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Forum Index : Windmills : Vawts for Hobart?
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| Rubes Newbie  Joined: 01/05/2009 Location: Posts: 36 |
I wonder how much opposition there is going to be to this proposed installation Vawts in Hobart |
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| 9c12m Newbie Joined: 04/09/2007 Location: AustraliaPosts: 28 |
Probably a lot now. http://www.abc.net.au/news/stories/2010/08/12/2981164.htm |
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| Rubes Newbie Joined: 01/05/2009 Location: Posts: 36 |
Lol, they will probably end up being garden a ornament like mine. 
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Big Al Newbie Joined: 06/10/2010 Location: United KingdomPosts: 38 |
This looks a pretty professional job if a bit flimsy. I'm a heretic and hoping to build a vawt despite a lot of Hawter missionary work. Do you know what was wrong with it? Might help me. Rgds (Beautiful view )ps not even sure its flimsy those cables lokk pretty good. Big Al Every Day is a school day (even at 67) |
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| Big Al Newbie Joined: 06/10/2010 Location: United KingdomPosts: 38 |
OK-Read the old posts. Its a big job for a newbie like me there's a lot of them. As a newbie much as I admire this site and the clever work done on it I don't understand the site. Everyone seems dedicated to Hawts and yet reading the earlier posts it seems a lot of you from the early days of the site started with Vawts and were getting good results (where results are reported ) and then you all stopped and swore by Hawts. Did the Bodysnatchers invade ? As you know I'm long on mouth and short on theory and even shorter on experience (to quote my wife ) but I'm doing all the research I can while logging wind. I must say the more I read the better Vawts look and I've already come across some pretty professional tests where they outshine equivalent GOOD hawts like the Proven range.(Glasgow Braehead extension ). When you add to that UK conditions like lack of wide open spaces , close neighbours ,planning restrictions it has to be a vawt at this stage of my research. You've even got a prominent article on the site about a Vawt in Townsville strand which self starts , makes no noise , produces good power , and is slow speed enough to plonk in the middle of pedestrians in town . What size insurance policy would I feel I needed to put a Hawt there ? And its practically underground no huge tower. On top of that little lot it spins at 90 rpm (whats the service interval ? 1000 years ?) and goes up to hurricane winds at a maximum of a massive 120rpm and keeps generating (presumably cutting the service interval to 800 years ? ) and as most of the early posts admit Vawts look so much better. I read most of the excellent and comprehensive Danish wind power site and can understand some of the many reasons for Hawts with big wind although even here the site seems almost neurotic about bearing problems. The other oddity about the site is that, educational and useful as it is about wind turbines(and it "acts" like an educational site)as far as a new reader is concerned there is only one type of wind turbine . I could n't find a reference to anything except Hawts. Maybe I.m the only guy the body snatchers have n't got . My wife was acting a bit strange last night but then they often do (Funny blokes , women ). I'm genuinely puzzled (but it don't take much ). When do I get promoted to "Disruptive Newbie ?" Big Al Every Day is a school day (even at 67) |
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Perry Senior Member  Joined: 19/11/2009 Location: Posts: 190 |
Hello Big Al, Can you post a link or two for these reports where the VAWT's are outshining the HAWT's? Take for instance the Windspire. The darling of the VAWT crowd http://windspireenergy.com/ It tout's everything you are hailing as the benefits of HAWT's. The usual canary's. No need for a tower, Doesn't have to yaw, safe for birds (that's total bs). Seems pretty credible. Now read the official test report from NREL which shows a complete gap between recorded data and spec's. The whole thing vibrated itself to death in a little over 4 months and couldn't even complete the test http://www.nrel.gov/wind/smallwind/mariah_power.html If VAWT's really did perform up to the levels of some of these claims all turbines would be VAWT's. It's not that we don't like them out of principal, because they are cool. It's just that there are better more reliable ways that most have gravitated towards. Perry |
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| VK4AYQ Guru  Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Rubes I had a look at your mill in the Photo and I think I know what the problem is for it not starting, The ones I made required a starter SV rotor to get them moving as while they are stationary they just waffle around in the wind not starting. I used a SV rotor on the top as that got them going, with later ones I made the SV rotor vane spring loaded so as it spun up they spun out into a cylinder shape to minimize high speed drag. I have made a few large ones years ago and found them very reliable and low maintainence, but lower overall power for frontal area than a HAWT, I will make another one as soon as I get some other projects out of the way, as I feel they have their place in the scheme of things. The ones I made where 3m dia and 6m high. They worked from 5 mph up. All the best Bob Foolin Around |
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| Big Al Newbie Joined: 06/10/2010 Location: United KingdomPosts: 38 |
Bob, I plan to build Vawt (unless as a heretic I get converted first ). Does SV stand for savonius ? I need a self starter and planned a retracting savonius like this (now comes the problem (despite a bit of coaching from Mac I have n't learned it yet ) but if I've copied it accurately the ref. should be youtube.com/watch?v=sCnq8tksgs8feature=more_related If it is n't sorry I've wasted your time but you should see a small disc with flaps that retract as they rotate under wind pressure. First thing that strikes me is it's pretty , clever , and minimises drag once the main rotor starts to lift. BUT I'm not sure it would start a big vawt ,looks full of accurately made parts (reliability ??) , and how tuff is it ? I want any vawt I build to still be running and generating when the wind is roaring and I'm not sure this little fellow would be strong enuff. Mind you he should be well retracted in winds that strong. I would certainly be interest in your retracting SV design if you could give me a ref. on the site.Rgds. Big Al Every Day is a school day (even at 67) |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Al Yes it is a savonius , which is a good low speed mill and starts in very low wind, I found that a SV at 1/3 the diameter of the main mill and equal height for diameter would start it if not loaded, I had a centrifical clutch to unload the main mill as any cogging in the generator will hold the mill stalled. On the next one I will make a AXFX alternator to avoid cogging and do away with the clutch. I used a swing vane in the SV to spin out to a drum shaped device once it got to 50 rpm, that was done with a pivot on the vane with a weighted arm that swung it out and a light spring to bring it in when it stopped. I will do a bit of a mud map later today and send it to you on the forum. All this was done 35 years ago and photos and plans I had where destroyed in a flood years ago. My interest has been rekindled in VAWT's as where I live now has a low wind speed most times and the HAWT aren't the answer for power in low wind, in saying that it is possible to get much more power from a HAWT when the wind is up. A VAWT has to be big to get useful power at low winds. As I said I will make another one when I get some other projects under control, I will post it on the forum for the general interest, and do a set of plans if there are enough people interested in having a go at it. On your flapping disks, I found anything that flaps and moves causes unwanted vibration in the mill and makes it noisy and causes it do fall to bits much quicker. Some members of the forum don't like VAWT mills because of their inefficiency, but to me its a case of horses for courses. All the best Bob Foolin Around |
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GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Bob, instead of the mechanical centrifugal swinging out of the SV rotor, I would just mount the SV on a sprague clutch. This would allow the main rotor to achieve a higher rpm without any balance issues with moving SV masses around. Gordon. become more energy aware |
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| Big Al Newbie Joined: 06/10/2010 Location: United KingdomPosts: 38 |
Gordon, Could n't find Sprague clutch in a quick Wikipedia scan. Is this ball bearings in a tapered track to give a ratchet effect ? If so I like except for a few concerns about maintaining balance. We don't have F&Ps in the uk so cogging not a major worry. In the UK we usually have adjacent neighbours and smaller plots , which gives Vawts definite advantages in factors such as noise , aesthetics , and neighbour impalement due to departing blades , which by and large they do not welcome. I anticipate a vawt will be much more difficult to balance dynamically as its moment of inertia is "spread out " along its axis but against that balance probably matters a bit less due to its capacity for bigger and more bearings without impeding the wind path. The space under the bottom bearing also allows for all sorts of clever devices (variable pitch-probably not a runner- ,centrifugally adding moment of inertia as power builds (balance problem ??).etc without impeding flow ;but anything added here has to be simple enough or well engineered enough to be reliable for me. My enthusiasm is good at the design and build stages but falls off rapidly at the maintenance stage. I'm trying to build a mill , not a mill stone around my neck. Incidentally the fact that a Pelton wheel gives a fluid/ mechanical motion coupling without I think , being pinned down by Betz has given me a further idea for effective wind power. but at this stage I better keep this crazy idea quiet until I've got some experience and disillusionment under my belt. Many thanks your inputs. Currently I'm logging wind with a Power Predictor which will take about 3 months so I'm a long way off putting any money where my mouth is. As I've said elsewhere "I ain't building no water mill til I checked Ise got a river" . I'm not EVEN convinced hawts are more efficient in high winds and at least Vawts can keep motoring and producing power in the highest winds , and once I've improved my posting skills (with Macs tips )will upload a few references on this both practical and theoretical. Until then the Ropatec in Townsville Strand (this site ), does n't seem to be doing too badly and I don't think the Ropatec is even the best European vawt (its pretty good though ). Rgds. and thks. Big Al Every Day is a school day (even at 67) |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Gordon Very good suggestion on the sprague clutch, I did look into using one when I was building them, but at the time the cost was an issue, I think from memory they where $250 or so, at this time this would be like $1000 in today's dollars. The SV rotor on top of the VAWT makes no difference much to the output of the mill once it is going properly, but it does make it noisy once the SV is running faster than its wind sync speed, it makes a low frequency moan noise that is audible for a fair distance. The swinging vane SV was a compromise and isn't ideal I am first to agree, but it was a solution, as I am sure there are many more. I also tried running up the mill with an electric motor, that was a success also, it just required automation to fire it up when the wind starts up, and as the mill spins it turns into a generator and pumps back a bit of power. All the best Bob Foolin Around |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Big Al, My limited experience with VAWT (Lenz2) is this: widely separated top & bottom bearing are big trouble. No matter how stiff you make the bearing frame, there *is* the possibility for it to twist out of alignment. And a shaft with wind turbine vanes running out of alignment is asking for trouble. I would be worried with that flimsy looking set up further up this topic. Perhaps it was just done so for experimentation's sake. I have since gone to the single bearing hub idea with shortish (~600mm long) blades running a larger diameter 5 wing arrangement. Hub is just a modified trailer hub, very strong. Increasing the diameter does reduce the RPM on my set up, I overcome this with a 6.3 : 1 planetary gear box. It works, producing 24V cut in from about 60RPM. Still to do is increasing the wing size for more starting torque but leave them still only 600mm long. Many VAWT are skinny & tall, I would think the opposite (short & fat) is a better mechanical arrangement. Klaus |
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| Big Al Newbie Joined: 06/10/2010 Location: United KingdomPosts: 38 |
Klaus many thanks for i/p. I agree with every thing you wrote. Do you know what sort of o/p you are getting with Lenz and in what winds ? the Lenz to me looks like a combination of Savonius and Darieus and I think to get maximum o/p I need Maximum Darieus and minimum Savonius (once the basket starts lifting ). Incidentally the Ropatec (see Townsville Strand on this web site) is designed to run at 90rpm (good eh -think of the low maintenance , high safety , but perhaps a little less excitement and fun) and supposedly will still be running in hurricanes ,and producing power. Supposedly it does stir its bones and gets up to 120 rpm in hurricanes. I don't know if it uses gearing or a very clever generator but suspect its a very clever generator of large diameter (they've got the room )as its cut in speed is low and relability is supposed to be excellent. I think its an Italian design and my experience of Italian engineering is that its first class. Apart from maybe the best aesthetics the Italians can be masters at compact design at low cost. I have an Italian very low cost bandsaw with what looks like a tin blade .When you look at how it works you would say "Rubbish,they must have knocked this up for 10C" BUT it cuts beautifully and always runs and I never have to fix it. My target is an average 2.5 Kw per day from a 2 feet high by 4 feet diameter vawt (which would fit in with your"short and fat" thinking) from hopefully average wind speeds of 4.5 to 5 m/s (I'm still logging as I ain't building nuffin unless i've got 4.5) but will post progress.Rgds. Big Al Every Day is a school day (even at 67) |
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| Big Al Newbie Joined: 06/10/2010 Location: United KingdomPosts: 38 |
P.S. Its gearless-says so on Ropatecs data sheets. I never did understand the obsession with high speed .Torque needs higher capital cost but makes up for speed and cuts maintenance and adds safety. Big Al Every Day is a school day (even at 67) |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
An interesting note. Ropatec and many other VAWT's are rated for output at approx 15m/s, while most HAWT's are rated at 10m/s. Readers should carefully check any specs for a VAWT they intend to purchase. The windmill should be suited to the wind reigime at the location. Gordon. become more energy aware |
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| Big Al Newbie Joined: 06/10/2010 Location: United KingdomPosts: 38 |
Found Spague clutch on Wikipedia , Its listed as Sprag clutch This is exactly the sort of thing I had in mind ("ball bearings in a tapered track "). I was worried about balance with ball bearings "floating" in a tapered track but Wikipedia article labelled "Freewheel" shows a version where nothing floats and could be self built for not many bags of gold. Another altermative is a spiral wound spring which grips one way but slips the other way, rather like those rubber strip gadgets that help old folks like me open tight bottle tops , similar action and principle as a Stilson wrench.Reminds me of extracting bending springs. Twist one way the spiral opens up and grips , twist the other way the spiral tightens up , the spring gets smaller in diameter and out she comes. Point for me about the Rotapec is not how its rated but that it can produce 6Kw from a directly driven generator at 90RPM and presumably a lot more at 120rpm in a hurricane (when most of the small hawts are either airborne or shivering in a furled position ) I think its wind efficiency can be improved for any particular specific wind regime . The designers presumably have had to compromise in producing something that suits a lot of wind regimes to maximise sales. All the same and however its rated if Ropatec (and as far as I know they are pretty reputable) and the folks in Townville Strand are telling the truth here is a vawt doing all I would want , and to open the eyes of the hawters. BUT...... it ain't a ropatec type I got in mind. Still Reading the huge backlog of posts a newbie like me has to catch up on as I don't want to bother folks with questions alreasdy answered years ago on the site and I thought Vawt/Paul (was it?) was on a good track with his Savonius morphing to a Darieus but I think implementing his idea reliably and without significant mechanical losses would have taken a better man than me. I might have an idea on how his thinking could have been implemented in a simpler way but the geometries are complicated to visualise (not the build )and I would have to build a test rig to verify it could work. I got a lot to do as its not a Ropatec type or a Paul type I've really got in mind. Whatever I do eventually get I ain't going to buy it (not at UK prices,at my age I need a payback time of under a 1000years.) I'm going to build it so you guys will get the laughs I promised in my first post. Thought I would just be lazing around and laying low during the 3 months I'm logging wind and establishing what sort of wind regime I've got but its not working out that way.Rgds. Big Al Every Day is a school day (even at 67) |
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| Perry Senior Member Joined: 19/11/2009 Location: Posts: 190 |
Hey Big Al, Hopefully you take my comments as constructive. Not trying to convert anyone. Educate yes but convert, no. Regarding your above comment... I think you need to manage your expectations. a 2ft by 4 ft VAWT in 5 m/s wind is only going to put out about 15 watts. And that assumes that upwind half produces as much as your downwind half, which is generous. So the most you can hope for is about .35 kW-hr/day. And that's if the wind never stops once. I never trust a spec sheet from a small wind company (HAWT or VAWT). Primarily because there are no standards for them to certify against yet so they can say what they want with impunity. Look for independent tests. Here's one for the vaunted Rapotec test report Look at the price vs the performance. Double the price and 1/3 the performance of the Skystream (HAWT). These are accumulated energy figures not instantaneous power as well (very important). Underlying my position that the whole 'no need to yaw/accept wind from all directions/no need to furl) are canaries for gullible people that are unwilling to do the proper research. Not you in particular, but people through all levels of the industry. I still hear it perpetuated by professionals at wind conferences but I have never seen it backed up with data. When asked, none of the believers have seen data either. Acceleration advantages of roof mounting and great performance at ground level are just outright lies (strongly worded but that's my opinion). Don't concern yourself with operating during a hurricane either. Why build a feature into a turbine at great cost that will be used for .0001% of it's life? Seems like new guys that come on the board are all pumped up to build a VAWT to solve problems that don't really exist. Me, I just want to build one because I think they look cool but I am going into it with my expectations managed. Once again, not a flame at all, just my opinions offered for consideration. Perry |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Al, To help you with your decision, I have just run some numbers for windspeed data logged at my site for the last year. This would be a guide to what you need to record and process. I have a Davis weather station and I record with weatherlink 5.1. The station provides 10 minute average windspeeds and records these. I have prepared some data and graphs. graph 1 is the yearly logged 10min ave windspeed graph in m/s. 
I have then manually extracted all occurrences of each logged windspeed and recorded the occurrrence for each. 
graph 2 is the plot of the windspeed distribution. 
On the matter of the occurrunce of high winds. in the last year, my location which I would classify as OK only for wind, recorded only 1, 10min period in 55000 recorded [0.0018%] during the year of wind with an average of 15m/s, and only about 100, 10min periods in 55000 where the windspeed averaged over 10m/s. look at the tail on the graph above. Once you have the windspeed distribution, you can design the windmill for it. There is not much point in designing for the big numbers if they don't occur very often. At my location, wind gusts are approx twice the speed of the 10min ave speed, these would need to be considered in a design. Gordon. become more energy aware |
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| Big Al Newbie Joined: 06/10/2010 Location: United KingdomPosts: 38 |
Gordon/Perry . Many thanks your very valuable inputs , esp to Gordon for spending some time for digging out his measurements and giving me an idea of what I need to measure. I think the Power Predictor information I'm Logging will enable me to do this and also give me info. on logged wind direction. Once I improve my posting skills I will post pictures of my site which will partly explain why if ,at all possible , I have to go Vawt. However it would certainly not be worth building for average o/p 15W although I might still be tempted for the fun. Looks as if I'm going to have to go bigger (not impossible ) or Hawt. Thanks also ,Perry. I was aware most of data untrustworthy but admit I did tend to trust some of the more reputable Manufacturers. (fool !!!).I read the test report and some of the later results and also the British Warwick wind trials. What an industry !!Riddled with false, optimistic claims aimed at burying deep into my wallet!!! Anyway the wallet is safe as I don't intend buying I intend building. So cost/Kw is not a very relevant factor. Even so the performance of the Skystream is staggeringly good . Can they really be that far ahead of not just all the vawts but also the other hawts ? Most of which were worse than the Rotapec . However that comment I might modify when I have worked out wind interception areas etc. The test also got quite a bit of criticism from neutral parties for various reasons which I will try and look into. The other thing becoming clear is that IF...I build a Vawt I will have to be not just smart , but also lucky , and will need helpful inputs from you experienced guys. Thank-you again. Will probably post a longer ( and more insulting to you colonials  ) post when I have re read , learned and inwardly digested the information.
And an apology my post earlier should have read to the effect I.m hoping to get 2.5 Kw per day from 2 METRES high by 4 METRES dia. not Feet . Trouble with being at theory stage still -mixed up my units. Taking Perry's 15W times 9 = 135W which over 24 hours gives 3.24 Kwhr. . Maybe hope lives again !! But its still going to be difficult , maybe impossible. ( Pity I had n't built something giving 2.5 KWhr per day from a 2 feet by 4 feet dia. Vawt . I'd have had a few of you beating a path to my door!!!) Rgds. Big Al Every Day is a school day (even at 67) |
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