Research Project - Experts Please Reply

[countryboyPHD]

Hello Everyone,

Long time reader of the forum, great people and ideas. I am going to be doing some research with high wind turbines in the next year. I am a PHD student in engineering and have been given a grant for some research work. It is very exciting people are putting money toward research, hopefully we have reached the turning point for wind power and it will become very popular.

The research is for winds from 30 to 70 mph. I know this seems unusal but please just understand the research has to do with high storm winds. My research involves making as much energy as I can. I am going to use two main designs, one is a 3 to 4 foot horizontal axis turbine with 3-4 blades, as well as a "Panemone" design of 5' long and 3 foot high (only 1.5 foot to actual air contact). Each design has its own purpose in the research project, so again please know these variables will not change.

What I need is to design a axial flux generator that will  show me how much power I am making at certain speeds. No need to store it just yet, so I will just run the power to a dump load. I would like a 48 volt system to keep amps down. I have done alot of research but many axial flux generators do not encounter the high speeds with the HWAT. I believe the "Panemone" will be OK since it can only spin as fast as the wind pushing it (60 mph / 3 ft radius ~ 560 rpm) I think I am going to need to make two seperate generators for each due to rpm or maybe just change out the stator? Has anyone done an axial flux generator at higher rpms (maybe something with gearing?) to produce power. With the Betz equation I found at 60 mph and 30% efficiency (hoping) I can produce 6 kWh on the HWAT and maybe around 3 kWh on the VWAT.

The study also includes a study of the wind flow before and after the wind turbines. I have a full wind tunnel for testing which is why the sizes are small. I really would just like to mimic a real turbine (which is to achieve as much power as possible) for the tests.

Any information and suggestions on the study are greatly welcome. Thanks for allowing me to soak up your knowledge in these forums.

CountryboyPHD

[rossw]

With the Betz equation I found at 60 mph and 30% efficiency (hoping) I can produce 6 kWh on the HWAT and maybe around 3 kWh on the VWAT.

With a phd, I think your first project should be to learn the fundamentals of your chosen field. Your use of "kWh" in this context, twice, indicates more work required.

[countryboyPHD]

With the Betz equation I found at 60 mph and 30% efficiency (hoping) I can produce 6 kWh on the HWAT and maybe around 3 kWh on the VWAT.

With a phd, I think your first project should be to learn the fundamentals of your chosen field. Your use of "kWh" in this context, twice, indicates more work required.

This is exactly why no one wants to learn about wind technology, those who see a simple error are so brutal no one comes back for seconds. Lucky for you I'm a little hard headed. Let me correct myself, 6kW on the HWAT and 3 kW on the VWAT. Now does anyone have some real feedback?

[rossw]

This is exactly why no one wants to learn about wind technology, those who see a simple error are so brutal no one comes back for seconds. Lucky for you I'm a little hard headed. Let me correct myself, 6kW on the HWAT and 3 kW on the VWAT. Now does anyone have some real feedback?

Hmm. Perhaps I was a little harsh.

But look at it this way. You come in here with a great song and dance about how well qualified you are. "I'm a PHD blah blah", even your username just has to rub it in - was the PHD part really necessary?

You come in, first post, "I've been given a grant" - ie, you're being PAID for this. "I want you guys to give me all your experience (for free)".

Then, as if all that isn't bad enough, you use terms that suggest you don't understand the difference between such basic terms as kWh and kW.
If you've been here as long as you say, you'll know there are a LOT of people who have great difficulty grasping the difference between amp-hours, watt-hours, watts, amps, etc. If you're so learned, wouldn't it be nice to extend some professional courtesy and at least use the right terms?

Then to come back at my reply with such a sarcastic response.... well, seriously.... *I* sure won't be bothering to offer anything any time soon.
No doubt there will be some kind soul who has less of a chip on their shoulder than I, who'll throw you a bone. But I don't think you've given yourself the best introduction possible....

[ChrisOlson]

Your project sounds a little vague, actually.  What engineering discipline are you studying?  I'm a mechanical engineer, but just a regular old Bachelor's one.  The old saying where I come from is, "BS - well you know what that is.  MS = More of the Same.  PhD = Piled Higher and Deeper."

Why are you studying wind turbine dynamics at wind speeds from 13-30 m/s?  Those are only useful wind speeds for wind turbines on a couple places on earth - both of them near the poles.  It would help to understand the reasoning here.

If you're not storing power (batteries) and only running into a "dump load" (resistive?) why are you limiting yourself to 48 volts?  That just doesn't make sense.  How do you plan on regulating it?  There's a thing called "Ohm's Law" and it's pretty easy for any freshman engineer to figure that out.  So, again, what's the reasoning behind this?

Yes, I have built lots of geared axials.  That's all I do build.  But you're not going to drive one with a one meter rotor.  A one meter rotor running at wind speeds over 13 m/s at TSR 7 will be turning over 2,000 rpm right at the beginning of the test.  Again, I fail to see the logic.

I think we would need to see your wind tunnel facility (and arrange to let me use it for helping you out), and the complete dataset of test parameters to make any reasonable recommendations because getting an axial to hang together (not to mention the prop) at speeds over 2,000 rpm would even tax my engineering skills.
--
Chris

[countryboyPHD]

Maybe I over estimated this forum. I never said anything about knowing anything about turbines. You assumed I did. A PHD program is to LEARN, so of course I do not know everything.

Secondly my comments were not meant to brag, I thought individuals who have been fighting the wind turbine fight for over 10 to 15 years would be interested to see it is finally getting some funding and some coporate eyes turned toward it. Not to mention grants are for the parts and whistles, not for salary.
It just bites my butt that individuals like you, who could be helpful have to pick a fight from the start which I knew would happen from some arrogant person...

Lastly, I have found out in my short career that is much better to deal with people with experience, who have already made the mistakes I dont want to make. Experience.....has more knowledge than you could ever read or learn from some book. Instead I would like a starting point since my degree is in vibration and heat transfer FEA. Guess what...mistakes happen!! I bet you made some conversion errors when you started out, but then again I bet your not that type...To finish this whole rant off, I hope you dont offer me anything or anyone else for that matter.

I hate to judge this forum by one member, but the mods can close this.

[countryboyPHD]

Interesting Chris,

The area in question is at the poles with high wind speed. I am trying not to disclose the application due to "limits" in my grant, but the study is the polar winds being used to power snowmobiles and some portable electronic equipment. They also want to use some of the power to unthaw the turbines and equipment. Like I said I am a vibration and FEA guy so this is a new world I was sent to for my research work. And yes about the schooling, so much more of the same!

Unfortuantely I am mechanical and know little about the electrical side. What voltage would you suggest? I figured winding the coils for more voltage would decrease my power output for the larger flux gap. About Ohm's Law, I assumed the load (heating coils) would create the resistance in the line.

Haha the wind facility is on the east coast of the US which I would gladly schedule some time for some help. You seem worried about the rpms, perhaps some gearing to slow the generator. I guess you could use some kind of damper/spring system to slow the rotation of the blades but that seems like it would take away some power.

Does anyone on this site have a collaborative of axial flux results with different parameters (i.e. prop size, rpm, power, etc.)

[ChrisOlson]

Unfortuantely I am mechanical and know little about the electrical side. What voltage would you suggest? I figured winding the coils for more voltage would decrease my power output for the larger flux gap. About Ohm's Law, I assumed the load (heating coils) would create the resistance in the line.

The resistive load is just one issue.  You also have resistance in the transmission line and stator. 

Does anyone on this site have a collaborative of axial flux results with different parameters (i.e. prop size, rpm, power, etc.)

Basically, you have to select your airfoil.  There's lots of testing data done by NACA and the NREL on airfoils on wind turbines.  Once you know what airfoil you're using, then you know how much power it will make.  You don't need a wind tunnel for it to test that.  You're going to have to design your own generator for it because there is nothing here in the homebrew world designed to run over about 12 m/s.  But I will tell you this - a 6 kW (125 amp) 48V generator is going to be big.  If you run the voltage up to 600, now you're talking sense - not common sense - but it could work at only 10 amps.

But what you're going to run into is limits in aerodynamic efficiency and how high of a Cp you can actually get from that small of a rotor running at that speed.  Frankly, I think you need to look at EPU (Emergency Power Unit) specs on the Ram Air Turbines used on aircraft for emergency power.  Those are more inline with what you say you want to use this thing for than the homebrew design axials.

Now - where is this wind tunnel?  I got a brand new 3.2 meter turbine sitting in my shop and I want to test it.
--
Chris

[gizmo]

This is a interesting project. Designing a wind turbine for use in the cold high speed polar winds introduces a whole bunch of new variables. I can see an application, and a lot of questions.

You have high winds, so you could use a low TSR to keep the RPM down without loosing power, but there is a problem that hasn't been mentioned yet, icing.

Any ice buildup on a turbine is bad, especially if its running at a high RPM. Maybe a slower running turbine would be safer, but then again, a high speed turbine would tend to throw any ice off itself, at least on the outer diameter.  Some airfoils shapes may suffer icing more than others. What about heating, or blades that flex. At the end of the day, your need to stop the ice buildup is a important design consideration.

Glenn

[ChrisOlson]

I'm still trying to make some sense of this before I waste too much more time on it.

First, it was stated,
please just understand the research has to do with high storm winds. My research involves making as much energy as I can

Thermal FEA engineers aren't interested in that sort of stuff (typically).

But then,
The area in question is at the poles with high wind speed. ............but the study is the polar winds being used to power snowmobiles and some portable electronic equipment. They also want to use some of the power to unthaw the turbines and equipment.

Now, I haven't been to either of the poles, but I been dang close to the north one and all the snowmobiles I seen around Deadhorse and Prudhoe bay are gasoline.  Never seen an electric one yet.  Some of the Snow Cats were diesel.  but I can't think of, nor have ever seen, any sort of snowmobile that needs a wind turbine to power it.

Joe and Marcellus Jacobs built a wind turbine for the Richard Evelyn Byrd expedition to the South Pole in the 1930's and that turbine performed flawless down there for 32 years.  Amundson-Scott South Pole Station, McMurdo, Scott Base - all have wind power systems from Northwind HR3's to Enercon E-33's.

There is no human on earth, including Eskimo's, nuts enough to live on the Pack Ice at the North Pole.  The only way in and out of there is by air.  So it's unlikely that there would be any need for wind power at the North Pole (unless Santa Claus has gotten into RE lately).

So, really, as this has evolved, it's sounding more and more "fishy" all the time.
--
Chris

[boB]

You don't have to go to the poles to find those wind speeds. There are lots of mountain top/side communications sites
with 50 to 100+ MPH winds  (and very high average speed) that are very harsh on turbines and controllers.

We found that Clippers or always being able to load the turbine is necessary in those cases. The problems usually
start happening when the loads go away for whatever reason.

So far, every time we have added a clipper to a high speed site or even a regular site when a storm comes along, which will
eventually happen if it's a decent site at all, always makes a world of difference and makes things work so much better.

boB

[gizmo]

Australia has permanent camps at the south pole, I could see a use for winturbines there, shipping in fuel is a big expence, plus the boats can only get in for a few months of the year. Disposing of the empty drums has been a problem in th past. Solar is pretty hopeless down there.

Never heard of a electric snowmobile either, but I guess for short runs in the middle of winter they could be handy, no starting problems.

I think the alternator would have to be fully enclosed, snow at those temperatures can be like sand, very abrasive, and you wouldn't wanting it getting between the stator and magnets. Countryboy may be better off looking into a set of modifications to a commercial wind turbine instead of starting from scratch.

Glenn

[wpowokal]

Glenn Dunlight wind turbines have seen service in the antarctic, some stations today use wind turbines, so some brand is good enough.

Allan

[gizmo]

There you go Countryboy, save reinventing the wheel. See if you can get in contact with a Antartic camp and ask them about any problems they have had with their turbines and what could be inproved. Might give you a few idea's.

Glenn

[SparWeb]

Well this one got off to a shaky start... 

Since it has already been studied and optimised at the university level, I could point you to Hugh Piggott's projects.  He has 4-foot, 6, 8, and so on diameter HAWT's projects that include detailed construction manuals from blades to generator to mounting it all and runnng the wires.  For the sake of your own project you could identify the compromises that are in the Hugh Piggott design, and re-balance them in favour of a site with lots of very strong winds.  Can I sign up for a grant, too? 

Terminology that will help you with google: 
HAWT: Horizontal Axis Wind Turbine (not HWAT)
VAWT: Vertical Axis Wind Turbine (not VWAT)

Keep searching this board, too.  Several of your questions are answered (partially) on the first page of the "Wind" subject.

Oh, and it's usually bad internet etiquette to put your credentials on your alias, unless the site is directed toward professionals. 
As you can see, THIS site is run by amateurs.     No kidding, that's actually what makes this forum a good one.  Folks who do it just 'cause it's fun.
I don't put my credentials on my signature, but for you it's too late with the alias you've chosen.  Gotta live with it now I guess.


...FEA as in structures, or FEA as in fluid dynamics?

There's a lot of wind turbine aerodynamics code out there.  Sandia Labs, NREL, NWTC are all good places to do research at the theoretical/design level.

[Flux]

I see that it said " experts please reply"  That rules me out.

I can't add much that the others haven't covered. What are you trying to do?  If you want to extract the maximum power and you don't need to store the energy then do you have to be limited to a 48v fixed voltage? If you do then if you want maximum power then you are looking at some form of mppt converter. You are looking at a speed range of 2: 1 and you won't load any alternator efficiently at constant voltage when inherently it wants to run over a 2:1 speed range.

I am sure you can do it with an axial ( what sort of axial do you mean?) The air gap axial as used here with open design is not going to work in the arctic, but it will be ok in a nice cosy wind tunnel ( so perhaps you can ignore the tricky bit).

An air gap machine may not be the best approach if you want something compact and it certainly is not the best design to cool if you want to push it to extreme limits of power for unit size.

You are starting to work at the wind speeds when normal turbines shut down so you are certainly into a very tricky region.

There have been windmills developed for powering auxiliaries on aircraft so it can and has been done in wind speeds higher than you are interested in. That is probably the best place to start looking at aerofoils. For normal use I couldn't care less how well an aerofoil worked over 30mph and if it became inefficient above 30 then it would make life easier for normal use ( stall regulation works this way but I don't know how fast you can run some of the normal sections and get good results in high winds ) . You may have to adopt lower tsr as has been suggested but for alternator power out the faster the better if you don't want a monster.

I believe you can design an axial air gap alternator to work up to 60mph in a wind tunnel for a tiny prop but not to load bogged down into a constant voltage load if you want it to work below 60 mph. Whether you could make it survive real life polar conditions that is a different matter.

Are you even interested in the alternator or is it just a means of testing your prop ( dynamometer).

If you are doing the mechanical bit then why can't they find someone with a PhD in electrical machine design to do the machine design. There are papers published on axial flux alternator designs for wind power but for your application you may do better looking at servo motor designs where they are pushing the current and torque limits beyond normal wind turbine limits.

Flux

[tecker]

That's a fair sized Project . There's lots of materials for a big machine and a tall tower .I would suggest a small project with some believable goals and ramp it up when you have the skills and or help.  Your talking   wieght a good patch of land and some skilled help in a 3kw project .

[taylorp035]

Now, I haven't been to either of the poles, but I been dang close to the north one and all the snowmobiles I seen around Deadhorse and Prudhoe bay are gasoline.  Never seen an electric one yet.  Some of the Snow Cats were diesel.  but I can't think of, nor have ever seen, any sort of snowmobile that needs a wind turbine to power it.

There are electric snowmobiles..... SAE has a university challenge to make electric ones, but I haven't heard of commercial ones (I haven't researched this a ton...).  I'm not sure the batteries in them would run too well at the very low temperatures, unless you had some nice lithium cells in there.  Then you find yourself with a $30k + snowmobile....    Of course, no one said this had to be practical.   

[luv2weld]

I don't want to beat a dead horse.
But if you have been reading this forum for a long time, you have obviously missed a few important things.
Like the FAQ's. Read ALL the FAQ's. Especially this one---http://fieldlines.com/board/index.php/topic,143592.0.html

As someone else mentioned, your screen identity screams "I am impressed with myself".
Almost everyone here has a PhD in country things, even the city dwellers. We are graduates of the "Skinned Knuckle School of Hard Knocks"!!!
Forget the screen name you have now and register under some new humble name. When you are humble and ask for help, you will be
overwhelmed with the response.
Do not come in here and say you have this wonderful new idea to make millions of dollars but you want us to do the work and figure out all the
problems for you.
We like puzzles and we like helping people. We do not like being used and abused. If we are going to do the work, then we expect to get the
certificate proclaiming us to be PhD's too.
If you are a PhD candidate, you must have had some kind of education already. Using the word/term "unthaw" shows us a serious lack of
paying attention in class. The negative prefix un means NOT, as in unhappy----not happy. So unthaw (If it was a real word)  would mean
Not Thaw, as in to freeze or leave frozen.
The other thing I want to point out is there is no automatic "entitlement".

It just bites my butt that individuals like you, who could be helpful have to pick a fight from the start which I knew would happen from some arrogant person...

Arrogant is the one who has to impress everyone with how smart they are from the git go.
Just because you want help, doesn't mean you are entitled to it or will get it. Remember that you are the "outsider" here and when you offend one
of us, you just might PO all of us at the same time. If you are chastised for something that you don't think is fair or right, then you have a few
choices you can make. You can ignore it, you can apologize and pay closer attention, or you can fight. We consider ourselves as friends even though we
may never have met in person. To put it into context you should be familiar with, in school, if some new guy attacks your friend in front of a whole
crowd of your friends, what do you think is going to happen?

Ralph

[STYME JONES]

This certainly has been most interesting. most of the time on this forum people are trying to suck every drop of power out of the wind we get. here we have a situation with super high winds, everyone would like but just hate hate to live in. high towers don't seem to be necessary. i may get $#|+ for this but, sounds like some of these smaller turbines sold on the internet using alternators and carbon fiber blades may work real well for you.
 http://www.mwands.com/index.php?main_page=product_info&cPath=43_45&products_id=254   

just hook a few of these kind of units together for whatever power you want. i am not endorsing this. it just looks like a few of these units might work well there. you have a wind tunnel. try it.  STYME

[countryboyPHD]

Sorry so long to reply,

Obviously I need to give more information since it has circled into a confusing mess. The project involves me designing a vibration/damper device to cope with high wind vibration while using some fo the power made to unthaw the turbine. I understand there are many variables at play here (blade design, generator design, etc.)  for the vibration portion of this but spring constants and dampers can be adjusted using magnorheological (MR) fluid and a small electrical current (i.e. adjustable Audi suspension systems).

Someone did mention it would be very useful for the users to have wind power due to cost and convience since the long winter months bring no ships. The assumption sounds very good....thats all I say on that. Power would be used for research heating units, computers, and other equipment used for expeditions and polar research projects. The fact is beyond solar panels, that I can only assume have a hard time with the cold, there is not much for power generation . There is however alot of wind! I am to design a prototype here in the states to be dragged to the research camps and tried out. My design involves using heating loads to keep the turbine in a general operating range while also making some power. The units need to be mobile, so small blades and with no high tower. To test the vibration design, I need a small working wind turbine to simulate vibration. The heat testing will come when it is moved to the poles. The unit needs to produce enough power to heat the turbine and produce usable power.

[countryboyPHD]

Now for the details,

I do not know the electrical side of the turbine. I was told to just test out the power generation so the volts do not matter during the test. However, this is a very vague grant and I have a couple of rounds of questioning that I can ask them before starting. The voltage will need to vary with equipment since batteries are shot in the cold. I imagine they will just make the power with the turbine and use an electrical panel to break off the power requirements of their devices. Now to get away from the story.

My questions I have so far are:

I understand many people rate these generators on a volt/rpm basis. Is this a linear line that does not stop with max rpm or does it max out at a certain rpm?
If so how do I determine this max?

The lower TSR idea seems like a winner. If the blades spin slower, even in 60 mph wind, will this decrease power output? The speed of the turbine will help from the cold weather (freezing) so I do not want to slow it down too much.

Is there a way to test a coil before placing all of the coils in the stator to get a general idea of power at a certain rpm?


Basically I am in need of how to build a generator for my needs so any resources of higher rpm axial flux generators would be appreciated.

Also does anyone know of how slow the wind is after it leaves the turbine? Another idea was to place these turbines into the wind to help slow down the incoming wind to the research camps. This would just be an unexpected benefit.

[ChrisOlson]

I do not know the electrical side of the turbine

Look Professor - it appears to me that there's a lot more than just the electrical side that you don't know.  If my tax dollars are being wasted to re-invent the wheel and bolt a Monroe Sensa-Trac shock to a microturbine to dampen vibration from out out-of-balance rotor or something, I'm going to raise holy hell and fire a bunch of politicians come election time.

You better come up with a way better story than what you got, because the technology already exists, and has for years in the wind power industry, to do everything you said you're trying to accomplish (except slow the wind down for research camps with microturbines!!!).

You're talking to folks here who build turbines to power their homes.  Real turbines that work.  I suggest, before you ask even one more question that you buy and read Wind Power Workshop, written by Hugh Piggot.  You can get it here:
http://www.scoraigwind.com/books/books.htm

When you have done your homework, then come back and ask if you need some clarifications.  In the meantime, you are wasting our time with this, and some people are going to bite.  But you obviously do not even understand the basics of wind power, and we cannot teach you that on a forum.  We can only attempt to point you in the right direction.
--
Chris

[Dave B]

Well said Chris, you beat me to the punch. Sometimes I think when someone doesn't get enough of a rise out of the forum members they sign in again under a different name and start all over. It's too bad that all that negative energy isn't used for building something instead.  Dave B.

[fabricator]

IIRC  Scott brought a Jake to his base camp in Antarctica, seems like it was there for fifty years or so and still working, so yeah, they have been using wind turbines down there for around a century, the patent has run out on the invention of that wheel.

[ghurd]

A decent 3 or 5 phase, with well balanced blades, will not have much vibration.

The whole power output thing will depend on a WHOLE lot of other stuff.  MPPT for one, especially from 30 to 70MPH (cube-sq).

How much power do you need to get from a portable device?!?!?!
A 1 meter designed to start working before your design specs makes a whole lot of power at 70MPH.

'Portable' means HAWT.  The forces on a portable VAWT exclude it out of hand.  (IMHO)

Now for the details, ...

Basic questions that have been answered many times.
And that is what they are saying above.

FYI- Can't shake a stick around here without hitting a few MSs and a couple PhDs.
Not that it is related, because a PhD or MS or BS is NOT required to get the highest respect from the collective 'us', or people like me.

Of all the people I know, the smartest man I never met does not have any letters before his name, except Mr or Sir.
G-

[Photon]

Hi Countryboy,

Your tutor will no doubt have required you to have completed a literature review of your choosen area. Research papers etc.

If have obtained funding then you will have presented a powerpoint/summary of the problem to secure money and wind tunnel time.

It would be helpfull if you sent these doc,s.

I worked in a research group, my work was in relation to the built environment but my friends were researching turbine dynamics (Vestas V90 3.6MW and towers) and wind energy forecasting for power grids.
Anyway im not an expert or even close, these reserachers were and had simulation models (Matlab and ANSYS). Frankly im amazed you have funding to build something that you should be able to simulate, particularly in your chosen field.

Send us your presentation docs etc, take the university name off if your not comfortable with that.

Cheers

[ChrisOlson]

They do test wind power systems at Amundsen-Scott South Pole Station.  This is an interesting read if you like that sort of thing:
http://www.southpolestation.com/trivia/90s/turbine.html

They do a lot of fascinating research down there on all sorts of things.  But in the winter time when the temp drops to -100 degrees F, only a handful of people live there (a couple dozen) and nobody leaves the base.  Nobody.  They have had medical problems there and there is no outside help even possible during winter.

When I read stuff like this:
"The fact is beyond solar panels, that I can only assume have a hard time with the cold, there is not much for power generation"

The long time website for South Pole Station clearly shows the power plant there:
http://www.southpolestation.com/0001/01photos2.html

They got all kinds of power down there, compliments of Caterpillar.  I read someplace, I think it was on that website that is maintained by one of the "Polies" that live there, that they were trying to get like nine Northwind 100's installed down there to offset fuel usage during the six months when they are completely isolated from the outside world.  Mobile microturbines might have an application down there for summer time (when the temp is about 11 degrees F) scientific expeditions, and CHP technology makes sense for that sort of thing.  But if I'm going to help design it, I want part of that grant so I can buy some cooler toys to build stuff with (or at least get to use that wind tunnel).   
--
Chris

[finnsawyer]

I imagine I'm going to be skewered for this.  Take a look at my diary called "The Betz Limit - Again".  After you read it sit down and see if you can figure out how the old water pumper windmills worked.  Very little happens by accident and they did work, apparently quite well.  Why so many blades?  In my view the modern airplane style design really hides the basics of the process.  If this wasn't so, then designing for a particular lift at the efficiency of the Betz Limit would give that efficiency after allowing for drag and other quantifiable losses.  Not so.  Efficiency is much lower.  You can't cheat the physics (or thermodynamics).
I also have a diary concerning a certain alternator design you might like to take a look at.  It turns out one could build a dual design with say each having eight magnets with a standard three phace inboard on the rotor and my single (or three phase extension) outboard surrounding it.  There are options, but you will need to do the research.  But really, that should not be that much of a problem as you should have access to a complete shop and staff.  Good luck.

[ChrisOlson]

Mobile microturbines might have an application down there for summer time (when the temp is about 11 degrees F) scientific expeditions, and CHP technology makes sense for that sort of thing.

Hmmm.... I just read where the average wind speed down there was like 10 knots.  That's not very good for microturbines.

I think if it was me, I'd put my faith in the three 1 MW Cat prime power gensets:
http://www.southpolestation.com/0001/35161.jpg

After working on gensets for almost 20 years at Cummins I grew to have somewhat of a love affair with those things.   I think I'd just walk up to it, pet it on the valve cover, listen to it purr, and go "Nice kitty".
--
Chris

[Madscientist267]

  LOL

(sorry, wanted in on the notifications for new posts... carry on...)

Steve

[Watt]

Mobile microturbines might have an application down there for summer time (when the temp is about 11 degrees F) scientific expeditions, and CHP technology makes sense for that sort of thing.

  I think I'd just walk up to it, pet it on the valve cover, listen to it purr, and go "Nice kitty".
--
Chris

Ummm  Chirs,

That kitty you are petting is a CAT powered genset.  HaHa

[ChrisOlson]

That kitty you are petting is a CAT powered genset.  HaHa

Well, yeah.  But I like 'em all.  Especially the ones that got "MW" at the end of their power rating   
--
Chris