Homemade Wind Generator Alternator
I am making a VAWT out of scrap for my senior project. I am going to use it to power a well that uses 240 KWH per year and runs at 230 V. It will be about 15ft in the air. My question lies in converting the mechanical energy to power. Should i use a car alternator, a Dc Generator, or a Permanent Magnet Generator? Also, I am planing on connecting the generator right up to some car batteries and those up to the well; can I do that and if so, how should I wire it and how many 12v car batteries do i need.
Specs: Air scoops will extend out about 5 ft in each direction. Average wind speed is about 7.5 mph.
Also, how should i mount it on a 15ft telephone pole (once i have planted the pole in the ground)
Hi Matt, just looking over your numbers here, I have to ask, why are you planning on using a VAWT for this project? Vertical turbines, even the finest engineered ones, are horribly inefficient. They generally run in the 5 to 8 % range for commercially manufactured ones, and much less for home scrap built models. A good quality horizontal turbine is in the 25 to 35 % range. This is the primary reason all the wind farms being built today use this type. The reason for this is that most of the energy developed by the downwind air scoop is used pushing the upwind scoop back into position, so very little is left over to run a well pump, or anything else.
You pump uses 240 KWH per year, or about .65 (650 watt hours) per day. At that rate, assuming you stored your wind turbines power in a battery, it would have to develope at least 40 watts continuously (24/7) to keep up with the demand. Factor in the calm periods and losses with the inverter and battery charging, and you’ll need at least a 100 watt unit to do the job. Looking at the formula for wind power at the American Wind Energy Associations website, and accounting for the low performance of the VAWT, and you end up with scoops the size of a school bus to reach the swept area that is needed to do this. At least with a horizontal unit, you can get by with 1/7th the swept area, but you’ll still need at least 5 square feet of total swept blade area at the correct RPM range to make your needed 100 watts on a breezy day.
What I’m getting at is that I don’t think you’ve taken a good hard look at the numbers here. Even if you could pull off the turbine, you need battery storage, which is strictly DC, and a large inverter, maybe 2400 watts, which is expensive and can’t be built from scrap.
A Wind Turbine for a senior project is a great idea, but you will have much better luck if you can tone down the load and move it to the DC side of the system. Instead of the well pump, how about LED lighting. You can buy 12 volt strips, or make your own with parts from a supplier like Marlin P Jones to save money. Or use a small inexpensive inverter, like a 400 watt unit from the auto parts store to run Christmas type LED light strings, they only use 2 watts per string. There are lots of possibilities, you just need to add up what you are trying to do a bit more accurately. Using scrap parts to make the VAWT to run the 230 AC pump is like moving 400 tons of gravel with a Ford Pinto. It is possible, but extremely difficult.
We live in a solar and wind powered home right now, our turbine is a commercially available unit from Southwest Windpower, rated at 900 watts, and can barely run our small 1100 square foot home on a real windy night. There are some great sources below where you can learn more about the technology, which is really the point of the senior project, to learn a great deal about something. You still have plenty of time to get into it. If you decide to Build A Turbine, here is what I would suggest. Look into 24 volt electric scooter motors, they are permanent magent, ball bearing movements and run at lower RPM’s than other units. Car alternators are terribly ineffecient with bushings instead of bearings and pulleys instead of gear cogs. At 24 volts, it would be easy for a 100 watt motor to charge a 12 volt battery bank. Solar panels designed for this operate at 18 volts, and they work fine too. I would use a load controller instead of a charge controller, which will let the wind turbine produce whatever it can, but take any excess and drain it off in a small array of incandescent light bulbs to keep the batteries from over charging. Then use your 12 volt battery power for something small but interesting, like a 12 volt fan, CD player and some LED lights. We run classes in the 5th grade doing this all the time, the kids love it. You can make your own turbine blades from wood, or old box fan blades perhaps. Good luck Matt, learn what you can, and take care, Rudydoo
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