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Wind power generation

08/22/2008 5:41 PM

Does it make sense to use drive shafts to put the wind generator at the base of the propeller holding pole, making easy access to the generator and allowing the pole to be lighter? Does it make sense to have multiple wind propellers pump water to a tank, and then that tank supply water to one big generator? Huge wind farms are being proposed, and their size may make design changes necessary.

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#1

Re: Wind power generation

08/22/2008 5:48 PM

One word:

Losses

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#15
In reply to #1

Re: Wind power generation

08/24/2008 11:18 AM

one word Beats two words:

Do math.

milo

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#2

Re: Wind power generation

08/22/2008 6:00 PM

What you're proposing with the generator being at the base would actually cause more maintenance and cost without any increased output. The generator would be easier to access, but you would have to service the drive shafts as well which would be extra cost to factor in. Adding to that, the drive shaft for such a distance would possibly make the whole device more expensive even with having a lighter tower.

I'm not clear on what you may be getting at with the whole water to tank to generator, but if you are proposing using windmills to pump water through a hydroelectric generator, it just seems like a wasted step. If you have enough wind to turn the propellers then just make electricity that way, but I may not be understanding what you are trying to explain. Please provide more details.

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#3
In reply to #2

Re: Wind power generation

08/22/2008 6:57 PM

Hundreds of wind driven pumps would fill the tank or reservoir, and the water would turn just one generator. There might be savings in needing only one generator instead of hundreds.

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#5
In reply to #3

Re: Wind power generation

08/22/2008 8:08 PM

Ahhhh now I understand. I think there are possibilities with this idea, but let me throw this in to see what you think. What if instead of water from for example a stream having it be a closed loop system, still goes through one tank and generator but then empties into a tank that is pumped from. Not all places have ample water supply and this would remove drought scenarios, it wouldn't even have to be water, it could be a glycol solution or anything that would pump through well.

Thoughts?

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#7
In reply to #5

Re: Wind power generation

08/22/2008 9:52 PM

Your right. A closed system say in west Texas would make sense. The amount of liquid would be large, and the characteristics of water are well understood, so water would probably be used for the first such system.

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#19
In reply to #2

Re: Wind power generation

08/24/2008 4:08 PM

I think that he is thinking of using the potential energy of the water in the elevathed tank as an energy storage system instead of the batteries.

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#4

Re: Wind power generation

08/22/2008 7:27 PM

I think it's got some merit in this application:

One of the difficulties with wind power is matching supply to demand, especially when both vary greatly. Your idea would permit the water tank to be used much like a huge filter capacitor. So, if you had a farm on top of Iron Mountain and wanted to still be able to watch professional wrestling on nights when there was no wind, this would let you do it.

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#6

Re: Wind power generation

08/22/2008 9:33 PM

Oddly enough, your reference to linking wind generation to hydro is being seriously looked at right now.

The utility for which I work has, for several years, been investigating the feasibility of a pumped-storage facility to complement our existing hydro project. Recently, this has become very attractive due to a large expansion of our existing wind farm (with plans for further expansion over the next few years). The idea is that during our peak demand (day) when there is little or no wind, we let gravity do the work and run the pumped-storage facility as a traditional hydro plant. Then during our peak wind when demand is lower (night), we use the energy from wind generation to pump the water back to an upper reservoir.

During the recent federal relicensing of our hydro project, authorization was given to construct a large pumped-storage facility. It will probably be several years before it actually happens, but the plan is there.

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#14
In reply to #6

Re: Wind power generation

08/24/2008 10:43 AM

Mark684 is right. but the expenses in building the reservoir and associate installations may overcom the benefits.

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#8

Re: Wind power generation

08/23/2008 11:51 PM

How about this one.

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#24
In reply to #8

Re: Wind power generation

08/25/2008 7:40 PM

Can't quite make out what it is. Do you have a link to a larger picture or some sort of operating description?

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#25
In reply to #24

Re: Wind power generation

08/26/2008 8:59 AM

Its an old english wind powered grist mill.

milo

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#9

Re: Wind power generation

08/24/2008 1:05 AM

I have some ideas to bring the electrical machine down to the base of the tower as you suggest. But I don't think it would make the tower lighter. You see the electrical machine is not the most significant load on the tower; it is the gearbox which boosts the turbine RPM of some 30, to 1500 at which the electric generator works which is heavier. Then there is the wind load on the turbine and its enormous torque. Yet if the mechanical power can be delivered at the base of the tower ther are advantages. For example, you could have a slower (larger) electric generator and then you don't need to step up the RPM so much. The electrical connection from the generator to a fixed point is no longer an issue. And there is the ease of maintenance as you have pointed out. I strongly feel that there is a case for our idea of putting all the electricals at ground level. I have tried to push this cause, but with no success so far. And I am too poor to fund even a low power proto. I would be most grateful if some of you out there can put me on to one of the wind power machine manufacturers who will give me a hearing. As for the hydraulics; I am not with you. Hydraulic transmissions are not efficient in general as I understand.

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#10

Re: Wind power generation

08/24/2008 2:22 AM

No. No.

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#11

Re: Wind power generation

08/24/2008 9:23 AM

I am really so interested about this field ; but to solve this problem you have to find power transmitted between gear and generator Or between the drive shaft and gear box

i think that belt can be the best choice you have to do this

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#12

Re: Wind power generation

08/24/2008 9:25 AM

There are some applications of ocean energy conversion systems utilizing hydraulic systems; the turbines operate hydraulic pumps which charge accumulators; the accumulators feed hydraulic motors which drive the alternators. In this case, efficiency is less critical than extending the power availablility to peak demand hours...

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#13

Re: Wind power generation

08/24/2008 10:29 AM

Mechanical losses could be tragic for this system and balance for a shaft of the length would be difficult. Also, as the wind speed would fluctuate it could set up harmonic vibrations. If, however, the generator (alternator) were at the top of the support but in the vertical, then the mechanical losses and balance problems would be minimised while yet allowing for only a climb for maintenance.

I would think that I better solution for placing the generator (alternator) at the base would be by using a hydraulic system with a pressure reservoir to transmit the energy from the wind turbine to the generator (alternator). This would then allow for a smoother transfer of power as the wind fluctuates and also reduce an harmonic vibrations.

Finally, keep in mind that the current systems have a lot of expedience in operating and maintaining power generation via wind turbines. Thus, anything we might consider can be like re-inventing the wheel. I would want to look at all of the schemes existing before attempting to design my own system. Perhaps the best has already been designed.

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#16

Re: Wind power generation

08/24/2008 11:45 AM

Here are a few mare design options worth looking at while you're trading off maintainability.

USE EXISTING MATERIALS (street light poles?)

EASY TRANSPORT IN SMALL VEHICLE (max length 6m)

EASY DEPLOYMENT

EASY MAINTAINABILITY

These could probably be met using ONE MAN. A couple ropes would be useful for hoisting turbine. Renderings show 150mm diam poles with 6m to swivel, 2m length turbine blades. Base plinth of concrete, resulting in sturdy 11m tower.

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#18
In reply to #16

Re: Wind power generation

08/24/2008 1:34 PM

Hey I like it... no climbing, more SAFETY, real quick

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#17

Re: Wind power generation

08/24/2008 12:33 PM

The old Fairbanks-Morse windmills that they used in farms in the '30s to pump water had a gearbox and crankshaft on top. The crank was connected to a pump at ground level with a long wooden rod. It worked very well, and the only maintenance atop the tower was to add oil to the gearbox.

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#20

Re: Wind power generation

08/24/2008 7:46 PM

Others have3 mentioned the losses associated with any drive train, I think the theory behind the system at this link http://www.artemisip.com/index.htm is what you are after. The advantage with hydraulic drive is the ability to produce a constant velocity drive to the alternator from varying and unpredictable turbine inputs. This means your output can be set at 50 Hz or whatever your normal house frequency is and also maintain a set Voltage.

Be aware you will need to use a light weight Hydraulic fluid to avoid gravitational losses and put an accumulator in the line for 'no wind' periods

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#21

Re: Wind power generation

08/24/2008 11:00 PM

Its not just engineering with alternative energy. A lot is dollars and sense. If the water storage system allowed generation during peak demand periods as opposed to any time the wind blows hard enough then the dollar / Kw differential would go a long way toward paying off the system development costs. Peak demand production sells for 2-5 times the rate of non-peak production.

Also, a centrifugal pump is simple and highly efficient. Which would greatly simplify the tower top and prop mechanisms.

However, piping is not very efficient. So, small towers feeding a large pipe would be good for simple pumps but would be very bad for a long uphill run so pooling and staged pumping would be needed which would cause BIG losses, or, a hybrid pump that is both positive displacement and centrifugal. There are some existing designs of this type that might suit the application. Otherwise the horsepower to discharge feet of head limitation for centrifugal pumps would make this approach unworkable.

http://www.patentstorm.us/patents/6824369/description.html

This link is for one type of hybrid pump of the type I am talking about. There is another from a engineer in Louisiana that seemed to me to have some merit but none of these hybrid pumps are in current production to my knowledge so it is a bit of a gamble as to performance.

The generator's or alternators are not the high maintenance component of current systems so getting them off the tower is no advantage. The gears and bearings of the current variable pitch systems are problematic which is why the pumping approach which is a possible alternative to these components may have merit and dual water use applications such as pumped storage with secondary irrigation water delivery would give a proposed system two income streams instead of one, and yes, the pun was intended.... My bad.

Sincerely,

Mr. Gee

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#22

Re: Wind power generation

08/25/2008 9:17 AM

Hi Frank,

I like your idea of the verticle wind generator and to use hydro to provide consistency in power requirements when it is needed. Here are 3 links to sites that use vertical generation and one that is quite different, although I suspect commercial application and noise may be an issue. The last site seems to have an answer to both of these issues.

http://www.guardian.co.uk/technology/2008/jan/29/wind.energy.aerogenerator

www.metacafe.com/watch/1097201/windbelt_electrical_wind_powered_generator_demo/

http://www.quietrevolution.co.uk/

Rol-N

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#23

Re: Wind power generation

08/25/2008 4:42 PM

Frank12

Your question sure resulted in lots of fringe science falling out of the woodwork!

Here's an attempt to answer your questions with some seriousness. Lightening the mass at the top of the pole will not allow one to make the pole lighter, because the forces generated by the wind on the turbine blades pushing on the pole are far larger than the weight of the generator and equipment. Therefore most of the design of the pole is related to resisting the overturning forces of the turbine blades.

Another note: the extra gearbox(es) and driveshafts necessary to bring the mechanical power to the base of the windmill simply represent added cost and efficency loss to the owner of the windmill, so they will want to build the windmill with as high an efficiency as possible. (higher efficiency= more kilowatts to sell.) This means to minimize the driveline length and complexity as much as possible. Nobody cares about the poor schmuck who has to walk up a gazillion stairs to the top only to realize he forgot his left-handed monkey wrench back at the service truck at the bottom!

Regarding water storage, as others have mentioned, is under investigation. However, this step involves a large efficiency loss--water pumps of any sort peak out at 90% efficiency or so ( give or take a few percent) and water turbine generators are in the same range. Other losses pick away at the efficiency--pipe flow losses, electricity generation at the hydro turbine losses, etc., etc. So the best efficiency you could expect from pumping water would be about 75% or so, and this is on the high end. To state it another way, if my wind generator generates 1 hp, I would be able to recover only about .75 hp of saleable electrical power after I put it through pumped storage.

Others knowlegeable with pumped storage may be able to tell you what the current expected efficiency is using Best Available Current Technology. (BACT). I'll bet it is quite shockingly lower than what I have suggested!

The only way that pumped storage power generation will be done is if the power can be sold at a peak demand premium that covers all the efficiency losses. I'm guessing peak rate power pricing isn't yet high enough to pay for generation by pumped storage.

Jon.

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