Introduction: How I Built an Electricity Producing Wind Turbine
One thing I noticed right away about my property is that most of the time, the wind is blowing. Almost from the moment I bought it, I had the idea of putting up a wind turbine and making some electricity, and later adding some solar panels. This is the story of how I did it. Not with an expensive, store-bought turbine, but with a home-built one that cost hardly anything. If you have some fabricating skills and some electronic know-how, you can build one too.
More details on this project and my other alternative energy projects including my home-built solar panels, and my home-built biomass gasifier can be found on my web site.
Step 1: Acquiring a Generator
I started by Googling for information on home-built wind turbines. There are a lot of them out there in an amazing variety of designs and complexities. All of them had five things in common though:
1. A generator
2. Blades
3. A mounting that keeps it turned into the wind
4. A tower to get it up into the wind
5. Batteries and an electronic control system
I reduced the project to just five little systems. If attacked one at a time, the project didn't seem too terribly difficult. I decided to start with the generator. My online research showed that a lot of people were building their own generators. That seemed a bit too complicated, at least for a first effort. Others were using surplus permanent magnet DC motors as generators in their projects. This looked like a simpler way to go. So I began looking into what motors were best for the job.
A lot of people seemed to like to use old computer tape drive motors (surplus relics from the days when computers had big reel to reel tape drives). The best apparently are a couple of models of motor made by Ametek. The best motor made by Ametek is a 99 volt DC motor that works great as a generator. Unfortunately, they are almost impossible to locate these days. There are a lot of other Ametek motors around though. A couple of their other models make decent generators and can still be found on places like Ebay. This web site talks about the virtues and vices of various Ametek motors when used as generators. http://www.tlgwindpower.com/ametek.htm
I managed to score one of the good 30 volt Ametek motors off of Ebay for only $26. They don't go that cheap these days. People are catching on to the fact that they make great wind generators. Other brands will work, so don't fret about the price Ameteks are going for. Shop wisely. Anyway, The motor I got was in good shape and worked great. Even just giving the shaft a quick turn with my fingers would light a 12 volt bulb quite brightly. I gave it a real test by chucking it up in my drill press and connecting it to a dummy load. It works great as a generator, putting out easily a couple hundred Watts with this setup. I knew then that if I could make a decent set of blades to drive it, it would produce plenty of power.
There is more information on how to choose a motor for use as a generator on my web site at http://www.mdpub.com/Wind_Turbine/
Step 2: Making the Blades
Blades and a hub to connect them to were the next order of business. More online research ensued. A lot of people made their own blades by carving them out of wood. That looked like an outrageous amount of work to me. I found that other people were making blades by cutting sections out of PVC pipe and shaping them into airfoils. That looked a lot more promising to me. This web site tells you how to make a set of blades for a small wind turbine using PVC pipe.
http://www.yourgreendream.com/diy_pvc_blades.php
I followed their general recipe. I did things a little differently though. I used black ABS pipe since my local homecenter store just happened to have pre-cut lengths of it. I used 6 inch pipe instead of 4 inch and 24 inches long instead of 19 5/8. I started by quartering a 24 inch long piece of pipe around its circumference and cutting it lengthwise into four pieces. Then I cut out one blade, and used it as a template for cutting out the others. That left me with 4 blades (3 plus one spare).
I then did a little extra smoothing and shaping using my belt sander and palm sander on the cut edges to try to make them into better airfoils. I don't know if it's really much of an improvement, but it didn't seem to hurt, and the blades look really good (if I do say so myself).
Step 3: Building the Hub
Next I needed a hub to bolt the blades to and attach to the motor. Rummaging around in my workshop, I found a toothed pulley that fit on the motor shaft, but was a little too small in diameter to bolt the blades onto. I also found a scrap disk of Aluminum 5 inches in diameter and 1/4 inch thick that I could bolt the blades onto, but wouldn't attach to the motor shaft. The simple solution of course was to bolt these two pieces together to make the hub. Much drilling, tapping and bolting later, I had a hub.
Step 4: Building the Turbine Mounting
Next I needed a mounting for the turbine. Keeping it simple, I opted to just strap the motor to a piece of 2 X 4 wood. The correct length of the wood was computed by the highly scientific method of picking the best looking piece of scrap 2 X 4 off my scrap wood pile and going with however long it was. I also cut a piece of 4 inch diameter PVC pipe to make a shield to go over the motor and protect it from the weather. For a tail to keep it turned into the wind, I again just used a piece of heavy sheet Aluminum I happened to have laying around. I was worried that it wouldn't be a big enough tail, but it seems to work just fine. The turbine snaps right around into the wind every time it changes direction. I have added a few dimensions to the picture. I doubt any of these measurements is critical though.
Next I had to begin thinking about some sort of tower and some sort of bearing that would allow the head to freely turn into the wind. I spent a lot of time in my local homecenter stores (Lowes and Home Depot) brainstorming. Finally, I came up with a solution that seems to work well. While brainstorming, I noticed that 1 inch diameter iron pipe is a good slip-fit inside 1 1/4 inch diameter steel EMT electrical conduit. I could use a long piece of 1 1/4 inch conduit as my tower and 1 inch pipe fittings at either end. For the head unit I attached a 1 inch iron floor flange centered 7 1/2 inches back from the generator end of the 2X4, and screwed a 10 inch long iron pipe nipple into it. The nipple would slip into the top of the piece of conduit I'd use as a tower and form a nice bearing. Wires from the generator would pass through a hole drilled in the 2X4 down the center of the pipe/conduit unit and exit at the base of the tower. Brilliant! (if I do say so myself)
Step 5: Build the Tower Base
For the tower base, I started by cutting a 2 foot diameter disk out of plywood. I made a U shaped assembly out of 1 inch pipe fittings. In the middle of that assembly I put a 1 1/4 inch Tee. The Tee is free to turn around the 1 inch pipe and forms a hinge that allows me to raise and lower the tower. I then added a close nipple, a 1 1/4 to 1 reducing fitting, and a 12 inch nipple. Later I added a 1 inch Tee between the reducer and the 12 inch nipple so there would be a place for the wires to exit the pipe. This is shown in a photo further down the page. I also later drilled holes in the wooden disk to allow me to use steel stakes to lock it in place on the ground.
The second photo shows the head and base together. You can begin to see how it will go together. Imagine a 10 foot long piece of steel conduit connecting the two pieces. Since I was building this thing in Florida, but was going to use it in Arizona, I decided to hold off on purchasing the 10 foot piece of conduit until I got to Arizona. That meant the wind turbine would never be fully assembled and not get a proper test until I was ready to put it up in the field. That was a little scary because I wouldn't know if the thing actually worked until I tried it in Arizona.
Step 6: Paint All the Wood Parts
Next, I painted all the wooden parts with a couple of coats of white latex paint I had leftover from another project. I wanted to protect the wood from the weather. This photo also shows the lead counterweight I added to the left side of the 2X4 under the tail to balance the head.
Step 7: The Finished Head of the Wind Turbine
This photo shows the finished head unit with the blades attached. Is that a thing of beauty or what? It almost looks like I know what I'm doing.
I never got a chance to properly test the unit before heading to Arizona. One windy day though, I did take the head outside and hold it high up in the air above my head into the wind just to see if the blades would spin it as well as I had hoped. Spin it they did. In a matter of a few seconds it spun up to a truly scary speed (no load on the generator), and I found myself holding onto a giant, spinning, whirligig of death, with no idea how to put it down without getting myself chopped to bits. Fortunately, I did eventually manage to turn it out of the wind and slow it down to a non-lethal speed. I won't make that mistake again.
Step 8: Build the Charge Controller
Now That I had all the mechanical parts sorted out, it was time to turn toward the electronic end of the project. A wind power system consists of the wind turbine, one or more batteries to store power produced by the turbine, a blocking diode to prevent power from the batteries being wasted spinning the motor/generator, a secondary load to dump power from the turbine into when the batteries are fully charged, and a charge controller to run everything.
There are lots of controllers for solar and wind power systems. Anyplace that sells alternative energy stuff will have them. There are also always lots of them for sale on Ebay . I decided to try building my own though. So it was back to Googling for information on wind turbine charge controllers. I found a lot of information, including some complete schematics, which was quite nice, and made building my own unit very easy. I based my unit on the schematic of the one found on this web site:
http://www.fieldlines.com/story/2004/9/20/0406/27488
That web site goes into a lot of detail about the controller, so I'm only going to talk about it in fairly general terms here. Again, while I followed their general recipe, I did do some things differently. Being an avid electronics tinkerer from an early age, I have a huge stock of electronic components already on hand, so I had to buy very little to complete the controller. I substituted different components for some parts and reworked the circuit a little just so I could use parts I already had on hand. That way I had to buy almost nothing to build the controller. The only part I had to buy was the relay. I built my prototype charge controller by bolting all the pieces to a piece of plywood, as seen in the first photo below. I would rebuild it in a weatherproof enclosure later.
Whether you build your own, or buy one, you will need some sort of controller for your wind turbine. The general principal behind the controller is that it monitors the voltage of the battery(s) in your system and either sends power from the turbine into the batteries to recharge them, or dumps the power from the turbine into a secondary load if the batteries are fully charged (to prevent over-charging and destroying the batteries). The schematic and write-up on the above web page does a good job of explaining it. Much more information on building the charge controller, including larger and easier to read schematics, can be found on my web site at http://www.mdpub.com/Wind_Turbine/index.html
In operation, the wind turbine is connected to the controller. Lines then run from the controller to the battery. All loads are taken directly from the battery. If the battery voltage drops below 11.9 volts, the controller switches the turbine power to charging the battery. If the battery voltage rises to 14 volts, the controller switches to dumping the turbine power into the dummy load. There are trimpots to adjust the voltage levels at which the controller toggles back and forth between the two states. I chose 11.9V for the discharge point and 14V for the fully charged point based on advice from lots of different web sites on the subject of properly charging lead acid batteries. The sites all recommended slightly different voltages. I sort of averaged them and came up with my numbers. When the battery voltage is between 11.9V and 14.8V, the system can be switched between either charging or dumping. A pair of push buttons allow me to switch between states anytime, for testing purposes. Normally the system runs automatically. When charging the battery, the yellow LED is lit. When the battery is charged and power is being dumped to the the dummy load, the green LED is lit. This gives me some minimal feedback on what is going on with the system. I also use my multimeter to measure both battery voltage, and turbine output voltage. I will probably eventually add either panel meters, or automotive-style voltage and charge/discharge meters to the system. I'll do that once I have it in some sort of enclosure.
I used my variable voltage bench power supply to simulate a battery in various states of charge and discharge to test and tune the controller. I could set the voltage of the power supply to 11.9V and set the trimpot for the low voltage trip point. Then I could crank the voltage up to 14V and set the trimpot for the high voltage trimpot. I had to get it set before I took it into the field because I'd have no way to tune it up out there.
I have found out the hard way that it is important with this controller design to connect the battery first, then connect the wind turbine and/or solar panels. If you connect the wind turbine first, the wild voltage swings coming from the turbine won't be smoothed out by the load of the battery, the controller will behave erratically, the relay will click away wildly, and voltage spikes could destroy the ICs. So always connect to the battery(s) first, then connect the wind turbine. Also, make sure you disconnect the wind turbine first when taking the system apart. Disconnect the battery(s) last.
Step 9: Erect the Tower
At last, all parts of the project were complete. It was all done only a week before my vacation arrived. That was cutting it close. I disassembled the turbine and carefully packed the parts and the tools I'd need to assemble it for their trip across the country. Then I once again I drove out to my remote property in Arizona for a week of off-grid relaxation, but this time with hopes of having some actual electricity on the site.
The first order of business was setting up and bracing the tower. After arriving at my property and unloading my van, I drove to the nearest Home Depot (about 60 miles one way) and bought the 10 foot long piece of 1 1/4 inch conduit I needed for the tower. Once I had it, assembly went quickly. I used nylon rope to anchor the pole to four big wooden stakes driven in the ground. Turnbuckles on the lower ends of each guy-line allowed my to plumb up the tower. By releasing the line from either stake in line with the hinge at the base, I could raise and lower the tower easily. Eventually the nylon line and wooden stakes will be replaced with steel stakes and steel cables. For testing though, this arrangement worked fine.
The second photo shows a closeup of how the guy-lines attach near the top of the tower. I used chain-link fence brackets as tie points for my guy-lines. The fence brackets don't quite clamp down tightly on the conduit which is smaller in diameter than the fence posts they are normally used with. So there is a steel hose clamp at either end of the stack of brackets to keep them in place.
The third photo shows the base of the tower, staked to the ground, and with the wire from the wind turbine exiting from the Tee below the conduit tower. I used an old orange extension cord with a broken plug to connect between the turbine and the controller. I simply cut both ends off and put on spade lugs. Threading the wire through the tower turned out to be easy. It was a cold morning and the cord was very stiff. I was able to just push it through the length of the conduit tower. on a warmer day I probably would have had to use a fishtape or string line to pull the cord through the conduit. I got lucky.
Step 10: Erect the Wind Turbine
The first photo shows the turbine head installed on top of the tower. I greased up the pipe on the bottom of the head and slid it into the top of the conduit. It made a great bearing, just as I'd planned. Sometimes I even amaze myself.
Too bad there was nobody around to get an Iwo Jima Flag Raising type picture of me raising the tower up with the head installed.
The second photo shows the wind turbine fully assembled. Now I'm just waiting for the wind to blow. Wouldn't you know it, it was dead calm that morning. It was the first calm day I had ever seen out there. The wind had always been blowing every other time I had been there. Well, nothing to do but wait.
Finally! The wind was up and the turbine was spinning, and the lovely electricity is is starting to be produced.
Step 11: Connect the Electronics
The first photo below shows the electronics setup. The battery, inverter, meter and prototype charge controller are all sitting on a plywood board on top of a blue plastic tub. I plug a long extension cord into the inverter and run power back to my campsite. Lots more information of the electronics set-up can be found on my web site at http://www.mdpub.com/Wind_Turbine/
Once the wind starts blowing, the turbine head snaps around into it and begins spinning up. It spins up quickly until the output voltage exceeds the battery voltage plus the blocking diode drop (around 13.2 volts, depending on the state of the battery charge). it is really running without a load until that point. Once the that voltage is exceeded, the turbine suddenly has a load as it begins dumping power into the battery. Once under load, the RPMs only slightly increase as the wind speed increases. More wind means more current into the battery which means more load on the generator. So the system is pretty much self-governing. I saw no signs of over-reving. Of course in storm-force winds, all bets are off.
Switching the controller to dump power into the dummy load did a good job of braking the turbine and slowing it way down even in stronger gusts. Actually shorting the turbine output is an even better brake. It brings the turbine to a halt right now, even in strong winds. Shorting the output is how I made the turbine safe to raise and lower, so I wouldn't get sliced and diced by the spinning blades. Warning though, the whole head assembly can still swing around and crack you hard on the noggin if the wind changes direction while you are working on these things. So be careful out there.
Step 12: Enjoy Having Power in the Middle of Nowhere
How sweet it is! I have electricity! Here I have my laptop computer set up and plugged into the power provided by the inverter, which in turn is powered by the wind turbine. I normally only have about two hours of battery life on my laptop. So I don't get to use it much while I'm camping. It comes in handy though for downloading photos out of my camera when its memory card gets full, making notes on projects like this one, working on the next great American novel, or just watching DVD movies. Now I have no battery life problems, at least as long as the wind blows. Besides the laptop, I can also now recharge all my other battery powered equipment like my cell phone, my camera, my electric shaver, my air mattress pump, etc. Life used to get real primitive on previous camping trips when the batteries in all my electronic stuff ran down.
I used the wind turbine to power my new popup trailer on a later vacation. The strong spring winds kept the wind turbine spinning all day every day and most of the nights too while I was in Arizona. The turbine provided enough power for the interior 12V lighting and enough 120V AC at the power outlets to keep my battery charger, electric shaver, and mini vacuum cleaner (camping is messy) all charged up and running. My girlfriend complained about it not having enough power to run her blow-dryer though.
Step 13: How Much Did It Cost?
Part Origin Cost Motor/Generator Ebay $26.00 Misc. pipe fittings Homecenter Store $41.49 Pipe for blades Homecenter Store $12.84 Misc hardware Homecenter Store $8.00 Conduit Homecenter Store $19.95 Wood & Aluminum Scrap Pile $0.00 Power Cable Old extension cord $0.00 Rope & Turnbuckles Homecenter Store $18.47 Electronic Parts Already on hand $0.00 Relay Auto Parts Store $13.87 Battery Borrowed from my UPS $0.00 Inverter Already on hand $0.00 Paint Already on hand $0.00 Total $140.62Not too bad. I doubt I could buy a commercially made turbine with a comparable power output, plus a commercially made charge controller, plus a commercially made tower for less than $750-$1000.
More details on this project and my other alternative energy projects including my home-built solar panels, and my home-built biomass gasifier can be found on my web site.
Step 14: Update
I have completed the rebuild of the charge controller. It is now in a semi-weatherproof enclosure and I have also added a built in voltage meter. Both were bought cheap on Ebay. I have also added a few new features. The unit now has provisions for power inputs from multiple sources. It also has built-in fused 12V power distribution for three external loads.
The second photo shows the inside of the charge controller. I basically just transferred everything that I originally had bolted onto the plywood board in the prototype into this box. I added an automotive illuminated voltage gage and fuses for 3 external 12V loads. I used heavy gage wire to try to reduce losses due to wire resistance. Every watt counts when you are living off-grid.
The third image is the schematic for the new charge controller. It is pretty much the same as the old one above, except for the addition of the Volt meter and extra fuse blocks for the external loads. A larger, easier to read version of the schematic, and more information on the new charge controller can be found on my web site at http://www.mdpub.com/Wind_Turbine/
The fourth photo is a block diagram of the whole power system. Note that I only have one solar panel built right now. I just haven't had the time to complete the second one. Please visit my home-built solar panel page at http://www.mdpub.com/SolarPanel/ for more information on home-built solar panels.
Step 15: Update 2
Once again I stayed on my remote property during my recent vacation in Arizona. This time I had both my home-built wind turbine and my home-built solar panel with me. Working together, they provided plenty of power for my (admittedly minimal) electricity needs.
The second photo shows the the new charge controller unit. The wires on the left side are coming from the wind turbine and solar panel. The wires on the right side are going to the battery bank and dummy load. I cut up an old heavy-duty 100 ft. extension cord to make cables to connect wind turbine and solar panel to the charge controller. The cable to the wind turbine is about 75 feet long and the cable to the solar panel is about 25 feet long. The battery bank I am currently using consists of 11 sealed lead-acid 12V batteries of 8 Amp-Hour capacity connected in parallel. That gives me 88 Amp-Hours of storage capacity, which is plenty for camping. As long as it is sunny and windy, (nearly every day is sunny and windy on my property), the wind turbine and solar panel keep the batteries well charged.
More details on this project and my other alternative energy projects including my home-built solar panels, and my home-built biomass gasifier can be found on my web site.
