High Power, High Wind, Small Size Windmill

[Aule Mar]

I have been following several of the windmill designs here, but haven't seen anything like what I want to build. It seems to be an area that there hasn't been much interest in.  I know that the power of the wind increases exponentially with the wind speed, and that most folks want there mills to start generating power at a wind speed of about 2-3 mph.  I'm interested in a wind mill that may not start producing power unless the winds are at 20-30 mph, but that holds together in winds of 80-100 mph.  I want to pull power from winter storms where the average wind speed is 50-60 Mph,  and then dump that power (several kilowatts) directly into heating elements to augment my home heating.  Since its going directly into heating elements I don't have to rectify it, or condition it in any way.  With a high wind velocity, I'm guessing that blade diameter of 5-6 ft might do.  I also don't care how much noise it makes, because when it starts spinning the winds will already be howling up a storm.  Has anyone ever considered this type of design or had any experience with it.  I know it will have to be very a beefy design to withstand the winds that I want to operate in.  Not really interested in any specific design info help now, just the feasibility, if its ever been before, and possibly getting discussion line started.

Aule

[zubbly]

hi Aule Mar!

i don't wish to stick my neck out too far, but i think it may be possible to get close to what you are looking for. (i may be totally wrong also as i have never gone to the extent that you ask)

3. phase motor conversions i have found seem to be able to handle output with no signs of overheating to date. i have a 1.5hp conversion that has done just over 2kw on a few occasions. inspections have shown no heating to date.
   
80. -100mph may be quite a different story. the thoughts in my mind now would be to convert a 5 hp motor. remove the laminations and re-install just 2 inches thick of the original and skew them. i would suggest using the 2x1x1/2 inch mags and drill and taper the hole for 1/4 by 20 tappered head bolt (stainless). remove the rotor laminations, and press on a solid steel blank with 12 flats machined on it (for a 12 pole unit).
    
    

design the winding for the cut in speed to be at the 20-30 mph wind that you wish. the 5 hp stator slots are quite large and will allow you to use magnet wire or combination of in the much higher circular mill area. high cut in speed (what ever voltage you wish) and the large stator slots should give you a good shot at a winding that will take abuse.

the 5hp frame, shaft, and bearings will hopefully hold up under those harsh conditions.

just my thoughts and do not reguard them as a solution.

a prop that will hold up under 80-100 mph winds?  good luck!  

zubbly

[Flux]

I think that will be something of a challenge and you may have to be content to let the power fall off with some form of furling or stall limitation in the higher winds.

Even with a 6 ft machine I think it will be a tall order to try and extract full power in winds up to 100mph.

You may reasonably manage it to 50 to 60 mph. Even with a tsr of 5 you will have a speed of over 1300 rpm at 60 mph. Even if you can live with the noise, blade erosion and other things become a significant problem.

Thrust loading on the tower will be a big issue and also to produce an alternator to handle a continuous 7kW output at below 1500 rpm will mean a large and heavy beast.

To take this to higher winds will be a really serious challenge. You would likely do better to be modest and perhaps limit the output in winds above 50 mph. You must be in a seriously windy area if you get these winds often enough to be worth thinking about. Most places only get these for a few hours a year and although the peak power is large, the average power produced is not that great.

Flux

[Infinity Steel]

Flux,what if one built a rotary mill,and used heavy aluminum blades? Metal blades would overcome the worst of the erosion problems. And be easier to replace,just bolt on replacements,rather than an entire prop.

A rotary, with magnets inside of a cylindrical housing, would be less suceptible to flying apart under high rpms. As well, a rotary can be built with multiple magnet and coil sets in the same housing-increasing power output exponentially.........

 Normally,the magnet drag would be a downside-but in the sorts of torque settings the guy is speaking of-hardly an issue..........Of course,it would have to be massively overbuilt to stand the strains.........

 But it's an interesting thought-the place I'm moving to in the fall has winds such as he describes quite often.

[vawtman]

Hi Aule Mar,

  I often thought about an hbar(vawt)that you could adjust the diameter according to daily wind speed projections.You could run it at 6x6 on calm days and since its close to the ground you could extend the rotor in higher winds.Just slide it out and pin it.Has the diameter increases rpms go down and torque increases.

 Im in the process of installing a 5hp conversion on my turbine and will use elements.Turning by hand warms one element.

  Since youre running elements you may need to devise a way get things turning before introducing the load.Im working on that.

  Just an opinion from a vawy guy.

[Nando]

Come ON guys !!!. think out of the box.

This is the exact case for an Induction motor converted to a generator.

12 poles 3 phase, 240 Vac.

And the use of a Pitch controlled 3 blades mill with stainless steel edge.

In the Patagonia area there are/were 2 of those wind mills producing 5 KWs each, about 6 years ago, I lost contact with the fellow I helped then.

The capacitors were adjusted on the fly to keep up with the RPM.

3 phase via with a simple MPPT controller for 9 loads, ( 3 pwm) and 6 ON/OFF.

Heating energy and electrical energy.

If I remember right 5 KW @ 18 m/s ( 22 m/s ?) and pitching starting around there.

Or using a induction motor with multiplier for lower Blade RPM.

Or getting the standard PTO driven generator around 200 RPM with AVR control.

( this last one, an Englishman and I are installing to a 5 meters 3 blades mill for heating purposes).

Nando

[Infinity Steel]

What was the motor conversion Nando?

And how was the resistor adjusted? Tied into a tach?

[asheets]

I want to jump in here and not that perhaps the biggest challenge is not the generator itself in this case, but getting the assembly to stay together while generating at 100kts.

I know most of the rig designs posted on the board (especially the Dans) can handle high winds but furl (or otherwise fail, if you look back at some of their earlier design pages ) at high wind speeds.  

I'm also reminded, having had to go back through some of my old meteorology notes for another project, that the high-speed, gust measuring aerovane over at NCAR's Table Mesa lab regularly fails at around 100kts -- and this is a machine that is supposedly designed to survive such mal-treatment.

[vawtman]

Nando,Why bother with all these hitech gadgets for a simple wind turbine?Seems more failures would be inevitable.Im happy with just using 2 leads of my 3ph conversion to elements in a standard water heater.Sure it wont bust betts law but will produce heat at low rpms.

 It seems other members have been struggling with driving heating elements.Im going to try to keep things simple and go from there.Could we custom wind a 3ph motor to fire single phase elements without using 3 in delta?Been buggin me.Zubbly any ideas if you see this?

[Nando]

The only thing done, a couple of small magnets in the stator to insure enough remnant magnetic field in the cse.

C & 2C capacitor arrangement to the 3 phase motor to convert to a generator.

An ELC heater controller with MPPT, simple.

A Pitch Torque controller

Simple design and NOT high tech.

Nando

[Nando]

Why do you run to say high tech gadgets ?.

YOU MAY BE HAPPY with your arrangement .. So be it, somebody else will say that your arrangement is not good enough for him -- It may be too poor in harvesting energy -- for one, this design is not a custom design, just using standard motors available in the market.-- no special builds

One needs to define solutions and their benefits.

This was a simple set up Where the so called Gadgets were simple ways to solve the needed problem and any other solution would have been a high maintenance arrangement.

Why are people always scared of simple things and call them high tech.

The controller was just a voltage detector that PWM a main load and when the main load was 100 or 0 % switched ON/OFF one load in each phase to maintain generator balance and proper loading with up to 2 steps.

It had a loop to behave with MPPT loading to improve the harvesting.

simple logic that is not high tech -- only high tech for those that can not attain electronic circuits.

Nando

[TomW]

Nano;

Why are people always scared of simple things and call them high tech.

Maybe its because you toss around terms many of the folks here do not understand?

I have my opinion why but I will keep it to myself.

Try understanding that many of these folks will NOT know WTF you mean when you toss out 5 or 6 acronyms in one comment.

Some folks need to be struck with a BFH just to clear their heads. Is That a

Basic Frequency Handler?

or a

Big Freaking Hammer?

See what I mean?

Just what is apparent to me.

T

[Countryboy]

I'm interested in a wind mill that may not start producing power unless the winds are at 20-30 mph, but that holds together in winds of 80-100 mph.  I want to pull power from winter storms where the average wind speed is 50-60 Mph,

Average wind speed of 50-60 MPH?  Yikes?  Where exactly in the world do you have average windspeeds of 50-60 MPH?  And exactly how often during the winter do you have such storms?

Odds are, storms with these windspeeds will be few and far between.  In the meantime, your windmill sits idle, making little power.  Odds are, you will extract a far greater total power by using a mill designed for lower windspeeds, and turning that mill off in storms with strong winds.

If you REALLY insist on building a mill that can handle high winds, build a Savonious out of oil barrels.  They turn too slow to get much power out of them in low wind speeds, but they'd be great in high wind areas.  You could also consider a Savonious driving a geared alternator.  You could select a different gear ratio for low winds, or for high winds.

[kamikaze]

Hi Aule Mar,

I am working on a design of hawt wind turbine which, although it will start producing power in relatively light winds, will continue to produce power in gale force winds, when other turbines will have furled/shut down.

Of course it's possible to design a machine as you described. My machine has 6 blades ( the blades have a curved sweep back) a low tsr/high torque, and have pitch control via an overspeed governor. Once the turbine hits 100% rpm, any increase in windspeed results in an increased blade pitch angle to maintain 100% rpm. The governor will maintain the rpm regardless of how strong the wind is.

100 mph? No problem! But of course the design has to be very good, and the components strong enough to withstand the forces involved.

By having a relatively low maximum rpm (say 500 rpm) the problems of leading edge erosion and excessive noise, and high centrifugal forces are reduced.

I also incorporate a gust relief feature which allows the blades to coarsen (partially feather) against spring pressure when a sudden gust is experienced and the overspeed controller can't react fast enough ie. at rpm's below maximum governing. Therefore the horizontal forces on the turbine and pole can never be excessive.

Another benefit of overspeed pitch governing is that if you suddenly had a generator failure or other electrical malfunction, the turbine will quite happily freewheel at it's maximum governing rpm - no sudden self destruction.

But what if the overspeed governor should fail?. I'm designing a simple emergency brake( spring loaded) which will activate for excessive overspeeds, and excessive imbalances ( eg damage), which will stop the unit rotating within a few revolutions and prevent further damage.

Sorry I can't include pics yet as the unit is dismantled while I am fitting new moulded epoxy composite blades.

Finally I have to agree with Nando, we should try to think outside the square a bit more. Just as well the Wright Brothers did't read some of the posts on this subject. They might have given up before they started, as their machine would surely fall apart and destruct at 50 or 60 mph. Incredibly within a short few years people were designing flying machines that could operate at airspeeds of hundreds of mph,capable of withstanding considerable g forces, severe turbulence, and in some cases withstand being shot at. And some were made of aluminium!

Regards Kamikaze

[finnsawyer]

M. Jacobs claimed his wind mills could withstand and operate in 100 mph winds.  You might check out his original designs.  You may even be able to buy one.

"Pressure matters".

[Phil Timmons]

The 100 mph windmill seems like a neat toy idea.  

I must confess, I was pondering this a couple of days ago, myself.

And was wondering if you could intentionally "hit" a hurricane with such a device.

I guess where I was drifting in concept with it not "daily use," or any concern about average wind, etc. . .  I follow many of the points about average wind, vs. peak winds and all, but I think the applications of such a toy are to just harvest the serious peak winds.  My bias would be to put the power onto the grid ($$$) rather than trying to doing sensible homeuse things like battery charging or even any direct use.

I was pondering that you might not even want to use a tower.  Maybe some reconfigurable lifting body.  (there are some lifting balloon or gliders that would work) and expose only the amount of wing surface to lift the device on heavy (heavy, heavy) cable.  If things get too wild, and the lifting body wings fold in and it drops right down to the ground.

The math ($$$) was not real favorable in my ponderings.  Even if it were around 100 HP, (746 watts/HP X 100 HP = about 75kW) you would probably only get about 10 hours run time in any give storm time per month (less in most areas).  So for 750kW hours (around $75) it did not really seem worth the effort.

[scottsAI]

Hello Aule mar,

Interesting responses to your request. Not too much helpful data.

What you want to do has been done. Read about it back... a while ago:)

Used on the arctic expeditions. 2 maybe 3 foot blade design.

The wind at 100mph is not a problem.

Prop driven airplanes use speeds far in excess of this.

So, a prop can be made. Two blade may be strongest.

Even using wood. Metal leading edges, snow and ice are very abrasive.

Several designs for a 10kw generator exist or get one for a 1800rpm generator, may be the easiest.

Have fun,

Scott.

[Aule Mar]

Will try to answer some of the questions that came up here, and give some more of my thought. I live in Frederick, Maryland, just east of Camp David but down wind of a pass through the Cotctin mountains.  We usually get 5-6 storms like that each winter.  My house is insulated enough that I don't have to heat until the outside temp is below 32 degs.  Its when the winter storms come in with the winds that I need the extra heat.  As for a generator I thought of using a standard 110/200 commercial generator head, I have a 5kw one I purchased for $250.00, sold by harbor freight. It puts out 110/220 V at 3600 RPM.  I'm more interested in how to design the blades to generate the torque needed to generate the 5kw, at 3600 Rpm.  I understand that the voltage will vary with rpm. But like I said earlier I'm just planning on dumping it into resistance heaters.  My thoughts are to switch in or out of circuit heating elements to match the power being generated.  I have a dozen baseboard heating elements in three different wattages, Figured I mix and match to actually absorb the power generated. I'm just in the conceptual design phase now.

Thanks for all the comments so far.