|New Nerdy Theory: Wind Power|
|Written by Mahoney|
|Tuesday, 25 October 2011 12:18|
Over the course of the day while I sit at work my mind wonders, like any sane person's mind would, and I think up of some really cool hacks that I would like to build. There are a number of reasons that I don't get around to building them, but mostly it's a a matter of money and time. Parts cost money. And assembling those parts takes time. Between kids, wife, dog, and TF2 I don't have much of either.
But just because we can't directly build our thoughts doesn't mean we should rule out the idea of drafting our thoughts on paper... or digital files. I've decided I'm going to at least draft down the theory of what I would do in some projects and leave it up to public debate on how viable of a solution it all is.
First on deck from my mind is an idea to hack parts together and create a high efficiency source of wind power.
DIY wind power is nothing new. A quick google search will yield thousands of results. If you point your browser over to Instructables, a DIY community how to website, you'll find loads. And don't forget to check Make Magazine, but, honestly, if you're reading this then you already know about those sites. The idea I have for my wind turbine varies from some of the other plans out there by including the gears, chain, and rear wheel of a bicycle to increase the efficiency of the wind turbine.
BLADES: Essential to every wind turbine, the blades are the start of your path to efficiency. My plan is to shape long blades using pink insulating foam board and then seal them in a wrapping of fiberglass cloth. The actual shape would be something akin to a wing from a plane that is in "full flaps" configuration.
Flaps on an airplane are used to increase the area of the wing during take off and landing. If you've ever flown on a wing seat in an airplane you may have seen the flaps move. It looks like the rear part of the wing extends out and downward. This greater area increases lift at slower speeds. They're not used in flight because it creates drag, but that's not what I'm worried about with this project. I want the maximum amount of lift possible to get a high speed rotation from the turbine.
I am, however, stuck on the idea of the number of blades to use. As the number of blades goes up the return on efficiency diminishes, and noise from the wing tips increases. But, recent developments have shown a wide variety of designs that take the standard 3 blade design and rework it entirely. While these innovations are unique and promising their reliance on ducting makes it a little unfeasible for my one man garage workshop to handle. So I'll be sticking with a standard 3 blade design.
THE GENERATOR: The wheel has been the single greatest piece of technology man has ever invented. Without it, nothing of what we know today would be possible. All the iDevices in the world mean nothing without power, and that power comes from spinning the wheel. In the case of power generation the wheel is a series of magnets spinning near a wire coil. The magnetic filed created frees up some electrons and now we have electricity. In this build, this is where the bicycle parts come in.
My blades on their hub, would be attached to the pedal section of a bicycle. The frame of the bike would be stripped away, leaving only the parts that I absolutely need. As the blades turn the chain would turn the rear wheel area of the bike. The rear wheel would have the tire, tube, and most of the spokes stripped away in order to reduce mass and the overall moment of inertia. The rim would be flattened like a pancake to make a fin like structure to which I would attach some super strong neodymium magnets using a two part epoxy.
A fixed structure attached to either side would house the required wire coils and send power off to contoller monitors and batteries.
The increase in diameter of the magnetic wheel means more speed, which translates into a greater amount of power being produced, but that's not the only increase in efficiency. The chain drive of the bicycle acts like a transmission. Now we just need to control it.
THE TRANSMISSION: When you are riding a bicycle you cycle the gears to increase the efficiency of your pedaling. When riding on level terrain you would use the highest gear ration possible to move farther with every pedal. That ratio being the largest sprocket on the pedals, and the smallest sprocket on the rear wheel. If the pedal sprocket has a diameter of 12 inches, and the rear wheel sprocket a diameter of 3 inches, then the rear wheel is making 4 revolutions for every one revolution of the pedals. So your output is four time greater than your input.
But if you do this uphill it is very hard to maintain. So you reduce the gear ration in the opposite direction; the largest sprocket in back and the smallest sprocket at the pedals. In the case of our wind turbine the higher the wind speed, we want a higher gear ratio and the opposite for a lower wind speed.
Manipulating the gears is where the theory comes in. By using an optical sensor and arduino we could determine the speed of the wheel. This information could be used to determine a speed point at which the gears should be advanced. The Arduino could trigger a servo that actuates the gear adjusting cables. As the speed of the wheel decreases the gear ratio could be lowered. The Arduino would know what position the gears are in by the use of micro switches being placed in select areas in line with the servo.
This whole system would be powered by leeching energy directly from the generator (after rectifying and regulating) so that it is a self contained power system that is only turned on when needed, in this case, when the wind blows.
IN CONCLUSION: This idea is a slight upgrade from a standard DIY generator in that increases the output of the generator. Most DIY turbines attach the magnets to the hub of the blades and do not gain as much speed as this system would produce. The inclusion of ducting would greatly increase the potential output, but may be out of reach of the average garage workshop.