VAWT idea

[inode buddha]

Well, I'm still trying to get the basic ideas here, but the VAWT thing fascinates me. Now, the easiest VAWT for me is something like a couple of oil drums cut in half lenghtwise; tho I would use a lighter material like fiberglass if possible. My real question is "What if somebody puts a VAWT like that onto a genny that is almost the same diameter as the swept area?"

In other words, a really large diameter genny. I could see casting the stators in sections to prevent cracking; or else use a really slow cure time like a week or so. Either way, that's a lot of copper and magnets. What would the ratio of genny diameter vs swept area be? (assuming double rotors and neos)

Way I figure it, a large diameter adds up to a large linear speed at any RPM, which increases the voltage to the point of being practical (rectifiers and all).

Anybody got some thoughts on this?

[Phil Timmons]

Yeah, I have pondered just how big you make a practical VAWT.

Like say for instance a cone shaped roof for a whole building that was actually a VAWT -- so the whole roof spins.  And like you observed, the rotation speeds can get MUCH slower for the larger diameter.  

Means you could even have "flaps" that open on the wind-catching side, and close on the return side.  

Started scheming like this because of the property tax issues in Texas.  RE equipment is property tax exempt.  So if the entire roof of a house were an RE device, that entire portion of the house should be tax exempt.  At least I guess it would something for the appraisal board to fight over.

[electrondady1]

 this is the idea that i keep coming back to as well .  as i drive in the country i keep noticeing all the obsolite farm silos. 20' in dia. and 60'-80' high. what a wonderfull platform to produce power . i've got lots of design ideas but no money for testing.

[Phil Timmons]

hmmm, that is not too shabby of thinking.  

I like that.  Was pondering with the Mrs. that we could away with one in the city if did it as the cone on Victorian style house . . .

Anyway, how much money do you figure it takes to put a spinning cone (or dome, or even a large cylinder hanging down the sides) on an old silo?

Be sort of cool to put a spinning "onion" on an Eastern Orhodox church, too, huh?  (yeah, God is gonna zap me, one day )

[electrondady1]

phil, god would bless you, your children and your children's children if you do your bit to rescue our world from the giant oil conglomerates(got to be the devil)

 probably get a thumbs up and a "way to go" from old lord budda as well!

i've got some equity and could maybe get the downstroke , but i could never carry the payments on a farm ,1/4-1/2 million cdn.

better at this stage to design/manufacture a product to sell to others .

got to start some were, like maybe 2' dia.

[Phil Timmons]

ahhh, I see where you are coming from in the $$$ reference.

(btw to idone -- sorry on hi-jacking your diary )

If I may duck away from the sacreligious -- and head directly to the carnal . . .

when it comes to getting use of an old silo, I was thinking less in terms of marrying the girl, and only going for a lease-by-piece sort of thing . . .

to paraphrase the dairy metaphor . . .  why buy the farm when you can use the silo for free?

My "walkaround" experience is that folks like it when you offer to bring them "free" income and "free" energy.  I was thinking more along the lines of share-cropping the the power with the silo's owner.

I have been exploring creating a "backyard grid" around here (an industrial section of Dallas) where I sell power directly (at a very discounted price) to industrial use neighbors.  Looks VERY popular.  I am thinking the same for a silo owner.  Especially if they have any real power use on a functioning farm, itself.

Do not you think farmers would let you set up on their site and you/whoever would probably retain ownership of the hardware -- it is experimental, afterall.  And for the site use, they pay you a discounted power consumption rate.  Seems like it might be a good business use of this stuff?  Only thing better than toys is making money with the toys, huh?

At any rate, that only leaves hardware costs -- which chances are with this crowd is made mostly of surplus/junk -- and those costs can be recovered directly by the "customer" who owns the location.

Looks sweet to me.

[Bruce S]

Phil;

   Are looking at the silos made out of concrete or the newer ones made out of metal?

I've looked longingly at some of the older ones made out of concrete back home in the farm area of MO, but if it's the metal ones I dunno. I've seen those take flight on some of the wilder winds my younger sister's closet neighbor  in Dixson , MO had a metal one end up 2 miles away when the last twister came through, while the older concrete one was missing only the door.

With this in mind,would you be using in the inside of the silo for the mechanics of the setup or would you need another building for the controls metering and such?

I would think that if you allowed the farmer a certain amount of free power, say to run the pumps of something they would be more apt to listen. Most around the homestead get up and leave when you saythey're going to get something "just" for the use....

One more question?

Have you looked into asking the locals for a grant to try this? seems the times are ripe again for grant money to be pushed for Alternatives.

Bruce S

[electrondady1]

i was thinking of the concrete ones. so meny i drive by don't even have a cap on them. got a chance to look at one close up and take some measurements last fall on a job site. it was formed from a type of interlocking concrete block and used  circular steel rods  around the outside to  give it strengh . typical construction i think.

 i never thought  about leaseing one!

 i never thought about  government grant money !

  hey guys , this might be doable.!!

[inode buddha]

Nah, don't worry about hijacking diary

I think the silo idea is neat, I didn't think of that one. I was thinking maybe a 3-section savonius, with the sections displaced from each other by 120 degrees (vertical) but put it on a axial-flux genny that is maybe 3 feet in diameter. Cast the coils in groups of 3, use rectifiers and a star-delta switch, etc.

[Phil Timmons]

Well, actually all I was really trying to do was sort of brainstorm with electrondady (on inode's diary) about cheap, large (pre-existing) windmill sites and how to get their use without incurring the cost layout of purchasing something that does not have much tangible use to him or the project at hand.

I suppose something like billboards could fit that concept, as well.  Probably some other things if we ponder it, too.  I have a friend with a surplus (concrete) 3 story military hospital.  I think the top of the elevator drive house is something like 60 or 80 feet up.  He has asked me about mounting windmills on it.

But towards your point, I would concur that the reinforced concrete silos would vastly preferred over metal ones.  Many metal storage structures require they be filled to even support their wind load rating (e.g. water tanks -- empty, they blow over).  Reinforced concrete, on the other hand is some TOUGH stuff.

I guess if were spec'ing the system, my bias would be not to require additional buildings, as the site method being discussed (at least in the path I wandered) is owned by others.  I would suppose the controls and power distribution would be integral to the framing system that mounted on the existing equipment/sturcture.  That way it installs easy and removes easy.  Just a disconnect and flex/seal-tight conduit to tie into the site power.  All the rest comes and goes.

I like rural Missouri.  Played Army out at Lost-in-the-Woods.  (Ft. Leonard Wood)  The Piney River valleys through there are lovely.  Might be home if it were just my choice.  

Personally I am not real big on grants in this domain.  Does not mean I think they are bad things, just the guys I watch on that path seem flustrated and less productive.  My bias is to think cheap and not need the beggin' money.  But that is just my bias.  But if someone wants to do a grant request, I will help -- I write bid/proposals all the time for our real cash money projects.

[inode buddha]

My neck of the woods NY/New England area, all the silos are stone or block of some kind. Prolly half of them are abandoned. Only problem is that the gov't is real pain about putting anything in the air. It's easier to fly something if you own the land or a ranch or a farm, but they still make it a pain. (paper work)

[ghurd]

Not sure about other places, But concrete is the 'new' type here.

For maybe 20 years now.

[ghurd]

Don't ask.

Don't tell.

unless insurance could be a factor,

'much later', I hope.

[kitno455]

inode, size of stator is an interesting question. if you have a slow shaft rpms, but you want high Hz (say to use a transformer) then you want the larger diameter, with more coils, or you have to have overdrive gearing. the problem with large diameter is how hard it becomes to support the thing, and keep the airgap tight. you wont be able to use most types of bearings at the outer rim, cause the linear speed is so high. so now you are looking at more expensive contruction.

would be interesting to see how that compares to any losses incurred by the geartrain alternative. maybe there is a happy middle ground, at 20 to 24 inches?

allan

[MountainMan]

What about putting a small genny on top of each and every already ugly power transmission tower in the country.  Probably wouldn't need the generating stations anymore!

Equip each one with maybe a 1000 watt generator and some electronics to upconvert and synchronize the juice to match the power in the lines.

There are probably a million ugly assed towers in the country.  A HAWT on each one would probably make them more aesthetic and generate a billion watts of energy!

Actually I would be more in favor of taking all those towers down and just have every house in the country generate its own energy.  Those towers have to be the ugliest thing we humans have done to this planet.

jp

[inode buddha]

Good questions IMHO. I don't think that the air-gap is that much a problem if you start with something fairly stiff like 3/8 plate rings and angle iron for spokes. You could lap the difference with valve-grinding grit and toothpaste (which also works on CD-ROM's by the way) and close the difference right up to a very close fit. The day I can't hit 1/16 over a 100-foot length is the day I'm gonna retire due to being useless. A little piano wire and a big level goes a long ways.

I don't really care about gears, if I can help it. It's do-able, but its still a loss. Yeah, expensive construction, but I had assumed using tapered roller pillow block brgs. Or at least ball bearing blocks. The freq. isn't really a concern if you're gonna rectify it anyway; electronics could handle the rest such as freq. matching.

That was my idea anyhow.

[electrondady1]

i have done a lot of sketches for large dia. mills and it seems to me that for a vawt, there is a point were a radial flux design becomes more practical for construction.

 ive been experimenting for over a year now with ceramic mags.(free). the only way to get respectable power is to use a lot of them , and give them a good spin. some of these mags have been in 5 different genni lay outs. i want to give them all a permanent home before i move on to neo mags. i think a radial flux 20+"dia.

having said all that windstuff ed is pulling some very respectable power on an 8" dia. rotor.

as far as my silo idea goes, the forces involved as a wind mill base are different than those they were designed for. that would need to be taken into consideration.

 some times farmland can be subdivided , the old house, barn and silo could be seperated from productive acerage.

when you start geting that large a devise , i think permanent magnets might not be practical any more. at that point, runing a bunch of auto alternators on the cercumferance would work .or maybe a very large generator tied to the central axis.

 

[electrondady1]

mt.man,

 your vision is practical and logical and very green . but others with different agendas are in contol.

 what are you trying to do? cause trouble?

[maker of toys]

try this one on for size:

build, say, 3  (or more) more-or less normal-size axial flux alternators, on, say, car hubs.  extend the steel backing plates of the rotors a bit more than usual.  Put a high-quality (4130?) 'tire' on the outside of said backing plate.  place the altenators below the perimeter of the VAWT at an angle (much like the rollers in a tapered bearing), with PLENTY of rigid support (concrete pillars?).  place the VAWT rotor on the alternator cum bearing units, drop a tension member (cable? long, thin rod?)  through the center to tie the whole thing to the ground, using another bearing (self-aligning?) to allow rotation of the tension member, and voila!. . . rigidity, scalability, alignability, durability, repairability, standardization, decent alternator speed and easy construction of alternators.  you could make the bearing 'race' for the bottom of the turbine out of bent tubing, or some such, and grind it to concentricity using the  tension-member bearing before putting the vanes on it.

or maybe use the 'car hub' idea a bit more and springload the load- bearing alternators

just a thought.

-Dan

[kitno455]

completely crazy, i like it

unfortunately, using a big hanging weight instead of an upper bearing is sort of a waste. what about strapping 4 telephone poles to the outside of the silo, have them extend above the top, and build an upper platform, with bearings in the center. the poles wont block that much wind.

i would not use the gennies to support the prop, the amount of weight would flex the magnet rotors, the airgap would go screwy, and the mags would pop off. also- touching the outer edge of a 24 inch disk to the outer edge of a 15 foot prop gives you ~7.5:1 overdrive. using a 10 inch tire on the genny shaft instead gives you ~18:1, with much better grip under load. steel to steel will slide under load.

go look at how the local fair portable ferris wheel works, you can get neat construction ideas there.

allan

[inode buddha]

Actually, you can make huge rotors with permanent magnets. The local hydro plant did that, IIRC they use a 26 foot diameter and of course it puts a zillion megawatts or some huge figure like that. The downside is that it's expensive and took a decade of planning.

[maker of toys]

mmmmMMMmMM. . .  I dunno if a set of 11" chevy (toyota, bmw, rover, mercedes, URAL, pick a truck, any truck) brake disks are going to flex much even holding up 300 or so pounds apiece.  and if they do?  bolt 2 face-to-face, and use one to support the load and the other for the gen rotor.  

on the center tension member, I was not particularly advocating a weight (though that would serve much the same purpose); more of a centrally located guy wire arrangement to 'preload' the 'bearings' and resist the wind pressures' overturning moment.  there's nothing wrong with a 'top-deck' alignment bearing; it might be a easier design solution.  I just figured on trying to keep everything on the 'ground' for ease of maint and repair.

 a rubber tire, while certainly better from the COF and transmitted vibration perspectives, gives up a lot of efficiency to flexure. a SOLID tire might be better, but I still think it would be a poor choice for a supporting member just because it WOULD wear . . .leading to alignment headaches for the turbine. that can be designed around with adjustments and springs, etc, but KISS is a good mantra for power-generaton equipment.  so I stuck with steel.

 if you're doing rubber, why not go back to a generator that's separate from the support structure and use a serpentine belt for your drive/speed multiplication?  that might turn out as the best option; i'm just thinking out loud here.

  my design criteria here is to allow a backyard experimentor to fly a bigger VAWT without having to resort to all sorts of special tooling and custom parts. . . leverage the stuff that people here can already make with pretty simple tools.  Sure, a lathe and a mill might come in handy, but using the car-hub type alternator on a SUV brake disk with a steel 'tire' shrunk on it via the kitchen oven (steel tire provided by E-machineshop or the local fab shop/ metal supplier. . .) allows people to run something bigger than a 55gallon drum conversion without too big a capital outlay.

the railroads don't have too much trouble with steel-on-steel slippage, and thier torque requirements are pretty high. <G> so I ran some numbers. . .

1:15 multiplication accrues to a 12" od brake disk-with-wear-ring on the tip of a theoretical 15' od turbine.

 If you figure on a dry steel-on-steel contact having a 0.15 COF, (discounted from book value of 0.25) and the turbine rotor wieghs, say, 300 lbs; with 3 of 12" OD alts, that gives you basically 7.5 ftlbs limiting torque to drive each alternator. my calculator says that's enough for about 300 input watts per alternator at 300 alternator rpm. ok,  so that's a little low for a 11" PMA, but not completly pathetic, either. . . and with that much alternator rpm available, cut-in speed isn't such a concern, and you can use nice, thick windings for low losses in the alt.

if you use the 'central guy wire' to preload the 'bearings', you could get 2 or 3 times that without stressing the structure overmuch. . . assuming that sufficient torque was available in the turbine to make the extra effort worthwhile.

(at 300 alternator rpm, you'd have 20 turbine rpm, or a bit over 5 mph tip speed; the alts would be extracting the equivilent of ~330 ft lb. in the un-preloaded state.  I'll leave it to the turbine gurus to figure what sort of wind you'd need to get a 15' dia Savonius or Lenz turning at 20 rpm, and how tall you'd need it to be to get 1kw out of it.)

-Dan

[ghurd]

Green?

What about the zillions of dead birds?

I feed them all winter, but not in the summer.

What about the noise?

I can't hear my 1800W 5 speaker surround sound movie.

Even worse, the view from my electric heated house?

I can't see all the cell phone towers any more...

Let alone the plume from the coal fired electric plant.

I can't even get a 100% clear view of the 1,000's of acres of shingles from the new housing developments.

OK.  I'm done.

[electrondady1]

it would be nice to use existing tech. to build this thing . i was thinking the front spindle, bearings, hub of a big truck. from that point a lot of spokes made of steel or even  presure treated 2x10's or both. conecting all the spokes  at the end, a rim which would work as a driving wheel. i think id place all the genies beneath the rim to stablise the thing, the genies could be mounted on a circular concrete foundation.

 so at this point i've got a nice round deck that  just happens to rotate when the wind blows.

 now build the same thing at the top of a silo.

 if times get tough it's a wind powered fortress, if times are good it's a rotating nightclub.    

[Phil Timmons]

Have played with some of those biggie-sized dam rotors.  

Actually the project we are heading up to in Illinois is a dam site (but not working on the rotors on that one).

Anyway, if I have been following this conversation correctly, a potential "at risk" or difficult portion of homebrew large diameter rotors is maintaining the gap correctly at the edge?

And that is a problem because with the long distance between the centeral bearing hub and the rim where the coil gaps are critical means that even a slight deflection would cause the gap to open too wide, or maybe even grind together?  Is that correct?

A possible solution to that could be a much lesser central hub bearing, and instead let the load be handled by bearings at the rim?

For example, create the outer rim of "rolled" angle?  Are you all familiar with that?  You put normal, straight angle iron into a roller and create a "hoop" of it?  Or sections of a hoop/circle -- I guess properly called a secant?  Anyway, such a hoop or circle can hold a very high load with little or no deflection.  I am thinking that Cam Follower type bearings (sort of like steel roller skate wheels) could run around that rolled angle, holding the gap distance exact and correct.  A design like that should be able to handle thousands of pounds (actually tons) of sideload with little or no deflection.    

One could use the hoop to mount the coils, as well, and the rotor gap distance would stay exactly correct as it passed over.

[electrondady1]

ive never seen the material you describe phil, i'll ask the machine shop if its available.

[Phil Timmons]

We get it done for architectual sized steel -- like maybe 3" X 5" angle, 1/2" to 3/4" thick.  We use it to match existing curves on equipment or buildings if we are doing some modifications.  Not all machine shops have the equipment to do it.  I would guess maybe most do not.  Dunno.  Around Dallas and Fort Worth there are a couple of the really BIG shops that do it -- big as in Zepplin-hangar sized shops.

Their roller machines are big and ugly, but something like the ones on this page >>>

http://www.wikco.com/rbndr.html

But I would think we would not need real heavy angle for what we are talking about  -- maybe 2 X 3 X 1/4" thick?  Dunno.  I usually get some good advice from the mechanical guys at this point.  I am just an electrician and electrical engineer.

Best to deal with folks that really know their stuff.

[electrondady1]

 thats a very interesting machine and the price seems reasonable. i wonder if the surfaces would need to be machined after the bending process.

 it shure would make my next geni easy.  

i studied industrial design , and if a guy could get the design finalized,  that would make  production very inexpensive.

[inode buddha]

Yep, I know about rolled angle -- I've made some of it in the past. Best bet is to find a fabrication shop or a large steel processing outfit such as Ryerson.