This article is an update of DanF's original article, still found at the bottom of this page. This update was originally printed in the November 2005 issue of the Energy Self Sufficiency Newsletter.
From Anita: Dear Mr. Windbag: I’m a high-school student and have a class assignment on renewable energy. We have all semester to build and test a project thatsaves energy or makes energy, and we have to document our results. I’m really interested in wind power, and I’d like to build small wind turbine that will light up a light bulb. Where do I start?
Wind power is fun to experiment with, and not that difficult or expensive. But you should first have realistic expectations of what kind of result you’ll be able to get with how much work andexpense. Another important aspect of science projects (and required at science fairs) is demonstrating your use and understanding of the Scientific Method of observation, hypothesis, predictions, testing, and conclusion. Hopefully I’ll be able to give you some good background knowledge so you can decide how to proceed with your project.
First, it would be an excellent idea to familiarize yourselfwith how wind turbines extract energy from the wind, and their basic components and how they work together. Take a look at Part 1 of my “Small Wind Turbine Basics article in the ESSN for the math involved – it’s very simple. Familiarize yourself with Ohm’s Law – a Google search will fill you in. There are also excellent introductions to wind power and wind turbine components at Windpower.org – besure to take all their “guided tours”, not just the one for kids.
The two most important design issues you’ll have to decide on are:
* Can your wind turbine fly outside in real wind to test your design and gather data, or does it have to fly inside using wind from an electric fan, such as at a science fair inside a gymnasium?
* Do you only need to show and measure power output on ameter, or does your wind turbine have to do something physical like power a small light bulb or LED, or make a small pump turn?
If fan power must be used, options for your turbine’s power output are more limited. But for younger students, fan power is the best way to go – a very safe, fast and easy way to demonstrate wind power. The safety precautions needed are minimal. Fan power may frequently bethe only option if the turbine must be demonstrated indoors. However, it’s very difficult to do anything with fan power besides making a meter move and measuring the results. Powering light bulbs and LEDs with fan power takes lots of extra complexity and expense – but it can be done.
The “real wind” can be from mounting the turbine outside on a tower, or from mounting it on a vehicle andcollecting data while an adult drives – slowly, on a rural road with little traffic
– and calls out the vehicle’s speed. If real wind can be used for power, more options for experiments are available, but everything must be built better and sturdier.
The problem is that a small, experimental turbine designed to fly and make power efficiently in real wind won’t even start to move with a fan, while asmall turbine that can turn under fan power will quickly blow apart in real wind. Wind made by a fan is very slow and very turbulent, so it doesn’t have much power available in it.
As for choosing your load, whether it’s a light bulb, LED, charging a battery, or some other type of load, it’s simpler to first choose your generator and then decide on a load. Here’s an overview to get you started.DC Hobby Motors
Many people decide to go this route, since a DC motor when driven acts as a generator, and it’s easy – put a rotor on a DC motor, mount it, and let ’er rip! It’s quite suitable for younger students who have not yet learned any more than the basics of electricity in class, and for classes that will not be studying electricity further.
However, the results are usually...