View Full Version : Wind power (generator)
02-07-2008, 05:49 PM
I am building a wind powered generator this year. It will be a low speed unit due to the high average wind speeds here. Pobably a Savonius or Darrieus type wind turbine. My intention is to use it strictly for resistance heating. Two wires on either side of a big coil imersed in a vat of liquid. It is possible to use old alternators and generators but I was told that certain kinds of electric motors can be used as well. Anybody know what these motors would be from or how to identify them? I searched our archive but could not find what I was looking for.
02-07-2008, 07:05 PM
Cool to use stored hot water, pun intended.
Any Permanent Magnet DC motor will function as a ready DC generator, drawing no energy to wait. Size the machine to be able to handle the energy fed into it.
The only downside coming to mind at moment is that brushes may not be optimum placement.
If you charge a battery with it, you will need an appropriatly sized diode, and always turn it in the same direction.
Automotive alternators are plentiful and CHEAP, and available with surprising ampacity.
Will work well over a huge rpm range.
Depending only on the fan to decide turning direction.
Use a radial fan it will work well either way.
They are built to run under full load in a hot environment.
Unless you rig one for permanent magnet, you may need a battery for energizing the field.
HOWEVER, they can be rigged to switch off at rpm below useable range, and then draw no energy to wait.
You can parallel several with staggered switches to stage the load.
Good Luck Ag
02-07-2008, 09:41 PM
PM DC, obviously.
Regular DC generator or motor also works, but must be flashed to establish a field in order to "build-up".
PM AC motor works fine also (widely used in HVAC).
Finally, a regular AC induction motor will generate if it is "flashed" and has a load on it so it will "build-up". 3 phase induction motors are cheap and work well for that, but a single phase will also work. You don't need the start winding..
02-07-2008, 10:37 PM
You may want to take a look and research on www.otherpower.com.
There is a lot of info there and you may connect with other people doing the same.
The car alternators waste almost 6o Watts just to keep the field energized. I would guess that you would not have more than 200 or 300 watts max when you finish.
The permanent magnet generator (PMG) get you the most power for the buck and the available energy, be it wind, hydro or whatever.
I have a PGM that is made ins Australia or New Zeland, called Fisher & Pykel. It is utilized in the washer machines that are super efficient.
Here is the one I utilize in the creek to generate electricity for the cottage.
02-07-2008, 11:10 PM
I once took an alternator apart and replaced the field coil with some ring magnets like speakers have. It was only good for about 40 watts with that setup, but todays powerful nib magnets would boost that at least 5 times, probably way more. It's not exactly trivial to press the armature apart, but it can be done, and those nib magnets are so powerful now that it would be worth trying. I can see getting 500 watts out of it easily. I wonder if there's anybody out there who's tried that- that gets you away from the brushes and the loss due to supplying field current, but requires that the cogging torque be overcome before it will turn. With a windmill (or watermill, for that matter) this wouldn't be a limitation at all. Power available in wind goes up exponentially as wind speed increases. Re-using an alternator makes the package lighter and probably smaller for the power generated than using an ac motor as a generator (or alternator), but this would be largely because of the speed difference. A car alternator requires high rpms before the rated output can be made, so you'd have to come up with an efficient way to boost the speed from the windmill axle. Make that efficient, low maintainance, and long lived in one package-
Another thing to consider though- you're going for heat, so maybe consider what ways there are to generate heat aside from electrically. One way is to pump a fluid through a restriction, which in this case could be small diameter tubing. An array of this tubing would be the heat exchanger inside the water tank. The pump could be a suitable hydraulic pump, maybe even a power steering pump. Either fluid would be free from freezing or boiling, and is the lube for the pump.
My brain is starting to boil on this idea- it might be a good system to use because it gives a way to match the speed of the pump to the power being generated, via a controllable restriction valve (which would be the heat exchanger). Hmm. This valve could be part of the overspeed control for the windmill blades. Obviously, if you closed the valve, the blades would stop rotating. By controlling the valve you have a way to both control how much heat is being generated and how fast the blades are allowed to rotate. Hmm.
02-07-2008, 11:23 PM
The motor I had in a creek water wheel was a DC excitor field type motor, no permenant magnets. You had to power the fields with a small amount of dc, via a bridge and ac.. then the armature put out enough to go to some heater elements I had. They never glowed red, but made heat..
By the way, the harley altenator is a coil and rotating magnets around it.. YOu test it by plugging in a 120 volt ac bulb.. It will light it up.. They have them cheap on sale at times for less than $65.. A smart man could stack them.
Here's one that ate the splines out, wrecking the harley engine.. Actually it is a high amp model they left a spacer out and that destroyed the engine.
02-08-2008, 09:28 AM
How do you get to post the picture as you did?
I used photobucket and only the link came! (see my posting above)
02-08-2008, 10:27 AM
GS, like everyone stated, DC prem. Mag electric motors are well suited for this purpose, You can find them at surplus stores or even on E-bay, Knowing the specs and what you need takes some doing --- I found mine simply by testing the units by hand and taking a crap shoot at what kind of drag they were going to create and also had the benifit of changing my gearing to dial them into the range I would need,
You can find out if an electric motor is a perm mag simply by turning its shaft and feeling if theres a resistance change with the two wires crossed, if its got Just two wires (usually a black and a red) and there is a resistance change when wires are crossed it means its a dc perm mag,
My motors turned very free and when i crossed them i could barely rotate the shaft, if the wires were not connected good they would actually arc just my hand turning:eek: I knew they were going to be good little power plants even at low RPM's
If you go with the Savonius your going to most likely need a speed increaser --- I don't recommend this as it wastes precious energies that your already trying so desperately to conserve -- but if you have to the reduction gearing in many little japanese starters can be reverse geared to increase the speed --- They then can be coupled to the DC generator, maybe to the point of having the Torque'y Savonius get into its usable rage for the generator to work OK --- You got your work cut out for you, I would much rather try to match a conventional type windmill to a generator as its always better to have a one to one ratio for maximum efficiency and they spin at a good enough clip to achieve good harmony... The Derrieus's get wipping and have good potentual for a 1:1 ratio
Just a point of reference for what some have constructed for wind power.....
02-08-2008, 11:30 AM
Wow those guys are the rel deal! making their own props and such, incredible,
I cant find the name for the one im thinking of, its like its got those twin vert. "water heater venting diverters" (that fit into the center of the gas heaters to milk the waste heat)
Anyways, if I were to build one or buy one I would go with staying close to conventional --- the power is hard enough to come by as is and I would want to keep it as efficient as possible, this is where a lift machine (like a tripple prop. horizontal) is self adapting to many wind speeds and a drag machine (savonius) will trip all over itself, Just my opinion --- but - artistic value -- I think id go for the vert. water heater diverter turbine;)
02-08-2008, 06:22 PM
Boomer and Gonzalez 2 : I have no shortage of wind power here. The problem here is the winds a so high (40+ mph) on a calm day, that it becomes a problem to control a conventional prop. Vertical turbines work best and as far as gearing up, that is my plan. I'm not sure I understand how to identify a perminent magnetic motor such as found in "washers" ? DC motors are scarce to none existant but there a plenty of old washers if I can find the right one (s). Ganging them up makes sense. Another question I have, is it necessary to protect the motor from overheating? This is a cool northern climate and a warm day is 15 C and a hot day would be 16C. Mostly this heat will be used for the winter, but I still wonder just how much resistance these units, or any unit for that mater would take?
02-08-2008, 08:54 PM
Given your high average wind speed, probably your most important consideration is how to not allow the blades to overspeed. If you can incorporate some kind of self-feathering mechanism, then you would have an easier time developing the suitable speed increasing mechanism to drive the generator. Without suitable electronics it would be pretty easy to burn out the generator if it was geared to produce somewhere near rated power at a certain windspeed, then the wind picked up for a time.(assuming you didn't have any kind of mechanical blade speed control)
How much power are you considering harnessing? That's going to make a big difference in what generating device would be suitable. If you're looking at a couple kilowatts or more, then none of the dc permags are going to be suitable, unless you find a rather large one. If you design based on a rating like, say, a treadmill motor, where they're rated at 1.5, or 2.5 horse, they aren't going to last long if they're delivering anywhere near those ratings, though any of them could do it for a short time. A brushless permag generator (or alternator) would be better, but I doubt you'd find a higher powered unit that didn't cost a bundle.
What I've seen in many wind power sites is the builder making his own generator by arranging a number of high strength magnets on the rotating part, and winding his own coils for power takeoff. If a person were to be willing to do this, then a low speed unit becomes more practical, and there's none of the messiness of speed increaser units, alignments, etc. There's a fairly basic relationship going on here, and that is the slower the drive shaft, the larger diameter the array of magnets should be. In a case like this, if the wind picks up to a high speed, the rotor still doesn't go up to ludicrous speeds, so it can be a good thing if there's a way you can see to go direct drive.
I'm no expert on this, but I know there's a lot of ways to do the job, and not many of them are really suitable for one reason or another. I'd have to say that if you stay within several hundreds of watts, you have more options with regards to the generating unit, and you'll find a range of choices in the dc permag hardware. Going up in power might mean that you have to stick with proven hardware, which probably is pricey. I'm interested to hear what your final package will consist of.
02-09-2008, 01:06 AM
I was interested in wind power in 1983.
We visited Ed Kennel's Shop in Seattle and bought some gear.
Three of us electrical engineers did some wind surveying and found that the Seattle area is a lousy place for wind power.
I wound up building a Solar home, and Seattle is a lousy place for solar too:)
I super insulated the house [that worked], and never did anything practical with wind power, despite all the time and money.
Ed, I guess left in ~1984 and went to Altamont to be project engineer for a wind farm.
I still do power conversion consulting, but right now I am working on a luxury persona jet design starter generator system.
I still have file and books on wind power from 25 years ago, but I think I left my big Clark-Y foil prop at the solar house.