Building A Wind Power Generator In Your Backyard

For many environmental enthusiasts, horizontal-axis wind turbines (HAWTs) — the kind that look like windmills slowly spinning in the distance — are a pretty familiar sight. Unfortunately, there are quite a few caveats that make them harder to adopt despite the fact that harvesting renewable energy sources is more sustainable than relying on natural gas and fuels that can be depleted. Since they face in one axis, they need to be able to track the wind, or else trade off the ability to maximize energy output. In turbulent and gusty conditions, as well, HAWTs face accelerated fatigue when harvesting.

The development of the vertical-axis wind turbine (VAWT) solves several of these issues. In addition, the turbines are typically closer to the ground and the gearbox replacement is simpler and more efficient. Maintenance is more accessible due to the size of the turbines, so no heavy machinery is typically necessary to access crucial components on-site. In addition, the gearbox by nature of its operation takes on less fatigue and is able to function in turbulent winds, which reduces the rate of failure.

For a simple version of a VAWT that you can build yourself, [BlueFlower] has published several mechanical drawings that detail the layout of the design. The wind power generator uses 24 magnets, copper wire fashioned into coils, and a metal plate for the main generator. The coils are arranged in a circular formation on a static plate, while the magnets are equally spaced on a moving circular plate. As the magnets pass over coils, the flux induces a current, which increases as the plates spin faster.

The blades of the generator are made from blue foam with a metal bar running through it for structure. Three of the blades are attached with triangular bars to a central rod, which also holds the spinning magnetic plate.

In [BlueFlower]’s initial trials using the VAWT for charging a battery they were able to generate a max power of 15W on boost mode and 30-70W when charging in PWM mode. Not bad for a home-made wind power generator!

There aren’t only pros to the design, however. While VAWTs may be cheaper, more mobile, and more resistant to wear and tear, there are some design features that prevent the generators from functioning as well as HAWTs at harvesting energy. The blades don’t produce torque at the same time, with some blades simply being pushed along. This produces more drag on the blades when they rotate, limiting the efficiency of the entire system. In addition, higher wind speeds are typically found at higher altitudes, so the VAWTs will perform better if installed on a towering structure. Vibration forces close to the ground can also wear out the bearings, resulting in more maintenance and costs.

 

 

49 thoughts on “Building A Wind Power Generator In Your Backyard

    1. just spent a minute trying to figure out what perpetual motion had to do with vawt. now that I’ve got that straightened out you should know that vawt do have a few positives besides efficiency which hugh mentions in book four of his misnamed hitchhikers guide to wind turbine trilogy.

      1. It’s an obvious jab at people who take the few positives and ignore the motherload of negative points to push some particular solution over another – typical of snake oil salesmen.

        If you examine the efficiency over tip speed ratio (TSR) of different types of turbines, you’ll see that VAWT turbines start to block out really early. That is, they can only utilize a narrow range of wind speeds before they saturate and cannot produce any more power. This means they’re wasting almost all of the incoming wind energy most of the time.

        That, plus the fact that VAWT turbines don’t capture a lot of wind area for the amount of materials and cost you put into them, makes them generally not worth the effort.

        1. The biggest bonus I see is that you don’t need to swing the VAWT to face the wind, it does not care what direction the wind is coming from. Another bonus is the orientation of the generator itself.

          1. The steering problem with HAWT was solved many decades ago with prairie windmills- you just put it on a swivel and put a fin on the back side of that.

          2. In most locations, there’s a dominant wind direction which causes the turbine to swing back and forth on one side. Many times people get away with just leaving a lot of slack in the cable and let it twist – then they come in a year later and un-twist it.

        2. True but this acts like a built in inexpensive safety in case of winds high enough to cause self destruction. Most have a clutch or vain to turn the blades to a point where they’re inefficient, something built in on this one.

    2. Small thinking for small minds. HAWT’s have been in development a long time, and they still breakdown. What’s with that? By now, you should have the engineering down to a fine art. But, they still crash and burn. When VAWT’s have been in development as long, then talk to me about how they compare. When “sweep” is finally determined to be a “non starter” and they start comparing apples to apples, then talk to me. Me, I’m going to reserve judgement for the present time. I think VAWT’s have farther to travel to be “on par” with HAWT’s, but I also believe that with the right “combination” of breakthroughs”, they could surpass HAWT’s. Woops! My bad!

      1. It’s more of a politics thing. Governments are paying subsidies – basically guaranteed prices per MWh sold – for as long as the industry can argue that they need it. So, everyone’s really just dragging their feet so they wouldn’t have to step off the gravy train. The major function of the subsidies is to remove the need to compete, because everyone gets the same prices, so the best and worst designs make no difference. They only have to last as long as the subsidies run, and then you can tear the turbines down and build new ones to reset the clock. Pick the cream off the top.

        VAWTs are a hundred years old thing. The Savonius turbine was invented in 1922. The Darreius in 1926. They have been in development for a long time and many people have tried to make them work – they just aren’t very good.

  1. The point of wind energy isn’t to capture every random gust and turn. That’s a small part of the energy that is available to a wind turbine.

    The power of wind goes up in the cube of wind speed, while the probability of wind speeds at a location is heavily biased on low wind speeds, which means the most energy you will produce happens on the relatively few days with high steady winds, and those days when you’re getting winds from varying directions produce little to no energy because turbulent conditions have low average wind speeds.

    On the average wind farm, you will produce 50% of the energy output in just 15% of the running time. If you run the math, it turns out to be pretty much on/off behavior. You get either nearly the full nameplate capacity, or close to none with the turbines merely turning but not making any power. As a rule of thumb, over the average week, you get 1-2 days of power, and 5-6 days of little to no power.

    The VAWT is able to produce power more steadily largely because it saturates early. It is able to utilize winds in the turbulent condition when the direction changes rapidly, but it is unable to utilize high wind speeds where the vast majority of the available energy is, so it’s really of no advantage at all. It is just worse.

      1. As a tradeoff, you get really low average power output for the cost and size of the device, and it still isn’t steady enough so you could get away with significantly smaller batteries.

        Unless you’re literally at Antarctica, there’s usually no point.

    1. I’ve had a similar experience with photovoltaic panels – it’s either full sunshine and full power, or next to nothing at all other times. And I don’t live in the sun belt, so I get mostly next to nothing. Unfortunately, the cost of PV is such that it isn’t practical to size an array to produce enough power on overcast days.

  2. > It is just worse.

    Does that apply if you’ve only space to build a WT of a similar size close to the ground?

    And if you’re in an area with local obsticles upwind of the local Prevailing wind resulting in 95% turbulent wind flow that also buffers high wind? As in, you’re only going to get low to medium winds of varying directions?

      1. Yeah, the “Urban microturbine” is a horse beaten well past its death. Every now and then someone gets the good idea of “what if we…” and the run the economics, and find out that it would cost 10x the grid price for power before you even count in the labor costs.

    1. Because WordPress switched our comment system over to Jetpack, which requires some scripting/cookies/whatever on your side to function. You are blocking such, and that messes up the comment threading.

      Should they put that burden on you? Nope. Are they doing it? Yup.

  3. I am one of the folks with 55 gallon barrels cut in half and welded together. It gets me enough power where I need it. It cost me nothing and was easy to build and should go almost forever with few issues. Ok, the bike innertube I use as the drive belt to the alternator may croak. I have more.

    I also built a spiral pump to get water out of the creek, and up a hill. I showed it to some of my ivy league friends and they were all pondering it’s low efficiency. They were also all humping water out of their sources with jugs and buckets if their gardens were out of the reach of the hose.

    I have solar in a few places. From 15W running a small pump from my pond to my greenhouse to 150W in one of my out buildings. I think I have a 25W panel in the building I store the lawn tractor in and that keeps the battery topped off in it, and a 50W system in my cabin in the woods. I don’t think any of the panels breaks 20% efficiency. They were inexpensive. That is why I can afford them.

    The thing with free energy is, it is nice to ponder how much more efficient it could be, but really, unless you have something better to do with it, it is all just wasted with nothing. Every one of my little setups saves me a lot of time and bother. Could they be more efficient. Sure. Hell, the best solar cells you can get could be 70% more efficient, but a lot of people are really happy with roofs full of what they have and what they can afford and watching the electrometer spin slower for it.

    1. Your comment deserves my upvote.

      I see a lot of people complaining about using arduinos on everything, about the correct way to do everything, to solder with the left or right hand… It does not matter!

      Unless you NEED the efficiency, it’s not worth optimizing everything to the last atom. The fun is on the build, not on the result (unless you are paid for the result). It works? You are happy? So it’s the right way.

      I have a cubietruck running 24×7 playing downloaded Youtube videos on my TV. My daughter can turn on the TV, watch whatever is streaming at the moment, and shutdown the TV again. The cubie does not care, it keeps playing day and night. I could have used a TV box, a smart TV, a chromecast, and Apple TV… but this works, so I don’t care.

    2. This addresses a problem with most large scale solar power (thermal or PV) installations. They tap the power for operation of the system from the main collection. It would be easier to mount independent collectors to do things like run pumps and power tracking motors. For a large PV array, mount additional cells around each panel, their sole job to provide the power to the motors and electronics for each collector’s sun tracking motion.
      Or use some space along one edge of the array land for collectors dedicated to powering the tracking systems of all the other collectors.

      Got a box of electronics that needs 50 watts to operate? Mount a 75 watt panel right beside it rather than tapping power from the main array.

      Dedicating 100% of the main array’s output to feeding into the power grid, while other systems are served by dedicated collectors, would make design of the main array simpler.

      1. Oh, I don’t think so. What you are suggesting is that if you have 25 devices that need power, then you should have 25 generators, 25 batteries, 25 chargers, and 25 power converters for the devices.

        Yeah, it seems simpler when you have three or four devices, and it actually could make sense for those devices that are either remotely located or need to be portable. But in general, building an optimally sized power generation, storage, and conversion for each device is not a winning strategy.

        1. I don’t believe that is what is being suggested. I’m pretty sure there was no implication of any power storage, no batteries, no chargers, no power converters. Try reading [reg]’s post first, then [Gregg]’s.

      2. >”Got a box of electronics that needs 50 watts to operate? Mount a 75 watt panel right beside it rather than tapping power from the main array.”

        What do you mean, 50 Watts?

        Does it need it all the time, some of the time, or just randomly when the sun happens to shine right on the panel?

        Most modern electronics don’t like to operate in a “brown-out” condition where there’s some voltage and current but not enough to fully power up the device. This stresses their power supply components and usually leads to rapid failure. Other things like DC motors, same thing applies – you have some amount of power but not enough to turn the motor, which basically just heats up the coils and welds the brushes to the commutator. About the only thing that can run properly straight off a solar panel is a resistance heater.

        You need a battery and some smarts between to buffer some energy, and turn the device on and off in a controlled manner, and that means you have to duplicate this system for all the devices.

    3. >”The thing with free energy is…”

      That it’s almost never actually free. People just don’t count how much money, time, gasoline, electricity, tools and materials, they’ve used up in order to make one of their “free power” generators.

      The power may be free to you, as in, if you’ve scrounged up an old barrel and put it spinning on an old wheel hub, but probably the amount of energy you’re ultimately getting out of it doesn’t cover the gas you used when you drove out to the hardware store to get more parts.

      A 15 Watt generator turning constantly produces about 131 kWh a year, which is equivalent to four gallons of gasoline. With these low efficiency devices, it’s ridiculously easy to spend more resources in the form of material and energy, than you’ll ever get back out of it.

      1. Oh gosh, where t start. To the person who said you need storage. No, not in all cases. The solar panel that runs the pump for the greenhouse has no storage. This works out real well. When it is sunny and hot, the plants get a lot of water. On a grey day, not so much. I have had this set up for a season now and it works remarkably well, and I am not humping 5 gallon cans of water from the house or wading out in the pond to fill up gallon jugs. You have to wade way out for it to be over the top of a 5 gallon jug. It is not 100% efficient, but it does exactly what I hoped it would do.

        The panel that keeps the lawn tractor battery topped off, I guess that battery is storage, but I mean, I don’t have a lot of electronics between the two. I do have a battery tender module. I have had that set up for years now and I am still on the same battery in the tractor. Many of my cohorts have the spring ritual of buying a new one. Come spring, I turn the key and mine starts. Again, not near 100% efficient but it does what I want.

        Two of my locations do have storage, and it is far from optimal. One of them has a garden tractor battery. It has been there for years. It also has a 200W inverter board out of an old 5 way Harbor Freight jump pack. This drives two 105W CFL (500W incandescent equivs) in stadium light fixtures that used to hold 750W incandescent bubs. The whole thing is motion sensitive. Back when I built this, LED’s were too expensive. Now I would do it with LED’s, but the fact it, for many years, this system has worked flawlessly. Again, I am happy with it.

        The other location with storage is deep out in the woods. A little two story get away that overlooks the creek. The first floor has a couch and a big window that takes up most of the front wall, and a vent free propane heater. A ladder gets you up to the loft. A single bed is up there. There are LED lights up and down stairs and an old 12V car battery with an inverter will power a notebook and a small stereo overnight. That’s all I wanted. Again I am happy.

        The spiral pump works all the time. In season, I use it to irrigate my mushroom bots. Many people carry them to big watering tanks for a soak, and than re-stack them. For years I had big screw eyes (I got these for a buck a box at the $1 store) in them and would carry them down to the creek and chain them to a tree and soak them. Now I hook the pump to a piece of 1″ well hose with little holes drilled in it and they get soaked in place. At some point if I get a bunch of people here at once, I have an old hot tub I want to carry back there, not to soak my logs in, but to be a nice cold tub for when I get out of my sweat hit that is also out there by the creek. In the winter it is hard climbing down the bank to the creek without slipping. Having a nice cold plunge right next to the sweat would be great. Pump fresh water out of the creek and direct the overflow right on back.

        The wind turbine is a bit of a work in progress. It was going to keep a battery topped off for another motion light, but I am getting a motor home and that will be parked on the far end of the property, the turbine may wind up keeping the house battery topped off in the off season. That is all I am asking for. If I can get the output of an HP battery maintainer but without needing to plug it in. I am pretty sure I can do that. Now I doubt I can power much up full time, but I suspect I will be able to turn the (LED) interior lights on and the radio from time to time, and recover the battery from that.

        BTW, you have to see how I work to understand how inexpensively you can make things. When I say made out of junk, I really mean made out of junk. I rarely hit the hardware store. I do pick things up roadside all the time though. and my friends know I have an affinity for junk.. I take pride in turning out things with budgets of almost nothing. I will admit that I do trade time for $$, but time I have and $$ I don’t.

          1. I agree! I would enjoy reading more of the devices you’ve designed and the manner in which you’ve designed them.

            Personally, I’m starting to look into some emergency power abilities. Being in an area that we sometimes lose power due to storms, my interest is mainly to power lights and fans (for people cooling) with a low-voltage system (12/24 volt). Most 120V power inverters are not very efficient. The question is whether or not the wind-turbine being used to charge the batteries will replenish the charge that the daily discharge depletes or will it be a downhill slide …?

            Peace and blessings.

      2. So true. Even oil is free, but then you need to pay for the ground, pump it out of the ground, transport it, refine it, pay taxes on it all and whatever. Same is true for every type of energy just as a quarter on the ground isnt free money, you got to bend over and pick it up. Likely Bill Gates could not economically justify stopping to bend over to pick up a $100 bill.

  4. I have designed and constructed a small wind generator for household use experimented by running by motor and now trying on wind. Using hawt. What type of blades are best is my present concern. My wind generator niether has skip rings nor magnets. Patent application is under examination.

  5. Yes, VAWT are less effective than HAWT. But for many uses, i don’t care. I can make a VAWT for cheap, generate some power, even with average precision in the fabrication. A HAWT will need more precision when manufacturing it, need longer poles to mount it, a swivel base, etc…

    If you’re trying to make power in large quantities, sure, go for state of the art HAWT. But for the hobbyist that needs to generate a few tens of watts, the vawt will perfectly do. And, most important, we’ll be able to do it at all. I’m not sure i have the manufacturing capabilities for a HAWT blades set, the swivel base, check for weight repartition, a large enough slip ring for the current i want, and all of this with correct waterproofing….

    I live in a hurricane area, so i also have to be able de remove the turbine quickly, which is much simpler on a lower pole…

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