Why VAWT technology doesn't advance ?

[topspeed]

 


I have studied this subject now 8 years and 3 months.

This week I got to know an engineer that had made 5 kw turbine that cost 2 000 000 euros ( in 2002 ) to develope...and was filed for bankrupty in few years.

It was 3 blader helix type like recenty bankrupted X-wind in UK with 2 helix wings.



I think one reason is not to learn from the mistakes of the others.

The single blade wing and this afore mentioned system displayed 38-40 % efficiency.

The developer said the chosen 5 KW size was way too small to become a good business.

So what would be the right size ?

Other opinions ?

[clockmanFRA]

After 21years research on Wind Turbines and making ...........

"It became obvious that VAWT, Vertical axis wind turbines, were just never really going to ever deliver consistent energy year after year, and as far as we know only one design, the ‘Darrieus’, ever managed to produce power at a reasonable outlay cost. However, the metal stress on this fast-spinning design were always a big problem and this group shown in this photo from the early 1980’s, were constantly under repairs and by the mid 80’s had been decommissioned. 



Interestingly the Chinese from the 1400’s have been using a simple VAWT design on their vast open plains as water pumping and milling machines. And up until the 1960’s was still putting these simple machines into operation as the materials and design was extremely simple, with just bamboo, simple rope and Junk design sails that tacked and luffed as they rotated. I have seen one of these in operation and they are slow and have reasonable torque but were very noisy."



Yes, 'topsped', why do folk want to keep re-inventing the wheel.

 Me, i look at what is working and modify/alter the design to another use, build and then test.

[electrondady1]

advance in what way ?

[topspeed]

After 21years research on Wind Turbines and making ...........

"It became obvious that VAWT, Vertical axis wind turbines, were just never really going to ever deliver consistent energy year after year, and as far as we know only one design, the ‘Darrieus’, ever managed to produce power at a reasonable outlay cost. However, the metal stress on this fast-spinning design were always a big problem and this group shown in this photo from the early 1980’s, were constantly under repairs and by the mid 80’s had been decommissioned. 

(Attachment Link)

Interestingly the Chinese from the 1400’s have been using a simple VAWT design on their vast open plains as water pumping and milling machines. And up until the 1960’s was still putting these simple machines into operation as the materials and design was extremely simple, with just bamboo, simple rope and Junk design sails that tacked and luffed as they rotated. I have seen one of these in operation and they are slow and have reasonable torque but were very noisy."

(Attachment Link)

Yes, 'topsped', why do folk want to keep re-inventing the wheel.

 Me, i look at what is working and modify/alter the design to another use, build and then test.

Yes clockman...everything done recently isn't very cost effective..."eggbeater" was one of those ideas. The HELIX as an innovation could be another.

Seems that when you invent something new there seems to be a new problem that wasn't seen before.....and you create a new problem.

Eggbeater weight was the problem...all weight was on the ball bearing at the bottom.....also you cannot put the effective area high enough.

[topspeed]

advance in what way ?

They seem to fail for one reason or another...lotsa start ups seem to loose the client very soon after start.

Quiet simple wind turbine ought to be more popular in my opinion...and experience.

There has to be some reasons why they keep failing. Adriaan described some problems in stiff (no pitch control) systems...then again the pitch controlled seem to fail too.

Mr Kragten comment here #50: https://www.fieldlines.com/index.php/topic,150709.29.html

[MattM]

When you compare to fossil fuels, VAWT will never be cost-effective.

But as a remote water pump, they can.

[topspeed]

When you compare to fossil fuels, VAWT will never be cost-effective.

But as a remote water pump, they can.

How do you compare. Isn't it well established that they produce 38-40% effiency ( energy of the wind's energy) ?

[Crockel]

Considering that HAWTs are more efficient than VAWTs, that's where the development money is going as wind turbines get larger and more numerous.

VAWTs do have their place though. Being less visually intrusive, they have more potential for residential and private use, but with no moving parts, installers of residential renewable energy are mostly going with solar panels.

For VAWTs to be successful, they need to be as maintenance free as a solar panel and offer the efficiency of a HAWT.

[topspeed]

Considering that HAWTs are more efficient than VAWTs, that's where the development money is going as wind turbines get larger and more numerous.

VAWTs do have their place though. Being less visually intrusive, they have more potential for residential and private use, but with no moving parts, installers of residential renewable energy are mostly going with solar panels.

For VAWTs to be successful, they need to be as maintenance free as a solar panel and offer the efficiency of a HAWT.

This is possibly the right recipe.

[electrondady1]

verticals will never be as "efficient" as a HAWT  with all three blades producing power equally and the load on them relatively constant
on a Darius type the load is intermittent with some blades down wind and some up wind.
the same goes for drag mills , one blade or cup shape is pulling  the others into the wind

I started experimenting with squirrel cage designs and am pleased with the results.
 i am a bit distracted presently  but hope to get back to it soon




 

 

 

[topspeed]

X-Wind was fairly honorable attempt to make bigger busines with Helix blades: https://renewablesnow.com/news/uk-vertical-axis-wind-turbine-developer-x-wind-collapses-585789/

"Game changer": https://www.kentonline.co.uk/kent-business/county-news/x-wind-power-sandwich-administration-seven-jobs-lost-kent-county-council-1-million-pounds-loan-133125/

Aerogenerator never took off: https://www.rechargenews.com/wind/video-uk-engineers-in-10mw-turbine-race-with-aerogenerator/1-1-848869

[JW]

There was this company my uncle was involved with I think it was called Micro Turbine based in Michigan. The blades for this thing were like bull horns.

Anyway I can discuss more to the forum with no problem, if anyone wants.

JW

[topspeed]

There was this company my uncle was involved with I think it was called Micro Turbine based in Michigan. The blades for this thing were like bull horns.

Anyway I can discuss more to the forum with no problem, if anyone wants.

JW

Please do so JW !

When was this business running ?

[JW]

Well my uncle designed the "air-foils) injecting mass produce manifold? if you will. Before the founder died he racked up some awesome debt. We have an agreement with them if it can be made profitable with whats already been spent..

What im saying if they can make it work-out they will do this, its not about money.

JW

[MattM]

verticals will never be as "efficient" as a HAWT  with all three blades producing power equally and the load on them relatively constant
on a Darius type the load is intermittent with some blades down wind and some up wind.
the same goes for drag mills , one blade or cup shape is pulling  the others into the wind

I started experimenting with squirrel cage designs and am pleased with the results.
 i am a bit distracted presently  but hope to get back to it soon

Theoretically the tilted rotor concept I started a thread about should be able to derive power through the full rotation by using geometry of tacking wind used by sailors.  Long arms of the HAWT using drag from VAWT, equals low wind speed startup while using the whole rotor as a vane to keep it always in wind flow at ground level.  I'll get around to building a prototype when life slows down.  Between taxes taking a bite out of the wallet this year and the work hours, just haven't had much for free time.  The construction will be quite simple, just need to dig out my workspace and gather a few parts that I don't already have.  Its that cleaning out space in the garage and pulling tools out of storage that I am struggling most with atm.

[topspeed]

verticals will never be as "efficient" as a HAWT  with all three blades producing power equally and the load on them relatively constant
on a Darius type the load is intermittent with some blades down wind and some up wind.
the same goes for drag mills , one blade or cup shape is pulling  the others into the wind

I started experimenting with squirrel cage designs and am pleased with the results.
 i am a bit distracted presently  but hope to get back to it soon

Theoretically the tilted rotor concept I started a thread about should be able to derive power through the full rotation by using geometry of tacking wind used by sailors.  I'll get around to building a prototype when life slows down.  Between taxes taking a bite out of the wallet this year and the work hours, just haven't had much for free time.  The construction will be quite simple, just need to dig out my workspace and gather a few parts that I don't already have.  Its that cleaning out space in the garage and pulling tools out of storage that I am struggling most with atm.

Wasn't there a tilted rotor system in Idaho a while ago ?

How are they doing ?

[MattM]

Not sure, but can't help to have all that complexity.

I was aiming for a rigid arm and blades laying down so that blade twist sails downwind using high drag on one side and tacks upwind with the twist at the same angle creating low drag on the opposite side.  The ogee-ish shape naturally enhances those two goals.  Stupid simple.

[topspeed]

Not sure, but can't help to have all that complexity.

I was aiming for a rigid arm and blades laying down so that blade twist sails downwind using high drag on one side and tacks upwind with the twist at the same angle creating low drag on the opposite side.  The ogee-ish shape naturally enhances those two goals.  Stupid simple.

It would then be just another drag device.

[topspeed]

What is a bit bugging me is the fact that HAWT systems if advanced can regulate the rpms ( thus yielding constant rpms ).....will the VAWT ever be able to do that ?

Does that prevent them from becoming insdustrial scale devices ?




Also that extra piece....moment arm...does it make it too complex ?

[MattM]

Not sure, but can't help to have all that complexity.

I was aiming for a rigid arm and blades laying down so that blade twist sails downwind using high drag on one side and tacks upwind with the twist at the same angle creating low drag on the opposite side.  The ogee-ish shape naturally enhances those two goals.  Stupid simple.

It would then be just another drag device.

The difference is using tacking to aid the part of the rotation moving against the wind.  The Savonius capitulates to only being less draggy moving through that part of the rotation, and its all loss.  Sailors have been tacking into the wind for thousands of years, so the concept is proven.  The weakest angle to tack is directly into the wind, but greatly increases effectiveness at angles as small as 15⁰ off that angle.  So for only about 30⁰ of rotation you have a minimal gain, and an effective gain over the other 150⁰ of rotation.  If that gain even breaks even with its drag you gained overall compared to Savonius.  The whole range of downwind rotation has effective drag for collecting power.  Its a stupid simple concept that I'm surprised hasn't been done before.

Did I mention that because the strongest part of the blade - its width - absorbs the forces, the build doesn't require the same heavy duty construction of HAWTs?  The Savonius requires a beefy shaft and bracing of that shaft.  Because it can be built lighter, and doesn't require that long and durable shaft, won't need all the extra shaft bracing of a Savonius, its the cheaper solution IMHO.

[topspeed]

Not sure, but can't help to have all that complexity.

I was aiming for a rigid arm and blades laying down so that blade twist sails downwind using high drag on one side and tacks upwind with the twist at the same angle creating low drag on the opposite side.  The ogee-ish shape naturally enhances those two goals.  Stupid simple.

It would then be just another drag device.

The difference is using tacking to aid the part of the rotation moving against the wind.  The Savonius capitulates to only being less draggy moving through that part of the rotation, and its all loss.  Sailors have been tacking into the wind for thousands of years, so the concept is proven.  The weakest angle to tack is directly into the wind, but greatly increases effectiveness at angles as small as 15⁰ off that angle.  So for only about 30⁰ of rotation you have a minimal gain, and an effective gain over the other 150⁰ of rotation.  If that gain even breaks even with its drag you gained overall compared to Savonius.  The whole range of downwind rotation has effective drag for collecting power.  Its a stupid simple concept that I'm surprised hasn't been done before.

Did I mention that because the strongest part of the blade - its width - absorbs the forces, the build doesn't require the same heavy duty construction of HAWTs?  The Savonius requires a beefy shaft and bracing of that shaft.  Because it can be built lighter, and doesn't require that long and durable shaft, won't need all the extra shaft bracing of a Savonius, its the cheaper solution IMHO.

One blade Darrieus is also beyond belief simple...so simple that I tought it had been invented long ago when I used it as an example when funders were asking why only 2 blades.

[topspeed]

advance in what way ?

Some university folks are of the opinion that Betz limit could be exceeded by 6% with VAWT.

https://iopscience.iop.org/article/10.1088/1742-6596/753/2/022056/pdf

OTOH this content does not much appreciate VAWT potential: https://www.youtube.com/watch?v=6vb18oXPli4

[SparWeb]

Betz limit isn't about the mechanism. 
It's about a volume of space where air has to go in and get out for the wind turbine to work.  If more air goes in than gets out, or vice versa, you break a law of physics.
Betz found a limit to the ability of the air to get OUT of the volume of space that it went INTO before having its kinetic energy changed.  When the kinetic energy changes, the air slows down, but still has to LEAVE if any more air is going to get IN to replace it.  So you can't slow it down too much.

[MattM]

And the crux of the matter is that volume can be any size and its constrained by the exact same limitations.  So no amount of shaping is going to suddenly unlock another 6%.  I am skeptical of the claim.

[joestue]

What about ground effects of placing the turbine on the ground?

Also why is 12% mentioned after thr 6% claim. If they calculated the betz limit for a vawt to be 11% then a 6% improvement is now 12%...

[Adriaan Kragten]

What about ground effects of placing the turbine on the ground?

Also why is 12% mentioned after thr 6% claim. If they calculated the betz limit for a vawt to be 11% then a 6% improvement is now 12%...

A HAWT can be designed such that the blade is streamed for the angle of attack alpha for which the drag lift ratio Cd/Cl is minimal and this is the case for for almost the whole blade and for any position of the blade. A Darrieus rotor has a large positive blade angle when the blade is at the front side of the rotor and a large negative blade angle when the blade is at the back side of the rotor (see figure 2 report KD 601). So a symmetrical airfoil has to be used and the average Cd/Cl ratio is therefore much higher than for a well designed HAWT. For a H-Darrieus rotor you also have the drag of the spokes which connect the blades to the hub. Airfoil drag is the most important reason for reduction of the Cp for rotors with a rather high design tip speed ratio (see chapter 4.3.3 report KD 35). So the maximum Cp of a VAWT must be considerably lower than that of a well designed HAWT.

If people have measured an unrealistic high maximum Cp for a Darrieus rotor, there is probably something wrong with measuring of the wind speed. For the calculation of the Cp, one has to use the undisturbed wind speed V which is the wind speed at least three rotor diameters in front of the rotor. If the maximum Cp has been measured for a scale model in the wind tunnel, there was probably tunnel blockage if no open wind tunnel was used. The ground effect of a low placed Darrieus rotor may have some positive effect on the expansion of the wake but the friction with the ground also results in reduction of the wind speed and this has a strong negative effect.

The derivation of the Betz limit (see chapter 4.3 report KD 35) isn't restricted to HAWT's. It is valid for any free standing device which extracts energy from the wind and for which there is a flow through the rotor. It isn't valid for a pure drag machine but it can be proven that the maximum Cp of a pure drag machine is much lower than 16/27 (see report KD 416).

[Bruce S]

What about ground effects of placing the turbine on the ground?

Also why is 12% mentioned after thr 6% claim. If they calculated the betz limit for a vawt to be 11% then a 6% improvement is now 12%...

Yeah, I found this one hard to understand too. IF they meant they gain 6% then it wouldn't be 12% but 11.66% unless they're rounding up  .

[joestue]

What about ground effects of placing the turbine on the ground?

Also why is 12% mentioned after thr 6% claim. If they calculated the betz limit for a vawt to be 11% then a 6% improvement is now 12%...

Yeah, I found this one hard to understand too. IF they meant they gain 6% then it wouldn't be 12% but 11.66% unless they're rounding up  .

as adriaan points out, once again..

the "efficiency" highly depends on the windspeed. difficult to measure without a root mean cubed calculation due to ground effects.

[topspeed]

Honestly...I have seen now 40% claim here in Finland by the Single Wing Energy company.

It has to be the best ever measure efficiency albeit the polish company ANEW claimed even 70% efficiency even for the 20 kw system some years back. There is no outside official entity that can verify this stupendously high efficiency at seemingly low wind speed.

Even if it was true...I figure the system is pretty clean and made possibly according to the findings of the Giromill VAWT 1975-1981 by the McDonnell Aircraft company.






Giromill above.

[SparWeb]

Smooth curves like that are not measurements.
They're predictions, speculations or some form of wishful thinking.
Real data is messy.  Nature doesn't cooperate with your instruments.

[electrondady1]

" When the kinetic energy changes, the air slows down, but still has to LEAVE if any more air is going to get IN to replace it.  So you can't slow it down too much."
that is the problem i discovered when working on 3 bladed drag mills. the air gets trapped and looses its energy . it has to be pushed out of the way in order for energetic air to take its place.
 i found  a squirrel cage design that did that.

[JW]

 In review  -

[electrondady1]

my camera is non functional  . this image is the closest i can come to what i am moving towards. this mill is laid down before installation .
i have built a prototype that worked nicely.