Bill's Super VAWT and Gen...

[fcfcfc]

The  Goal:

Extract as much electrical energy from the current location using wind and solar.

Provide automatic backup power in power failures for three days.

Integrate with the current residential living structure but have the systems in place on the new barn.

Have system grid tied to export excess power to the grid.

Provide all electrical energy for the new barn.

Site analysis:

The current site, from a wind perspective, has very little. The bulk of the wind occurs in the heating season months. It is "bursty" and turbulent in nature. The location is down in a shallow valley among corn fields and scattered trees and houses. The location is fairly sunny following the typical sun patterns of central PA. The available wind runs counter to the available sun seasonally.

Current available equipment etc..:

HAWT's would not work very well unless placed very high (over 75'). I view this as not cost effective and aesthetically un-desirable as well as too electrically inviting. I have has my share of lightning issues. The challenge is too design a turbine and gen using home brew types of construction. I have designed an axial gen that is a re-engineering of the current designs out there. I have created a design that I believe will be very efficient and be able to generate cut in voltage (48VDC) at around 30 RPM. The turbine I am designing is a VAWT. I chose this for its ability to "take" wind automatically, without adjustment, from any direction, roof top mounted as well, and a good balance between lift and drag. The current VAWT designs out there to date are many, but I could not find one that had the right "mix" of lift and drag that I was looking for and was very strong and fairly easy to design and build. I also wanted a 5KW burst capability (under 40MPH winds), so it was not going to be small as allot of the VAWT's out there. The system will be tied to a 48VDC battery bank which will have a 6KW grid tied inverter hooked to it. The inverter will run in "blocks" of time based on a top "kick in" battery bank voltage and run down to a "kick off" battery bank voltage. This will accomplish two things. The inverter will run in relatively big chunks of time and the battery bank will gather energy as soon as the gen voltage "cracks" over 48VDC without any sync issues or delays for same. As a side note, more than 50% of the time when we have power failures, high winds are the cause or are present at the time of failure. This will most likely mean the system will actually be generating substantial amounts of power during a power failure, when it is most needed. The system also has to be able to accept PV power additions later in the future, without overly complicated connection equipment, use the existing wind infrastructure.

Generator Design etc..:

Previous links relevant to this;

http://www.fieldlines.com/story/2007/11/30/0312/9434

http://www.fieldlines.com/story/2007/12/7/232131/157

http://www.fieldlines.com/story/2008/2/25/24459/4156

http://www.fieldlines.com/story/2008/3/3/213428/1577

These are the most useful posts of all of them. Some of the others get a bit dicey..

Anyway, the design went through many changes in my head. Originally I was after a very high voltage for a direct connect to a grid tied inverter. But, I then began from scratch thinking about the site. What kind of wind do I have?? How does it blow most of the time?? Etc.. When I looked at the direct connect inverters for PV and wind, I noticed that there were time delay issues with getting the gen "sync'ed" to the grid, lasting a few seconds usually. That delay in low bursty winds would mean that a worthwhile portion of the available energy at those levels would not be gathered, being wasted by the inverter trying to frequently sync up. Secondly, there were the peak power generation issues. What do you do in the case of those occasional high winds that would push the inverter over the edge? I am a firm believer in K.I.S.S. but I also want high efficiency in my designs. To put it simply, I want my cake and eat it too. Additionally, I wanted every watt possible no matter how small to be put into my KWH piggy bank... The solution was a direct connect to a medium sized battery bank with a low voltage grid tied inverter hooked to it, with the charge function disabled. This solved the inverter overload problem, beating up on the batteries instead, and the inverter would run in relatively big chunks of time, yet the gen energy would be captured instantly above cut in voltage at very low turbine RPM's, extracting even tiny amounts of energy. Also, in very high winds once the battery bank was full, the inverter would kick on pulling 6 KW from the batteries keeping them from over charging. Protecting the gen would be fairly easy using thermal snap disks in the stator tied to relays on the gen output. When the stator gets too hot, the snap disks close and open the normally closed relays, free wheeling the turbine. This has no effect on the inverter which is tied to the batteries, not the gen. Any power surges from the gen are buffered by the battery bank, protecting the inverter. In theory at least, it seems the best of all worlds with a fairly simple design. The only loss in the design is the leakage power loss from the batteries. This is why the bank does not want to be too big. The bigger the bank, the greater the leakage loss in total energy.

Target Min Energy Goal for Turbine/Gen Combo:

A rough target for the energy output for the completed wind turbine/gen system is as follows:

5. MPH =  2.235 ms        24 watts
   
7. MPH =   3.13 ms        66 watts
   
10. MPH =  4.47 ms       192 watts
    
15. MPH =   6.7 ms       647 watts
    
20. MPH =  8.94 ms      1536 watts
    
25. MPH = 11.17 ms      3000 watts
    
30. MPH = 13.41 ms      5187 watts
    
    

These numbers reflect a 35% energy extraction from the wind (Turbine efficiency) and a 75% gen efficiency (Electrical efficiency). Sweep area is 13.38m^2 (4' x 36').

Rectifier setup:

The rectifier heat sink and 6 - 1GBT's are shown below. There is not any particular engineering reason why this was the starting point in terms of real parts to the system. Just more of a function of spotting things and availability issues. The small full wave in the above center is a backup and is for emergency use only. Its terminals are connected  to each other for protection reasons. The 1BGT's gate and emitter terminals are shorted for the same reasons as per a suggestion on this forum.

(connections not made at time of photos)

Costs:

Heat sink:              57.50

Sold heat sinks:         (9.95)

6 - 1GBT's 1200V, 600A          106.25

Full wave 800V, 110A             14.00

S&H                 28.34

SS nuts/bolts/washers            19.06

End mill machining               35.00

            ------------------

                   $250.20

The heat sinks I sold were ones I thought I would use, but turned out to be too small. I have had them for over 10 years.

[ghurd]

Not an expert, but VAWT? You noticed how wind increases with height. The windy top area dragging the windless bottom area can't be good. Here, 35' between 8' and 42' is all or nothing. Three days of backup battery seems like a huge waste of power and money. Small battery sized for 6KW is an oxymoron. How many times in the last 10 years, or the life of the chosen battery bank, has the grid been down for 3 days, and what would the genny gas cost be to keep up with it. Freewheeling is not good, even with a VAWT. And there is no VAWT power available worth any worry in gusts. The target efficiency numbers are all messed up, and not remotely possible as far as I know. KISS, VAWT, and efficiency are not suited to each other in something like this.  Just my take on it.

G-

[fcfcfc]

Actually its 60' and 24'... just a bit lower than the 75' start height for an HAWT here... I believe the numbers for watt targets are correct unless you care to be more specific.. vague negatives are not much use I am afraid...

[spinningmagnets]

Dear Bill, If you could make a prototype PMA that makes 48 volts cut-in when it's spun at 30 RPM, that would be very useful, whether you end up happy with your VAWT design or not.

I'm not allowed to have a HAWT where I'm at, and frankly, I can't see any way to improve it. If I can move to the country someday, I will copy the otherpower HAWT exactly. This leaves VAWTs, which may have some room for improvement...

Windstuffnow.com Ed put a Lenz2 on his roof and got a small pic in Popular Mechanics(?), but I have heard that a house mount puts a vibrational buzz through the entire frame. I'm not saying it cant be fixed (I've seen large machinery sound-isolated from a ships hull) but I'm just letting you know ahead of time what you might be wrestling with.

I think VAWT's have some similarities with water wheels (Google cameroon water wheel). Since their water wheel had very significant torque, they decided to go with a large diameter/high-pole-count PMA (expensive) instead of gear-up.  

If the rim speed is about 90% of wind speed, you can calculate the diameter of the VAWT relative to average wind speeds at your site to get your target RPM's. The way then to add more torque is to make it taller to add more swept area. This can get very unwieldy. The Jay Leno VAWT was as tall as a 2-story building (dont remember the brand), and the direct-drive PMA had a fairly large diameter to get a decent magnet speed.

Another choice is to make a very large diameter VAWT (in order to increase swept area, but results in slow axle RPM's in the same wind speed) and use gearing to speed up the PMA, a completely different can of worms.

Once you've cruched the numbers, a tower and a HAWT start to look pretty good.

Sometimes a new blood pressure medication results in a profitable blood flow to other areas (Viagra) so your VAWT design exercise may result in some useful data even if it doesnt reach your particular goals. Best of luck!

[fcfcfc]

Thanks for the comments.... the gen will be in the 30" dia range using my blocking mag tech.. The diameter to height I believe will be right for the desired torque/RPM result. I have to do the wind tunnel tests... the design is my own and a bit different than what's out there... more on that after the WT tests in the fall. The VAWT will have a combination of an Aluminum exoskeleton and 4 guy wires. Its going to be on my new barn/warehouse so noises really don't matter much to me... will probably do some rubber dampening though... this is going to be a long project... probably 2-3 years till end...

[valterra]

Not sure what was vague about ghurd's reply.  His information was pretty specific and to the point.  The fact that you corrected his numbers about wind speed mean that you didn't read what he wrote.

Just my observation.

Not an expert either, but someone who graduated from doing it on paper to doing it in real life.  Two different scenarios.  Like you, I believe in KISS.  My system (like yours) was way more complicated when it still lived inside my head.  Reality strikes now and then.  Hopefully when you have those little flashes of genius in ingenuity that we all get whilst doing these projects, they won't occur after you've already sunken huge amounts of money into traveling down the wrong path.

Case in point - is there a point to grid-tying 24 watts?  I'd assume you'd lose nearly that amount in your rectifier assembly.  Routing everything through bridges and grid-tie equip and inverters just flat out doesn't work well with low wattage, bursty generation.  Trust me, I know!

The considerations about the delays involves with grid interconnects is very valid.  Like you, I want to extract everything I possibly can out of the wind and sun.  Even on cloudy, "windless" days.  That's why all my stuff is tied directly to BATTERIES through diodes.  On cloudy days, I make under 10 watts.  During storms, I've made over 100.  My wind is fickle like yours.  It bursts.  And those gusts are almost nearly useless.  These machines we build take time to build up to speed.  Inertia.  If they're made to spin too easily, then they are low power producers.  If they are big producers, they take more wind to start.

Don't just cherry-pick a few non-"dicey" posts on here and run full-speed-ahead with your wallet hanging out.  Trust me.  When any of the "regulars" on here start to poo-poo an idea, it's not because they're jerks.  They really want to help people.

So far, at 8c / kwH, you're over 3,127 kilowatt/hours into this project.  I'd like to see anyone who's made an VAWT that has produced 3,127,000 (3.127 MILLION) watt-hours in a location where there is no "good" wind.  Now, I'm not saying that our RE projects are all profitable.  Nor am I saying that the "experts" are always right.  (Hugh Piggott makes a big deal about how there's no wind on roof-tops.  Well, Hugh's never been to MY house.)  

It's fun to tinker in this stuff, but if you want to K.I.S.S, then seriously look at:

• How often does the power really go out?
  
• Will a turbine that produces good power at 5mph survive a thunderstorm when the power is out?
  
• Does your whole house need to operate during a grid outtage?  My next goal is keeping my refrigerator and freezer going.  That's on top of the radios and lights and misc other things (12vdc (simple)) that currently run if the power goes out.   Everything else can wait until they fix the power.
  
• Will you waste more energy charging batteries to power your loads during "on-grid" days than you will generate during windy days?
  
  

I'm not trying to come down on you, brotha.  :-)   This is coming from someone who's had to step out of his head and all the theory and "good ideas" and realize that there is a REASON the guys on this board have specific methods that are "Tried and True."

Like ghurd said, "KISS, VAWT, and efficiency are not suited to each other in something like this."  I'm way behind the big boys on this board, but light-years ahead of those who've never done it.  And I can tell you that you're already way more complicated than my setup, and you're not even to the generating stage yet.

Again, not a flame.  I just don't want you to get too far down this road ($$$) before you think of a simpler way to do it.

[wooferhound]

I think you should put a small model of your VAWT up in the location that you intend to build the Big One at. You don't need a generator, just a VAWT prop. Observe what your model does and evaluate your design & the wind conditions at that site. This will show you what is possible way better than any Talk can do.

[CmeBREW]

Hi Bill,

         Awesome heatsink. Your wind area sounds a lot like my own. I have my prototype Lenz vawt right beside my 7' hawt, and I find that stop and go turbulance affects them both about the same.  

I second the prototype idea, because you can make countless alterations quicker, easier, and cheaper with the prototype. I know I have made countless changes with mine. It is also quite discouraging output. They go very slow rpm which limits many things.  

Your alternator sounds very interesting.

Good luck and we're looking forward to your progression.

[finnsawyer]

Typically, an alternator putting out 24 watts at 5 mph will only put out about 150 watts at 30 mph.  If you design instead for 66 watts at 7 mph, you would get around 280 watts at 30 mph.  Unless you over design the alternator to provide 5,000 watts at thirty mph and then use some means to reduce the alternator output at every other mph to follow the power curve of the VAWT you are apt to be disappointed.  Have you considered that issue?

[vawtman]

Hi Bill

 How are you going to do wind tunnel tests?

[fcfcfc]

Hi V:

Thanks for the comments... the numbers I corrected him on were the height of the turbine off the ground not wind speeds....

The posts were my posts that I picked regarding a particular magnet idea I had to increase field intensity in the coil travel area.

I bought a good flux meter, got some magnets and did some arrangements and the idea worked rather well, though I do not look forward to building a gen with a ~30" dia and the magnet forces that will be in play...

You have to understand my goals. First it is not ROI driven. Like the purchase of the big screen TV which has NO ROI, I am doing it for other reasons. I want quiet power production with the energy from non hydrocarbon sources. I want 220-240VAC output for the running of the well pump. No water and you are pretty much out of the house after you have used up your 5 gal Well-X-Trol capacity. You can rain barrel the toilets but the shower is an issue. Anyway, its just the basics I am looking to run for 3 days, fridge, freezer, well pump, computer, TV, lights etc... not looking to dry clothes in the electric dryer or cook a meal on the electric range. Microwave will do.... The size of this turbine should lend itself to 500+watt power allot of the time... I am going to put the turbine up without the gen at first. It will be erected in three 12' sections (tot 36'). Each section build will be run for a period of time to evaluate all the mechanical functioning. The gen will be added last.

The turbine/gen will be connected through rect/diodes if you wish, directly to batteries. The inverter only runs when the batteries reach full charge, say around 51VDC. I will let them run down to around 47VDC (11.75 per bat) then the inverter turns off. The idea is to send to the grid but don't take the batteries down too much in case a power failure hits right after an inverter "run". The three day run time does include power that may be had from the sun and wind over those three days, so the battery bank will not be huge. One challenge is to try and find battery types that can be beat up on regarding charging voltages and current yet have a low loss rate in a state of charge. There seems to be an inverse relationship between those two attributes. As an example, Edison cells can be beat to death and still keep on ticking but they have a high loss rate. AGM/gell hold charges very well but are more sensitive to the charging parameters..... etc... I will probably do flooded LA's for cost reasons and charging toughness...

I pay just about 11c a KWH, at $250.00 that's 2272KWH... but that is really a non issue sense the total cost will probably hit 7 to 8K$ with inverter, batteries, neos, copper, etc, etc... as I said, its not about ROI....

[fcfcfc]

I don't want say exactly (by name) yet, but I believe I will be "linking" with a university for a project type of structure. It is not a sure thing but looks pretty good so far.... If it goes through, I will revile turbine details etc.. in the Fall or Spring 09...

[fcfcfc]

Hi: So far, I have designed the alt to handle the high end from a watts perspective. 5 in hand #16 will probably be the wire of choice for flex reasons. The power curve for the gen will not be had until I start prototyping coils in the rotors. My idea is to have the cut in at 30 rpm and charge the batteries un regulated. If the power becomes so high, like in a storm, the inverter will kick on when the 51VDC appears across the bank, preventing excessive over charging or over voltage. I hope to tweak this by battery size and "real" gen output once up. There will be allot of prototyping going on here through the process, I am sure....

[ghurd]

Finn covered the alternator numbers.

I'm not sure about VAWTs or the design you intend to use, but my understanding is the TSR (or at least RPM) is going to change non-linear with wind speed and load.

The top half is still going to be dragging the bottom half around, even at 60' to 24'.  

If a HAWT 75' up is not cost effective, run the designs, math and costs of a 60' tower holding a 4'x36' heavy freewheeling spinny thing with not many proper places for guy wires.  If a HAWT has to be over 75' to be effective, then a VAWT effectively at 42' can't be very good.

If a HAWT won't start until 75', there is no usable wind at 60'.

I won't even touch on the roof top mounting plan.

The gusts.  Not sure where to start. Valterra's blade set weighs like a pound and a half?  And he gets nothing measurable out a gust.  A VAWT of these proportions is going to have some serious weight.  I do not believe weight is an issue for output, just for the inertia and gust thing.

Not poo-pooing.  But you seem to have pulled random numbers to mix apples and oranges for the end results you wanted to get when you started.  You skipped over some very basic problems to get those numbers.

Might shoot for the elusive model that makes 100W, before going 52 times larger.

[fcfcfc]

Hi V: The output watts were simply using the standard equation:

P = 0.5 x rho x A x Cp x V^3 x Ng x Nb

where:

P = power in watts (746 watts = 1 hp) (1,000 watts = 1 kilowatt)

rho = air density (about 1.225 kg/m3 at sea level, less higher up)

A = rotor swept area, exposed to the wind (m2)

Cp = Coefficient of performance (.59 {Betz limit} is the maximum theoretically possible, .35 for a good design)

V = wind speed in meters/sec (20 mph = 9 m/s)

Ng = generator efficiency (50% for car alternator, 80% or possibly more for a permanent magnet generator or grid-connected induction generator)

Nb = gearbox/bearings efficiency (depends, could be as high as 95% if good)

I used 35% for the turbine and 75% for the neo gen... It is just a starting point for a maximum power design point... I use 5KW as a max continuous condition and used the power wind targets as a ballpark for the possible speeds those watts may show themselves. Again, cost effectiveness here is not real important. If I can afford it, I will do it. I just do not want a 100' HAWT in my yard on a tower for allot of reasons. If I lived on a farm, it would be different... My VAWT can at least be worked into the building to some extent....

Thanks for all you comments... I will continue to post as each part comes to be...

[electrondady1]

hello ,

i must admit i didn't read all the links but i recall some of your previous posts

as they were on a subject i am interested in.

if memory serves me correctly i was under the impression you were going to run a horizontal vertical along the peak of your barn.

is that correct?

the alternator you have envisioned is very interesting and i hope it will work out for you.

i'm impressed and envious of anyone who has there own Gauss meter !!

if you build the impeller section as you have described you will be sweeping about

90 sq.ft.

the equivalent of an 11 ft. dia. hawt

there are those on the forum who can tell you exactly what one of those

 may  generate .

how do your predicted output figures compare ?

depending on the design of your mill,

shouldn't they be about half?

[electrondady1]

don't want to give the wrong impression.

what ever the output or efficiency,

to me the most important thing is  actively trying to improve your situation.

 hey, good luck with it.

[ghurd]

I know the numbers.

You ignore Mr. Ohm and Mr. Watt.

Like you say, it is your money.

[fcfcfc]

Unless I am totally off base here, I think the sweep area of a VAWT that would somewhat resemble a savonius design, is simply the width x the height, 4' x 36' = 144SQFT I believe...??... Its just I am erecting it in three sections 12' high by 4' wide each, total 36' high and 4' wide... about equal to in sweep to a 13.75' HAWT..

[ghurd]

How about...

My wife's car gets 0 MPG, running, in park.

My truck gets infinite MPG when not running and pushed down a 5 mile long hill.

Infinite or 0 MPG?

My truck obviously gets better MPG than her car.

And the combined average is (Everything + Nothing)2, or half of everything?

So 0.5 X infinite.

Therefore we used all the matter in the universe, or spend no money on gas.

That is not true, so we should pick some number.

And 40MPG is a good for an efficient car. My more powerful truck gets better MPG than her car.  

Math says something like {(0.5>40) + (infinity/2)}/2 = truck MPG?

That is about where you started.

Tweaking the battery is of no consequence.

The ""real" gen output" is what you don't understand, at all.

[vawtman]

Please keep your cape tucked in until then.

[valterra]

On my next trip to work, I will try to remember to take spme pictures of a 30+ foot tall "ginormous" VAWT out in rural nebraska.  I'm sure, when spinning, it could power a large hotel.

No joke.  

It is the biggest RE thing I've ever seen, except for the HAWT blades they ship via rail that come through my yard.

It almost looks like a carousel.  From space (google earth) it looks like a big asterisk.

Anyhow, the wind blows almost non stop here in the plains.  Nothing to slow it down for miles and miles.  This thing is a good solid 25 miles from the nearest metropolitan area surrounded by corn fields and the occasional house.

Wind blows all the time.  It's completely ridiclulous sometimes.  This is a "good" wind area.

Never seen it budge.

But his anemometer seems to work okay.

Your results may vary.

[DamonHD]

Can you post a Google Maps link?

Rgds

Damon

[electrondady1]

sorry i was using a 30" dia.

yes , 144 sq ft.

that's about half of what danb"s 20 footer sweeps

he is on top of a mountan 90' up .

you are in a valley close to the ground.

unless a person is willing to move to a new location.

we have to use the wind available to us .

if your wind mill performs as expected then great.

if not then put up more swept area.

in low winds a sailboat can put on more sail .

the modular aspect of your design may come in handy .

[fcfcfc]

Hi..

Well, I hope you are right, otherwise you will be eating a whole lot of that preverbal black bird.... with such positive thinking and helpful comments...

[fcfcfc]

LOL!!! my cape is being laundered due to excessive _hit from Ghurd...

[fcfcfc]

Hi: That's funny... really...

If you have seen the windspire:

http://mariahpower.com/index.php?option=com_content&task=view&id=13&Itemid=35

it is almost as tall as mine will be, just at half the width... I think there power advertised is just a tad over rated.....

Anyway, it is similar to my design, at least in its aspect ratio.. theirs is 15 to 1, mine is 9 to 1.

Again, I will wait for the WT tests... the turbine concept may turn out to be great or a total flop... or somewhere in between... I don't know.....

[vawtman]

Zubbly(r.i.p.) used flux spray on his cape for better performance.Not sure how it would work on stains though