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Re: Vertical versus horizontal axis wind turbine - this says it all for me

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  • thorthesailor
    My 500 watts of solar has produced more than 107kWh in less than 8 months of connected time. Cost - about 4.25/watt. Just for some perspective. Michael
    Message 1 of 51 , Sep 3, 2011
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      My 500 watts of solar has produced more than 107kWh in less than 8 months of connected time. Cost - about 4.25/watt.

      Just for some perspective.

      Michael

      --- In axialflux@yahoogroups.com, "Charlie" <charlieknox@...> wrote:
      >
      > IMHO, this says it all:
      >
      > http://www.mge.com/environment/innovative/urban.htm
      >
      > If an electric utility can't make a VAWT work, it's probably not a winner. It all sounds good until you click on the "Live data reporting", then "Lifetime" - 107 kWh in 2 and a half years - less than $15 worth of electricity on a $40k investment.
      >
      > Charlie
      >
      > --- In axialflux@yahoogroups.com, Thomas Loeber <tomloeber@> wrote:
      > >
      > > VAWTs have advantages and disadvantages. HAWTs have advantages and
      > > disadvantages. I suspect if some basic research were put into VAWTs they
      > > may make for the cheapest, home built and maintained highly efficient light
      > > weight wind mills.
      > >
      > > Advantages of VAWTs:
      > >
      > > Immediately able to use power from wind from any direction.
      > >
      > > Potential disadvantages:
      > >
      > > Current designs are big and lend themselves to ground installations without
      > > as much height as tower or otherwise hoisted assemblies. Large size also
      > > necessitates linkages between momentum given components and electricity
      > > producing medium, taking away from efficiency, incorporating complexity.
      > > More mass also means more energy is put into building momentum than into
      > > spinning.
      > >
      > > So, aim for light weight highly efficient VAWTs with no slip rings or
      > > brushes with counter spinning rotors about the fixed electricity producing
      > > medium.
      > >
      > > Coils would work, of course, but I think some basic research should be done
      > > into derivations of the homopolar motor, the invention of Faraday, I think.
      > > Appears there has not been experimentation with counter spinning magnet
      > > assemblies around a fixed disk of copper.
      > >
      > > I've got an about 1/8" thick sheet of copper, enough to sandwich a disk
      > > between two spindles of the Quantum Bigfoot hard drive. Those spindles
      > > directly bolt together to make two counterspinning 5.25" diameter discs with
      > > sealed but maintainable steel ball bearings.
      > >
      > > I'm going to use Hotine Vane assemblies which I plan on affixing directly to
      > > the magnet rotor disks (from the old hard drives), two vane assemblies at
      > > 90 degrees to each other per each rotor. I'm thinking the whole assembly
      > > with bird protecting cage will weigh about 30 pounds. The idea is to make
      > > them cheaply and use an array of the devices, maybe suspended on cables
      > > between trees, hung from building overhangs, along the sides of skyscrapers.
      > >
      > >
      > > I think that if these things are simply hung from things the bringing of the
      > > units out of alignment with vertical due to higher strength winds will
      > > provide a governing mechanism to give them more endurance. I want to set up
      > > some research rigs. The size of the sails and their material will give some
      > > flexibility in as to how much the unit will go out of alignment with the
      > > wind and should probably allow designing for best use of that as a governing
      > > system. Of course, their light weight and ease of lowering or raising,
      > > removing and installing, can prove a means to help protect from too fast of
      > > winds.
      > >
      > > The HAWTs have little feathering of their working surface. A large
      > > percentage of the returning "blade" fighting the wind decreases potential.
      > > Of course that is true for existing VAWTs too. The Hotine vane assembly
      > > allows avoiding that.
      > >
      > > The HAWTs lose power by having to use some to turn into the wind.
      > > Counterpinning rotor generators could not work at full efficiency due to
      > > one blade needing to be smaller to facilitate the assembly turning into the
      > > wind, at least for one such realized attempt. VAWTs to date are too bulky
      > > and lose efficiency through the need to use energy to develop momentum.
      > > They do not feather all that much either, change configuration on the
      > > returning wind surface to avoid fighting the wind.
      > >
      > > Might another technology humanity has dappled with throw light on this?
      > > Wind power was used a lot in the nineteenth century. Before steam engines,
      > > clipper ships got faster and easier to maintain via the use of many small
      > > sails rather than a few large ones. A whole bunch of small, unobtrusive
      > > inexpensive durable VAWTs could supplant the idea of these specialist made
      > > huge propellers
      > >
      > > For elites to keep people dependent to make money, HAWTs make more sense.
      > > For the efficient production of energy for lots of people, me thinks the
      > > VAWT holds more promise. I've seen some pretty crazy allusion to science,
      > > physics and math and stuff before. I understand a fair amount of math but a
      > > supposed expert never supplied the experimental evidence suggesting the
      > > "lift" developed by propellers is why they will never be supplanted by
      > > VAWTs. Look, there are vested interests in us not getting energy for
      > > ourselves.
      > >
      > > When I put up this youtube video of one Hotine vane assembly built with
      > > Tinkertoys(R) I mistakenly called it a Hotine Rotor. It is actually just a
      > > single Hotine vane assembly. The ones I plan on attaching to the hard drive
      > > discs will have more vane area and actually tight strung sails instead of
      > > fins. They appear to lend themselves to full use of the advantage of
      > > counter spinning rotors without the problems both HAWTs and current VAWTs
      > > require. http://www.youtube.com/watch?v=rcpFqRsGU10
      > >
      > > Tom
      > >
      > > On Mon, Aug 8, 2011 at 4:10 PM, Dan Fink <danbob88@> wrote:
      > >
      > > > **
      > > >
      > > >
      > > > With all due respect, James, I disagree with both of your statements.
      > > >
      > > > --
      > > > Dan Fink,
      > > > Executive Director
      > > > Buckville Energy Consulting
      > > > Buckville Publications LLC
      > > > NABCEP / IREC accredited Continuing Education Providers
      > > > 970.672.4342 (voicemail)
      > > > 970.373.1311 (FAX)
      > > >
      > > > Posted by: "James Morris" james-morris@
      > > > james-morris@
      > > > Sun Aug 7, 2011 7:12 am (PDT)
      > > >
      > > >
      > > > I think the horizontal axis turbines tend to be more efficient simply
      > > > because there has been so much more research in this area.
      > > >
      > > > But, particularly for the home builder, vertical axis in much easier
      > > > to build. The generator or alternator (as you might choose) can be
      > > > built into the base and no brushes are required. But some kind of a
      > > > system is required to protect from winds that are too strong. Either
      > > > the entire turbine must be designed to withstand a 200 mph wind (my
      > > > preference) of some kind of a braking system (I prefer electrical) is
      > > > required.
      > > >
      > > > But there has been some research into highly efficient VAWT devices.
      > > > The University of California funded such a study. Google it.
      > > >
      > > > __
      > > >
      > >
      >
    • thorthesailor
      So - if you are relying on drag your maximum coefficient of power would be .24 compared to .59 for a lift turbine. (From the Betz link) Notice how the Voith
      Message 51 of 51 , Sep 8, 2011
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        So - if you are relying on drag your maximum coefficient of power would be .24 compared to .59 for a lift turbine. (From the Betz link)

        Notice how the Voith Schneider rotates the vanes around the long axis of the vanes - this is important.

        Rotating the vane with the center of rotation at the end of the vane means you are working against SIGNIFICANTLY large rotational inertia than with Voith Schneider.

        Take a look at this:
        http://en.wikipedia.org/wiki/List_of_moments_of_inertia

        Now, picture the Hotine vane as the rod rotated about its end: I=(mL^2)/3

        Now picture the Voith Schneider vane as the rod rotated about its center: I=(mL^2)/12

        Now lets add some numbers call the mass 1 Kg, call the aspect ratio of the vane 10 to 1, so the vane is 1 meter long and .1 meters wide.

        Now, as the voith feathers its vane, it's control mechanism faces an inertia of I=(1*(.1/2)^2)/12=0.0002083

        note that the width of the Voith vane is used as the length of the rod rotated about its axis.

        Hmmm, pretty small. The Hotine version from the video will face I=(1*(1)^2)/3=.3333 inertia.

        So the Voith unit experiences 159 times less inertia for an identical blade. If on every revolution you have to change the momentum of a blade which has 159 times as much inertia, you are almost certain to be significantly less efficient than the Voith Schneider.

        Michael

        --- In axialflux@yahoogroups.com, Thomas Loeber <tomloeber@...> wrote:
        >
        > Thank you Michael.
        >
        > So much advertising below the text. i delete it from this response.
        >
        > Ah, this is more informative, less "expertise" mumbo jumbo. That Voith
        > Schneider propeller is very similar to the vane concept I was first planning
        > to use until Bill Hotine suggested his idea. I had studied wind vanes
        > before I met Bill and was thinking that since wind is a distributed energy
        > source, a number of small light weight wind mills rather than one big one
        > would make more sense as the clipper ships of the 19th century. They
        > evolved over the years to use many small sails rather than few large sails
        > and this accorded easier maintenance and much less down time. The design I
        > was originally looking at had the sails flapping around independently which
        > is easy to see as incorporating some oscillations and vibrations in the
        > whole assembly that would probably involve heavier, stronger materials other
        > than just sails and unbalanced shaking of the whole unit. I understood the
        > original idea was from some inventor in the 16th century. The "Energy
        > Scrapbook" I got that from attributed it to some guy named Vesuvius which is
        > suspect and I have not been able to find any reference to it any where else.
        > I think maybe the book was mistaken. It is different from the Hotine vanes
        > as they are connected from one side to the other so the orientation of one
        > is tied directly to the feathering of the other. I made one Tinkertoys unit
        > with two vane assemblies in '76 and hung it from a low lying branch and with
        > very little wind that appeared to be changing direction constantly, the
        > Hotine unit spun quickly and smoothly with no weird vibrations.
        >
        > The Hotine vanes are not shaped like wings which would be thicker and no
        > matter what their orientation, would present more resistance returning
        > through the air than just a flat sail turned on its side, presenting just
        > the width of its supporting frame into the wind, maybe a half inch or so. I
        > see the savonius and darrieus are essentially turbines but I wonder as to
        > whether or not that term applies to the Hotine concept as I don't know of
        > any turbines that can feather the returning surface at maybe better than
        > 90%. Just roughly, if the individual vanes on their horizontal axes are
        > each two feet by six inches, that is 144 square inches and when feathered we
        > have the width of the horizontal axle only presented into the wind, maybe 12
        > square inches, that appears to be better than 90% feathering. The exact
        > dimension of the vanes has yet to be determined. I am going to experiment
        > and seek to use the hanging of these to incorporate regulation, that is, as
        > the wind exceeds safe operating conditions, the whole vane and generator
        > assembly will tilt off of the vertical so that it is no longer directly
        > oriented. This wont protect against all possible wind speeds but if
        > designed correctly, should offer wider tolerances. For the really
        > seriously dangerous winds, taking the whole assembly down would be easy with
        > these little light weight units I hope to realize before too long.
        >
        > No reason to be sorry for an attempt at bad news. I hope I am not so strong
        > headed as to tie this thing to my ego, what little I have anyways. If you
        > can correct me on some mistaken assumptions, I honestly think I would
        > welcome that. So far though I think you are talking apples to oranges.
        >
        > Propellers have to be made of stronger materials than just sails as they
        > have to keep their shape. This means more of the energy goes into spinning
        > the larger mass and there is always some air resistance opposing that being
        > used to produce spin. For propellers, there is commonly no feathering
        > happening though some plans I understand incorporate a bit of shape changing
        > as feathering.
        >
        > I am just speculating of course. Been speculating on this for some
        > thirty-five years. I have other pans in the fire and thought Bill was going
        > to develop something with his idea. Though he gave me written permission to
        > experiment I never have. If he did patent it that has expired. The other
        > inventor who came up with the same idea who resides near Quebec has offered
        > the idea free to any one to experiment with. Last I knew, Bill's approach
        > was to make one big unit and attempt to use an old car alternator. I think
        > using the counter-rotating concept and integrating the generator into the
        > windmill will mean more effective power reaping potential and less bearing
        > surfaces. Propellers or turbines as in the savonius or the darrieus don't
        > just have bearings of the generator but also bearings that support the
        > shaft. With how I've come to see using the Hotine vanes, there will be no
        > spinning shaft, unlike that Youtube model I made. The feathering and
        > orientation work with the wind, not against it and over the
        > entire surface of the sails, not just at the tips. Some energy will be used
        > for this but very little. It is a relatively small movement of quite light
        > weight materials.
        >
        > Though sails have been used to produce thrust a lot (I know there is a
        > tendency to want to paint some one who appears to be opposed to some pet
        > idea as insanely naive, but, give me a break), I still don't see how the
        > Hotine concept can do that. I've seen "wings" used as sails before but I
        > can't see the Hotine concept as according such at all. Spinning it at
        > faster than the sails can orient or feather might lead to its acting a bit
        > like a propeller but I think that speed will be beyond what the speed of the
        > wind can accord and any thrust it makes will be at 90 degrees opposed to its
        > plain of operation. I'm thinking 300 RPM or less. The orienting and
        > feathering processing happens almost immediately, each aiding the other.
        >
        > With propellers, the lift turns an axle. With my idea, the wind will
        > directly push the spinning of the PM rotors, what little lift is involved
        > serves to orient and feather the vanes, and no need to waste energy spinning
        > an axle. The lift of the propellers has to lift the blades themselves
        > besides spin the axle and the blade is constantly returning into the wind
        > with little or no feathering. Seems to me thinking that propulsion
        > characteristics pertain to reaping power characteristics is at least 180
        > degrees different at least as far as the power force vectors are concerned,
        > really quite dissimilar.
        >
        > Thank you for making it easier to discern what you are attempting to convey.
        >
        > Thomas
        >
        > On Wed, Sep 7, 2011 at 11:05 PM, thorthesailor <sailorthor@...>wrote:
        >
        > > **
        > >
        > >
        > > Yes - sorry, I meant "Tom", not "Thom" - I glanced at the name to the right
        > > of the text box, and didn't catch your signature before clicking "send".
        > >
        > > The differences in design between the propulsion unit and the wind turbine
        > > will be mostly driven by the difference in density of those media, and
        > > partly by turbulence considerations.
        > >
        > > VS units were originally intended to extract energy from water - they are
        > > water turbines. Reference the note above about density.
        > >
        > > The thrust in the case of the propulsion unit is equivalent to the lift in
        > > the case of the wind turbine blades, lift leading to rotational motion,
        > > where in the propulsion unit rotational motion leads to lift (thrust).
        > > Relying on drag is a bad idea.
        > >
        > > Compare
        > >
        > > http://www.youtube.com/watch?v=rcpFqRsGU10
        > > to the animation on
        > > http://www.observethebanana.com/2008/06/05/voith-schneider-propellers/
        > >
        > > Voith Schneider has been working on that style for more than 80 years. And
        > > it still is less efficient than a plain old propeller.
        > >
        > > Sorry for the bad news.
        > >
        > > It gets worse for Hotine, too, IMHO. By changing the vertical orientation
        > > of the blade to horizontal for feathering each cycle, the blade tip will be
        > > swinging against the wind at a greater radius, increasing the loss MORE than
        > > in a standard Voith setup.
        > >
        > > And vertical wings used as wind catchers are well known to function just
        > > fine as thrusters - witness sailboats, and the sailing catamaran which used
        > > decommissioned airplane wings on crane bearings as sails.
        > >
        > > I would study those PDF's and the above link very carefully, if I were you.
        > >
        > >
        > > Michael
        > >
        > > --- In axialflux@yahoogroups.com, Thomas Loeber <tomloeber@> wrote:
        > > >
        > > > Hi Michael
        > > >
        > > > Not sure you addressed this to me. I usually go by Thomas or Tom. On
        > > here,
        > > > maybe Thomas is best and I'll try to sign my posts that way as there
        > > appears
        > > > to be a Tom involved already.
        > > >
        > > > I am afraid I don't see the relative value of these pdfs. I disagree with
        > > > the second statement here: "A propeller/VS drive is an interface between
        > > an
        > > > energy maker and a fluid motion, a wind turbine is an interface between a
        > > > fluid motion and an energy acceptor. They will have minor design
        > > > differences." I should clarify that I don't really know what you are
        > > > talking about in general but I figure you are saying the analysis of
        > > > propulsion devices for ships shows that propellers are the ultimate
        > > design
        > > > for reaping wind energy. I have thought of using Hotine vanes as a means
        > > to
        > > > tap the hydrological cycle, flowing water, tidal currents, rivers and
        > > > streams. The orientation in which it takes the wind and produces rotary
        > > > motion is 90 degrees opposed to the propulsion it might generate if spun
        > > > like a boat propeller me thinks. It would not be good at all as a
        > > > propulsion device. Maybe somewhere it would find use for some kind of
        > > > propulsion but I fail to see that as happening. Seems to me a general
        > > > argument against propellers is that they excel at providing thrust. Some
        > > of
        > > > the power that is being transferred via propellers in wind machines is
        > > > turned into rotary motion of its shaft but some just pushes against its
        > > > mount like propellers do for ships. Every time the wind slows the
        > > propeller
        > > > will be generating thrust, taking away from its intent to spin the axle
        > > > perhaps? I know intuition fails miserably some times but seems to me what
        > > > is good for pushing ships around is liable to not be the ultimate best
        > > > design for reaping the wind. .
        > > >
        > > > Thomas
        > > >
        > > > On Tue, Sep 6, 2011 at 10:17 PM, thorthesailor <sailorthor@>wrote:
        > >
        > > >
        > > > > **
        > > > >
        > > > >
        > > > > Thom - here's an example in the 10,000hp range:
        > > > >
        > > > > Tractor Tug boats use cycloidal drives called Voith-Shneider drives.
        > > They
        > > > > have a really cool mechanism for guaranteeing that a rotating ring of
        > > blades
        > > > > (like wings) is oriented perfectly at all times to create a directed
        > > thrust
        > > > > in any given direction. This looks just like your proposed setup, but
        > > used
        > > > > as a propulsion device.
        > > > >
        > > > > Other tractor tugs use azimuth drives, which is just a propeller on a
        > > unit
        > > > > which rotates around allowing the propeller to push in any direction.
        > > > >
        > > > > Slip is commonly used in boating - it is how far I went through the
        > > water
        > > > > compared to how far I thought I should have gone based upon engine
        > > > > revolutions and pitch of the blade. It is a measure of the efficiency
        > > of the
        > > > > blade: eff=1-slip
        > > > >
        > > > > Typical slip/eff on an azimuth drive with Kort Nozzles:
        > > > > http://www.dynamic-positioning.com/dp2004/thrusters_dang_pp.pdf
        > > > >
        > > > > comparison is made between the two here in a nicely researched paper:
        > > > > http://www.dtic.mil/dtic/tr/fulltext/u2/a328036.pdf
        > > > >
        > > > > where on page 23-24 we see "It is indisputable that for a given applied
        > > > > horsepower, a Z-Drive unit will provide a greater amount of static
        > > thrust
        > > > > than a Voith-Schneider drive" and goes on to provide comparisons. VS
        > > can
        > > > > achieve 85-96% of a plain old propeller, while Azimuths can achieve
        > > 116% to
        > > > > 125% of a plain old propeller.
        > > > >
        > > > > They've already done the design work you propose. The advantage of the
        > > VS
        > > > > tugs is maneuverability, but they are very poor for transits, due to
        > > lack of
        > > > > efficiency.
        > > > >
        > > > > This is 50+ year old technology with big money behind it trying to
        > > achieve
        > > > > best efficiency using some of the best CFD modeling in the world.
        > > > >
        > > > > A propeller/VS drive is an interface between an energy maker and a
        > > fluid
        > > > > motion, a wind turbine is an interface between a fluid motion and an
        > > energy
        > > > > acceptor. They will have minor design differences.
        > > > >
        > > > > Best of luck,
        > > > > Michael
        > > > >
        > > > >
        > > > > --- In axialflux@yahoogroups.com, Thomas Loeber <tomloeber@> wrote:
        > > > > >
        > > > > > That was a critical word Jerry misspelled but that was not my chief
        > > > > > criticism of his extreme negating and blanket condemnation with
        > > really
        > > > > quite
        > > > > > far-out conjecture as to what the future will bring. Seemed a
        > > > > > mean-spiritedness beyond any call of duty was being expressed. Email
        > > > > > discussions as well as forum discussions basically cater to being a
        > > free
        > > > > for
        > > > > > all. Pernicious "kill the messenger" behavior abounds with more
        > > > > dependence
        > > > > > on proclamation than observation.
        > > > > >
        > > > > > Concerning axial flux generators: would that pertain to a generator
        > > that
        > > > > was
        > > > > > not spun by a center axle? I suspect so as I think axial refers to
        > > the
        > > > > > direction of electron flow. Somebody please correct and/or inform me
        > > > > > please..
        > > > > >
        > > > > > Here is what I think the Hotine vanes will give unlike any VAWTs or
        > > HAWTs
        > > > > > out there.
        > > > > >
        > > > > > 1. Almost immediate orientation of the sails to wind coming from any
        > > > > > direction.
        > > > > >
        > > > > > 2. Almost complete feathering of the returning vane.
        > > > > >
        > > > > > 3. Light weight and small enough to be attached directly to the rotor
        > > > > disks:
        > > > > > the generator becomes an integral part of the wind mill.
        > > > > >
        > > > > > 4. Ability to take full advantage of a counter-rotating generator.
        > > > > >
        > > > > > Oh, that reminds me of another question that maybe somebody could
        > > inform
        > > > > me
        > > > > > about. I hear that if you double the speed of your wind, power output
        > > > > > increases more than double?
        > > > > >
        > > > > > Cheers.
        > > > > >
        > > > > > Tom
        > > > > >
        > > > > > On Tue, Sep 6, 2011 at 12:57 PM, thorthesailor <sailorthor@>wrote:
        > > > >
        > > > > >
        > > > > > > **
        > > > > > >
        > > > > > >
        > > > > > > To do a fair comparison you only need to compare two sets of
        > > "energy
        > > > > > > available in wind at the specific site versus energy collected".
        > > > > > >
        > > > > > > All this nonsense about swept areas and heights means you don't
        > > > > understand
        > > > > > > to evaluate a wind turbine's energy efficiency. Try plotting it's
        > > power
        > > > > > > output (watts) versus it's power input (windspeed) (which is a
        > > proxy
        > > > > for
        > > > > > > input power)
        > > > > > >
        > > > > > > True, those items (more height and more wind) would provide more
        > > energy
        > > > > for
        > > > > > > it to collect, but note how poorly it collects energy - which is
        > > the
        > > > > whole
        > > > > > > point.
        > > > > > >
        > > > > > > Michael
        > > > > > >
        > > > > > > --- In axialflux@yahoogroups.com, "prolinuxfan" <prolinuxfan@>
        > > wrote:
        > > > > > > >
        > > > > > > > Although a fair apples-to-apples comparison would have to compare
        > > > > them at
        > > > > > > the same environment, and at the same swept area, which seldom
        > > happens,
        > > > > if
        > > > > > > ever.
        > > > > > > >
        > > > > > > > If one were to place a HAWT at the same poor site locations that
        > > many
        > > > > > > HAWTs are place in, they would probably be disapointed in their
        > > outputs
        > > > > too?
        > > > > > > >
        > > > > > > > --- In axialflux@yahoogroups.com, Nick Andrews <nickjandrews@>
        > > > > wrote:
        > > > > > > > >
        > > > > > > > > Except that the terms vawt and efficiency do not belong
        > > together.
        > > > > > > > >
        > > > > > > > > Nick A
        > >
        >
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