Author Topic: Prairie Turbines (Read 4294 times)

tljones · « **on:** February 22, 2007, 04:35:24 AM »

Understand that I am not an engineer before I start.... I am a biologist.

What am I missing when I look at this thing?

http://www.prairieturbines.com/index.htm

I did a search here on the board and it seems no one can come to any definitive answer about this. let me summarize where I am at.

I am living on a hill in the plains of SD, in a class three wind zone. I have turbine farms within a hundredmiles in any direction, and while that is not definitive the supply of moving air is not my main worry.

I am never going all the way offgrid. My family will never put up with me going that far. I am currently genereating from a little test genny on the roof into some 12v batteries and have been avidly reading every night for several hours what is possible and what is not. every time I think I have a handle on things something reaches up and smacks me. Last night I was looking at outback systems and princing what I would need to take my 110 volt circuits of grid and onto battery. Never mind if that is a good idea.

Now I find this and I am seriously wondering why in the world you would put a couple thousand bucks into controllers and generator when you could build this and maybe get to a break even on the grid??? I pay 8.5 now and can sell for a crappy 2.6,( REC guys were here today). I understand that this might not be the most elegant way of harvesting wind, but sometimes brute force and simplicity overwhelms engineering elegance. If I could build this for 5 grand I really see how I could have a no cost energy bill and pay it off in a few years!!!!

less elegant design, less efficient, more survivable, self regulating, and off te shelf. Plus no inverters or all of that jazz. I suppose as crazy as it sounds you could actually charge a battery storage bank for outages witha charger from the supply as well, but the real beauty is suplementing or replacing my grid costs without a day to day battery management chore. Build in a healthy service time budget and let it roll...

What am I missing guys.... I really need some help!!!!

Tom

tljones · « **Reply #1 on:** February 21, 2007, 09:38:51 PM »

Whoops.... that should say why would you spend thousands on controllers, batteries and inverters.....

Time for sleep, thanks all.

Tom

wooferhound · « **Reply #2 on:** February 22, 2007, 05:37:43 AM »

I could'nt find where they state the Blade diameter but using this picture I figure it is a 20 foot diameter 4 blade

And here is a picture of their Generator

Making the rough calculations on

Alton's Propeller Carving And Power Calculator

http://www.alton-moore.net/wind_calculations.html

I would say that the power levels are remotely possible

But then they talk about a 15 to 1 gearbox

and no batteries

then it gets hard to believe to me . . .

DanB · « **Reply #3 on:** February 22, 2007, 06:00:50 AM »

I believe it's an 18' machine. I expect it may workout fine...

Some of the the stuff on this page (the economics) seems optimistic to me:

http://www.prairieturbines.com/economics.htm

An average 15 mph wind is pretty uncommon I think.

They also have a production graph which indicates the machine makes over 1KW below 8mph and that it produces about 2.5 KW @ 10 mph. That's impossible I think by a big factor. 300 - 400 Watts in a 10mph wind might be more realistic if its a decent machine - not 2.5 KW.

I expect it might be a good solid design, but if people go into it believing the stuff on the economics page then I expect they'll be disapointed.

wdyasq · « **Reply #4 on:** February 22, 2007, 06:24:19 AM »

"I expect it might be a good solid design, but if people go into it believing the stuff on the economics page then I expect they'll be disapointed."

Dan,

Apparently you didn't get the note. The laws of physics have been suspended on the Internet. Overunity machines and impractical projects can now be constructed. Results can be posted to the Internet. They only have problems when subjected to real world observation.

Ron

DanB · « **Reply #5 on:** February 22, 2007, 06:33:35 AM »

Another comment -

you can use 'google search the board' (on the top right of things to do here) and youll see it's been discussed a fair amount here.

Again - I think it's probably a workable and economic design. I've seen their book and it's pretty detailed.

Reliability is a hard thing to say... a couple of machines of any type might seem to be very reliable, when lots and lots wind up in different places then problems might start showing up. I expect this one must stall it's blades to some degree to protect itself. The lack of any sort of other furling or governing system bothers me a bit.. but - I don't have experience with these, they might work out quite well! I do like the simplicity of the system if it works. It would not be useful for battery charging.

thefinis · « **Reply #6 on:** February 22, 2007, 06:57:28 AM »

I have been checking in on their progress for a year or two and it worries me that there are so few customer Breezy units up. It seems like a fairly workable design so why just a few units flying other than theirs? My guess is that either it is harder to build and erect than it looks or that the gridtie is causing snags. Sounds like they have been having trouble with their micro controller. I know that in Texas you might as well consider it two projects maybe three if you want to count the tower as a seperate proect. One is the turbine and generator, two is the tower, and three is the legal process and equipment to be able to gridtie.

I would try and talk to the guy that built one in Utah and see how he feels about it now. If the one in Texas gets finished I will try and check it out.

Finis

DanB · « **Reply #7 on:** February 22, 2007, 07:07:18 AM »

Yes, I know that in some places its a problem to hook something like that to the grid, if its grid tied it needs to be approved (probably UL listed or something). If thats the case, then it may be better to have an approved grid tie inverter between the wind turbine and the grid. I expect the 'windy boy inverter' is a really nice way to go - I'm dying to see someone setup a nice system with a homebrew axial flux machine and a windy boy inverter - it'd be neat.

tljones · « **Reply #8 on:** February 22, 2007, 07:19:56 AM »

I spent several hours last night searching with both functions and reading the threads, but the threads never really seemed to come to any resolution. It seems to me that this is a fairly wide departure from the direction the folks around here and Piggot have taken in that they are basically saying they will take the efficiency losses and overbuild the blades in the name of building a redundant off the shelf machine that produces what a good sized home needs. For those that dont live here those wind numbers may sound extreme, but on my place I literally do not have a tree within 1/2 mile. I think with this machine you could even look at re carving new blades to increase swept area down the line if you needed more low end torgue. Comparing the axial flux designs to this to me is sort of like comparing a sports car to a silverado. The sports car is lots more fun to drive and gets better mileage, but my 1985 Chevy silverado has parts available from the junkyard and is good for 300000 miles at 8 miles to the gallon if I change the oil.

I need to get a holf of the guy from Uath and visit with him, or if anyone else has bought the plans or built them. A couple weeks ago I posted a question on the newbies regarding using generator heads, and to me this solidifies a lot of the thoughts I was having at that time.

I also need to get hold of my guy at the power supplier here. He was out to visit me the other day, but I did not ask the right questions now. I can't believe that it is as easy to couple and synchronize? the energy from this to match up with the grid system. But if you cant, then it looks like this design would be worse than having nothing.

Setting aside the positives of the axial flow, you electrical engineers, is this power possibly of the quality they are saying???

Tom

neilho · « **Reply #9 on:** February 22, 2007, 07:34:11 AM »

"Setting aside the positives of the axial flow, you electrical engineers, is this power possibly of the quality they are saying???"

I'm not an electrical engineer, just a wind mechanic with a fair amount of experience with small induction gridtie machines. The quality of the power is exactly what the utility supplies.

These are induction grid tie machines- pretty simple in concept, but as usual, the devil is in the details.

The Prairie machines haven't been around long enough to work out any possible structural problems. For instance, they use a welded rotor plate that looks like fatigue failure waiting to happen and have no overspeed control on the rotor. It seems like a small thing, but for power outages, gearbox, generator and control failures, overspeed control is critical. Yeah, most of the time there won't be a problem, but it only takes one shutdown failure in a high wind to make a pile of junk out of an almost perfectly good wind turbine.

$.026/kWh is a tough rate to try to break even. Wind farm operators don't even try to make money at that rate, and they have a tremendous economy of scale advantage over small machines.

Your RECs attitude towards interties can be a big factor, too. South Dakota doesn't have a net metering law or interconnection standards so the utility can, under federal law, legally demand expensive under/over frequency and voltage intertie and power outage protection, can charge to install separate meters for use and production and charge a monthly fee for their use! Maybe it's not a problem, but check first. A hostile utility is a killer for small wind interties. Google "South Dakota""net metering" for more info.

If you do decide to go ahead with it, there are similar used Enertech machines out there - 4kW and 5kW- that would be a lot cheaper and with a pretty good structural history.

The big plus in your situation is that you've got a great wind site and you should be able to get good production from your turbine. (I'm envious!)

Neil

finnsawyer · « **Reply #10 on:** February 22, 2007, 08:23:09 AM »

It gets worst than that. I saw the end of a program on future auto power plants where they talking about using compressed air. At end the announcer said that by putting a compressor on the vehicle to compress the atmospheric air using the engine power maybe they could eventually achieve perpetual motion. Good grief!

Of course, the program ignored the cost of compressing the air to start with.

ghurd · « **Reply #11 on:** February 22, 2007, 08:38:23 AM »

Thats only a Minor detail. LOL

What got me was the tire and foam recycled to bio.

They made it sound like the car would go its entire lifetime with recoved fuel from 1 junk car.

Or the last set of tires can make enough fuel to last until the new tires were worn out.

G-

finnsawyer · « **Reply #12 on:** February 22, 2007, 08:56:37 AM »

I didn't see that part. Bio doesn't like tires. They tried using used tires for artificial reefs, to no avail. Nothing wants to grow on the tires. Says it all, doesn't it?

Nando · « **Reply #13 on:** February 22, 2007, 10:43:22 AM »

Prairie turbine is good for a good wind regime.

It would be preferable to get PTO generator which can be power controlled well and produce this way the wanted power, though I do recommend that the hub of the wind mill be a Torque Pitch controlled for maximum harvesting, best and automatic RPM control even if the generator is disconnected.

Nando

scottsAI · « **Reply #14 on:** February 22, 2007, 12:50:22 PM »

Hello tljones,

Too bad SD does not have Netmetering, for small systems seems to help with the cost to spin your meter backwards at the retail rate. Allows the grid to be a nice big storage bank except in a power failure.

I am an electrical engineer. Not an RE engineer. Not a power engineer.

I work on semiconductors, I study wind generators. No expert.

I have studied in detail (read book) the Breezy 5.5 and many other designs.

To answer some of your questions.

Blade dia is around 20 feet.

The generator is a motor. If using a UL approved motor there should be no objections to connecting it to the power grid. It's already approved. Using an induction motor as a generator is one of the safest ways I can think of for a DIY system to connect to the grid, and cheapest. If the power fails, the generator quits. No islanding. Generator field excitation cost 7-15% power. Not a big hit. Considering the Axial machines 50% loss or more.

A controller is required to prevent the motor powering the blades in low winds, wasting power, can you build it?

The induction generators power should be of the same quality as the power supplied to it.

The Breezy design is like the big ones, up to a point.

The magic of the Breezy is in the blades. The blade has three zones with different TSR. High TSR for low winds, then lower TSR as the winds get higher, keeping the blades in the power zone longer than normal blades without actively changing the pitch. When the winds get high, the blades become inefficient, keeping the power produced down within the generators capability. Everything is very balanced.

If you don't build it exactly as shown your results will of course be different.

The Breezy does not have any furling system, relies on the blades doing their magic.

For a first timers grid tied system, the book offers a cook book approach that is attractive.

If the project looks within your skills, careful buying can build it for much less than $5K.

I wanted a 10kw system, did not feel good about scaling the Breezy design. I wanted the full power of the wind at all wind speeds, and control the power in very high wind speeds. Only one way to do that, I went with active pitch control and an induction generator. Have not built it yet. Have not moved to a location I can build it. Looking for property here in south east Michigan.

Email me if you would like to see the design.

Have fun,

Scott.

tljones · « **Reply #15 on:** February 22, 2007, 01:54:30 PM »

I cant make your email go.. sorry. Please drop me a line at my email, tljones@daktel.com

Tom

Goose · « **Reply #16 on:** February 22, 2007, 08:30:08 PM »

Dont' forget the liability insurance the power dicks or I mean power company will make you purchase! Just in case your 5kw goes up against the grid and wins. (they told me I might ruin my neighbors TV, then my insurance will have to pay)

I'm from SD, and I checked into this. The Insurance required will probably cost you more money then you will make.

racerII · « **Reply #17 on:** February 22, 2007, 11:22:25 PM »

Excell energy's liability requirements are $300,000 here in SE SD. I've e-mailed back and forth with their field rep., and he explained he would have to inspect it to make sure it would be safe before flying.

racerII · « **Reply #18 on:** February 22, 2007, 11:29:51 PM »

The way Excell energy's policy reads here in SE SD., is that the electricity produced can be used on site before going to the meter, so you would be getting full retail value for the produced electricity consumed. The down side is the produced electricity you don't use is sold to company at wholesale. But hey, get creative, and use it up for water heating or something with a diverter if the current starts going back to them!

tecker · « **Reply #19 on:** February 23, 2007, 05:28:59 AM »

Just make sure you have the money and some facilaties to handle the wieght for maitanace

. Work with the guys on a average wind for peek power . Money first talk later.

tecker · « **Reply #20 on:** February 23, 2007, 05:31:14 AM »

Spell smell sorry

Tritium · « **Reply #21 on:** February 28, 2007, 09:54:41 AM »

South Plains Electric that supplies most of The Rural Panhandle of Texas around Lubbock requires $1 million in liability making them unusable for small grid tie systems. They are a Touchstone Company.

Thurmond

wvuengr04 · « **Reply #22 on:** February 28, 2007, 10:49:13 AM »

Scott,

I would be very interested in seeing your design. I am an ME and have been trying to find info on the same size turbine for grid intertie.

The holy grail for me would be a direct drive wound rotor induction machine. This would save weight up the tower, reduce components, and allow for variable slip to increase the amount of power produced. Some work has been done on a very large scale with ironless stators that would make the generator of a reasonable weight. According to the paper, The airgap diameter would have to be a little less than 7 feet for a 30ft diameter rotor.

But perhaps this is a second generation concept after a more conventional design is built of similar size.

Thanks in advance for any information you can share.

Howie

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Author Topic: Prairie Turbines (Read 4294 times)