Last summer, a relative was talking to me about all the great resources where I live. We have good wind, plenty of sunlight, and two rivers flowing in the woodland behind our house. That very afternoon, we had a huge storm where the power went out for three days. That got me thinking about somehow putting up a little wind turbine to get some power. This is how I made it. *I am constantly updating this site as the project goes along, so bear with me*
The first step that I had to accomplish was trying to figure out if it was really worth the time and money to put up something to produce power. I measured daily wind speed, looked at weather maps (http://www.awea.org/faq/usresource.html) and just walked around the yard trying to see where the wind blew the best. Stuff you want to consider are the trees, shrubs, physical obsturctions (Houses, sheds, barns, ect.), and birms, which can make the wind go above your wind turbine. I found a little mound that looked good because it had a great view of the front yard, where the wind usually comes from. I deicided that this is where I wanted my turbine.
Before you start grabbing your tool belt and start buying parts, have an idea on how your turbine is going to look, how fast it is going to go, and how much power it is going to make. Since I never really made a turbine before, I decided with making a turbine that would produce enough power to charge a 12V battery (since the wind doesn't blow all the time and I don't want to suddenly lose power), which will be connected to a DC/AC converter. The inverter will turn the power made by the turbine in the battery to 2 standard 120 volt AC house outlets that I can plug appliances into. I may expand or make another turbine in the future, but for now it is so much easier to start small. If you want to make a turbine that produces more power, feel free to use bigger dimensions to fit your needs. You can always add more batteries to make a 24 or 48 volt system instead of a 12 volt system if neccesary. For major systems that will power an entire house, you might want to use a much bigger setup and something much more advanced that I have here. I spent a while drawing sketches, despite my somewhat average art skills. That helps cover obvious problems. I also did some CAD work, but that really isn't neccesary.
Just about the hardest step in the project is trying to find a generator for your wind turbine to turn. Most people (including me) use DC motors. They have to have permanet magnets, or PM, or else they won't produce power. You want to get a motor that has a low RPM, but high voltage. I know it's an odd cobination, but basically a motor rated for 2000 RPM at 24 volts won't make at least 12 volts until it is spinning at least 1000 rpm, when a turbine will only go about 300 rpm. You want something like 30 volts at 500 RMP I have spent many hours searching the internet, and motors that meet these specifications are hard to come by. Check places lile Ebay and Craigslist first, because new stuff is coming up all the time. A lot of people want to use Ametek motors for their turbines, but they are even rarer. Other brands will work just as good. I got a Dayton 4Z537 that makes 90VDC (volts DC) at roughly 32-40 RPM. (Shown below) If you really don't want to use a dc motor, a 3-phase alternator will work just as good. I'm not currently very experienced with them here, so be sure to check out otherpower.com for other information about them.
DON'T get a gear motor unless it's really worth it. The motor I bought was a gear motor, but it was too hard to turn by hand, more or less blades by the wind. I later adjusted the gears in a way it can turn that I will discuss further down. The motor/generator is one of the most important components in a wind turbine sytstem. It determines the size of the blades, the size ofthe mount and tower, ect. Be sure to pick a good one when shopping.
The blades are by far second on the hardest things to do. I've seen many forums on how big to make blades, what to make them out of, ect. I found out that the easiest way to make blades is using PVC pipe cut into airfoils. This looked promising because they cannot bend, water can easily slide off them, and they are also durable. I had a couple of mishaps, but I decided that the best way to make the blades is to cut a slit halfway down (mostly for asthetics and making it lighter). I made my blades 2 feet in diameter. I also made a 4-foot diameter one in case I need the bigger size, but I haven't used them yet. As you can see, they are on a weak looking piece of wood, but I later added a metal plate from the bottom of a coffee tin. Be aware that making blades take an awful long time, so make sure you can work for at least 4 hours on them. In the end, I decided to put some duct tape on the edge of the blade that cuts into the wind. It's a lot easier than sanding or filing it, and it's downright quicker. For the hub, I got an old piece of round wood, but I would recommend using the bottom of an old coffee container. I later put that on along with a rubber reinforcment. I'll hopefully make a new page for pictures and videos soon.
One design I found that doesn't work well is the one below. It is too flimsy and bends in the wind so much there really isn't any torque. Make sure to have a strong centerpoint, and be extra careful where the blades connect to the hub because this is a really weak spot. A great way to check how your blades work is to put a bolt into your drill and then take it ouside. My blades easily spun up in a slight breeze and stayed pretty consistent afterward.
After much testing, I have decided to make the blades from wood instead. One PVC blade has already broken during a windstorm while I was testing it with a table outside. The blades also need an extreme amount of wind to properly get going once they have a load (the generator). When they do get going, they rarely exceed 100 RPM, when my generator needs 98 RPM (after gear modification) to start making useful power (12V and up). I will explain more about the blades later after I get some pictures, but for now I'll just talk about it. The blades are made from pine wood that is 3 feet instead of 2 feet like the PVC. They are actually more than 3 times as big as the previous blades. Since these blades are so much bigger, they should be able to start in almost no wind and travel pretty fast (they are extremely light blades).
PVC testing and results
I tested this wind turbine on a small table which I set outside on a windy day. These are the results of the small PVC blades, not the new wood blades. For testing I had a volt meter to record the voltage and a small radio in case I needed a load.While I was testing, the sky started to turn threatening. Pretty soon, we were getting wind gusts all the way to 30mph! I tried to use the DC load to slow the turbine dzown, but I didn't have any luck. Finally, I just tried shorting out the turbine. It seemed to slow it down until the gear started slipping on the hose and the blades decided to start right back up! By then, I just wanted to get it to stop so I don't (literally) shoot a blade at something (or someone) at the speed of a bullet! I ended up making a huge amount of friction on the jack shaft, and that seemed to slow it to the point that I could jam a screwdriver between the blades and hold them still. Won't make that mistake again. Now I am considering a furling system to try and prevent this thing from ripping itself apart from the inside out. While I was taking it in, our decorative wind mill 7 feet high fell down, and bent a few blades (it has twelve if you were wondering), and also beat up the tail. I did find a way to use it's lattice-style tower as our "Test tower" before it goes up onto 30 feet. It also got me thinking of somehow adding a furling system so I don't ruin this turbine in storms. Of course, the wood blades will probably have similar problems that I hope to fix. One major problem is that the blades overpower the alternator, so if I were to short it out, I have to potential risk of burning out the copper coil inside the generator with way too much heat, which means that the motor is ruined.
The motor and fin will need something to mount on. I've seen complicated mounts with computer-controlled turning for turning exactly into the wind, but for this basic project, a simple fin will do the trick. I found an old piece of scrap wood lying around, and I figured that should work. I ended up cutting two other pieces of wood that squished the fin, and then I put a screw holding it in. I would suggest using metal or something stronger than wood. The fin is a little flimsy, so I am prepared for it to break eventually. It might be good if it were to break in extremely high winds so that the rest of the turbine will turn out of the wind and hopefully last longer. Much drilling, sawing, and measuring later, I had my mount.
A word of advice is to maybe make the fin a little bigger. This one is all right, but it's not as good as I hoped. I might unscrew it and make a bigger one in the future. Be sure to make the mount big enough for your motor. I found out that the motor I bought needed some work. I bought a gear motor, and therefore had to take apart the gearbox and mess with some of the components. If you made the mistake of getting a gear motor, my advice would to either return it or sell it and get another one, or, if your a hands-on person, get your hands dirty and take out the gears one by one until you get the torque you want. I later made a wood cover that I screwed into the mounting holes to hold the gears in.
Sorry about the fuzzy image.
Here's where we really start digging into the middle of things. The first connection I had to make was conencting the motor's gear to the blades. This is really hard, because you must prevent the blades from sliding in (Tower strike, where the blades hit the tower and ends your turbine's life in a catastrophic failure that could also kill someone else), and even worse, when the blades and hub together start rocketing in any direction, which can hit people, buildings, animals, ect. Let me just say up front that I don't want a 300-RPM spinning disk rocketing towards me or the house. A relative in the project suggested that I use a bearing that will take some of the stress off the motor. That turned out to be a great idea. We drilled two holes in two blocks of wood, and then ran a long screw through it along with some bearings. This way, the entire motor-housing will be in a weather-prood enclosure. I haven't yet found a hose that will connect the end of that screw to the motor, but I'll hopefully find a clamp and then connect that soon.
I finally found a hose that fits, and I decided to use a hose clamp to keep it on the generator. I used another clamp for keeping it from slipping on the screw. It worked pretty well. I decided on cutting the hose down as much as I could, because with it longer it tends to "Wind up", and so the blades get harder to turn. Then it suddenly has enough force to start the generator and requires the normal torque again. With it shorter it no longer has that tendancy to wind up.
While I was building, I also made a new hub. This one is more precise than the previous one, and is made of steel. From just looking at it you couldn't tell if it was off. The blue stuff is this stuff that allows us to make marks on the steel. If you look closely, you can sort of see a thin ring where I used a compass.
As soon as I find the proper fitting hose and clamp, I plan to take it outside on a ladder for it's first test to get an estimate on power production, and to see just how well it all holds together. I really don't want any vibrating, because I have heard as such a thing where the extreme vibrating will slowly but surely take out the screws, and then can easily disassemble the entire mount and send everything flying in just a strong wind.
While I was working on the mount system, I was also considering how I was going to get this system up into the wind. I saw people using pieces of conduit for the tower, but I thought that it would bend a lot. Besides, I didn't want a bunch of guy wires everywhere because that could be dangerous for dirt bikes, skiing, ect. I thought about using something like a flagpole, They're pretty cheap, don't need guy wires, and are reliable. Most models are also telescoping, so it will be pretty easy to repair and maintain the blades, generator, and all the bearings and stuff. I thought about also how high I wanted it. I really wanted it where the wind was really going to blow, and not where there was just a slight breeze. However, I didn't need it 80 feet up in a jetstream. After some more research, I decided that anywhere between 20 and 30 feet should suffice. I also used a tall piece of conduit and strapped a flag on the top so I could see how fast the wind was. I also tried my blades out this way. I decided on later on buying a 16-foot flagpole for about 30 bucks, and then strap some conduit to get it to at least 20 feet. I may do that or even cut down a tree in the backyard and shave the branches off until I just have a trunk, and then use that. I also was thinking about how to make the mount turn easily into the wind, without winding up the wires from the generator. I think that if I put a bearing on the bottom of the mount that slid onto the conduit, it might just work.