

You'll see how I addressed the problem of "free" energy. Or natural. Solar power.

I think you'd probably find research in this area far more productive.

Perhaps more expensive in the short run, but when you take it over time, I think you'll win out.

Good luck, and keep looking. You may find something that the rest of have missed.

Joe

PS Read through the comments in the blog, because I expand on a couple of issues.

J

[Michael Fournier]

What I meant was, is it possible to harness the potential energy of the wind wizzing past you, ( mounted pinwheels, etc. ) convert the energy into electricity, and store it for later use such as in a battery.

Thanks!:)

[Joe Blake]

The amount of energy that you'd harvest that way would be fairly minute.

What would you be using it for?

I doubt whether anything you could gather off the bike would do more than light a small LED.

You could possibly scrounge around and get hold of some old "bottle generators" and make up a wind turbine from them. Maybe a 12 volt car fan could supply you a fan blade you could adapt for a turbine.

This link shows this bloke with a wind turbine of his bicycle (he rides 15-20 miles) which will half recharge his mobile phone.

http://www.treehugger.com/files/2007/10/hymini_windpowe.php

These photos show my bicycle powered generator which is barely enough power to run a small TV and digital receiver as long as I keep pedalling. (You can see the 2x12 volt batteries on the floor just behind the front wheel.)

http://i82.photobucket.com/albums/j245/saxeharp/gen02.jpg

http://i82.photobucket.com/albums/j245/saxeharp/gen01.jpg

Joe

[Michael Fournier]

That gadget in the link is exactly what I wanted to engineer. I'm very pleased at how compact it is as well. Excellent, thanks man.

I like that bike generator. Is there a way to store the power after you make it?

[Joe Blake]

This link is for the generator.

http://www.windstreampower.com/Bike_Power_Generator.php

There you'll also find some generators which don't need a bicycle but can be hand or foot cranked.

The power generated is stored in 2x12 volt batteries (the blue and white cubes just behind the front wheel on the floor). I can then either use the 12 volts directly to power some appropriate gadgets (24 hour LED lighting, computer, radio, etc) or a small 300 watt inverter to run the TV and digital receiver.

I like watching my tapes of the Tours de France while I'm pedalling, but I can't consistently generate sufficient power (100+ watts ) to run BOTH the VCR/DVD and TV while I'm watching. However, the TV requires less than 70 watts, so that's a target I can meet for a sufficiently long time to be possible. Over the short term I can possibly generate 150+ watts, but can't maintain it.

As an alternative, I can use the power generated to help charge the batteries on my tricycle (I put the batteries into series to give 24 volts), so in effect I do my electric triking "ahead of time" while watching TV. :bigsmile:

As I mentioned in my blog, when I bought the electric motor one of the options was to have "regenerative braking" whereby if I travel down a hill, the motor can become a generator and partially recharge the batteries, which is probably what you wanted to do initially, I suspect. But there aren't many hills where I live, so it wasn't worthwhile.

Joe