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Old 18-05-2016, 18:05   #1
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New Wind Generator Being Developed

I've never heard of this 'new' design, but it's suggesting as much as 80% return in power. If they can make a 'boat' design, it would be a significant step forward.

Silent Rooftop Wind Turbines Could Generate Half of a Household's Energy Needs
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Old 18-05-2016, 18:31   #2
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Re: New Wind Generator Being Developed

From an aerodynamic perspective it looks horribly inefficient. Lots of profile and parasitic drag.

Nowhere in the video do I see any data relating to either generating capacity or efficiency.

There are numerous art projects around that have similar aesthetics. Those large machined bearing mounts seem overly large. The supporting frame was also very inefficient in terms of aerodynamic streamlines.

Even 18th century water wells were more efficient in terms of their profile. Lot's of friction though.

Keep your wallet in your pocket for now.

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Old 18-05-2016, 18:38   #3
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Re: New Wind Generator Being Developed

I though there was not much left to be done in this field. One wants more energy, one gets BIGGER wing area, etc.

b.
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Old 18-05-2016, 18:52   #4
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Re: New Wind Generator Being Developed

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Originally Posted by barnakiel View Post
I though there was not much left to be done in this field. One wants more energy, one gets BIGGER wing area, etc.

b.
Well, that's not very optomistic

It's only a matter of time until it's worked out how to get more power from less revolutions. I hope this company has actually done so.
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Old 18-05-2016, 18:54   #5
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Re: New Wind Generator Being Developed

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Originally Posted by leftbrainstuff View Post
From an aerodynamic perspective it looks horribly inefficient. Lots of profile and parasitic drag.

Nowhere in the video do I see any data relating to either generating capacity or efficiency.

There are numerous art projects around that have similar aesthetics. Those large machined bearing mounts seem overly large. The supporting frame was also very inefficient in terms of aerodynamic streamlines.

Even 18th century water wells were more efficient in terms of their profile. Lot's of friction though.

Keep your wallet in your pocket for now.

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There's no spending to be done just yet. It's simply not available small enough for a boat. But the article suggests they are working on it. That's a positive.
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Old 18-05-2016, 19:29   #6
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Re: New Wind Generator Being Developed

https://www.technologyreview.com/s/5...than-function/

Vortex

http://www.digitaltrends.com/cool-te...mdQL4Vv8JkZsjA
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Old 18-05-2016, 20:10   #7
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Re: New Wind Generator Being Developed

I love it when home inventors think they can break the laws of physics. There is something called a Betz Law that proves the maximum amount of power than can be collected from a moving fluid is 59%. So the claim that this turbine is up to 80% efficiency is a little grandiose.

Current commercial turbines already produce between 75 and 80% of the Betz limit, so at best this is marginally better than a standard turbine.

Worse for this inventor is that the amount of power that can be collected from the wind is related to the swept area of the blades squared. So the best way to collect more power is to increase the blade size. For a fan style this is relatively easy and doesn't carry much of a weight penalty, for this style however increasing the swept are would come with a massive weight penalty that would get exponentially heavier as the size gets bigger.

At best this is no more efficient but far heavier than a traditional wind generator. At worst it's far heavier and the same efficency as a traditional system. I simply don't see the draw.
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Old 18-05-2016, 20:34   #8
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Re: New Wind Generator Being Developed

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Originally Posted by Stumble View Post
I love it when home inventors think they can break the laws of physics. There is something called a Betz Law that proves the maximum amount of power than can be collected from a moving fluid is 59%. So the claim that this turbine is up to 80% efficiency is a little grandiose.

Current commercial turbines already produce between 75 and 80% of the Betz limit, so at best this is marginally better than a standard turbine.

Worse for this inventor is that the amount of power that can be collected from the wind is related to the swept area of the blades squared. So the best way to collect more power is to increase the blade size. For a fan style this is relatively easy and doesn't carry much of a weight penalty, for this style however increasing the swept are would come with a massive weight penalty that would get exponentially heavier as the size gets bigger.

At best this is no more efficient but far heavier than a traditional wind generator. At worst it's far heavier and the same efficency as a traditional system. I simply don't see the draw.
Have you not just written something contradictory? This Betz law claims no more than 59%, but then you go on to say that 'commerncial turbines already create 75 to 80%' ?

Disclaimer: I know nought about these electric things so I'm not pretending to know, hense why I put the post up. All i know is if I treat it wrongly it bites

Edit: I've googled this Law so now I know what your talking about. But I don't think you have read the article properly. "The inventor of the turbine Marinus Mieremet says that the power output is 80 percent of the theoretical maximum energy that could be harnessed from the wind." so the inteventor is saying that it's 80's of the Betz Law thingy.

Now, you also say that conventional turbines ready 80% already, but the following is claimed on wiki.

"In practicality, most systems do not reach a performance rate of even 50% of the Betz limit, before the further limits of the air stream are ever considered, further lowering the typical rates to 7-17%. Some have claimed to approach the Betz constant and even to surpass it, but none have proven to do so".
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Old 18-05-2016, 20:50   #9
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Re: New Wind Generator Being Developed

Quote:
Originally Posted by Stumble View Post
I love it when home inventors think they can break the laws of physics. There is something called a Betz Law that proves the maximum amount of power than can be collected from a moving fluid is 59%. So the claim that this turbine is up to 80% efficiency is a little grandiose.

Current commercial turbines already produce between 75 and 80% of the Betz limit, so at best this is marginally better than a standard turbine.

Worse for this inventor is that the amount of power that can be collected from the wind is related to the swept area of the blades squared. So the best way to collect more power is to increase the blade size. For a fan style this is relatively easy and doesn't carry much of a weight penalty, for this style however increasing the swept are would come with a massive weight penalty that would get exponentially heavier as the size gets bigger.

At best this is no more efficient but far heavier than a traditional wind generator. At worst it's far heavier and the same efficency as a traditional system. I simply don't see the draw.
The site is actually claiming 80% of "theoretical maximum efficiency", not 80% efficiency.
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Old 19-05-2016, 10:49   #10
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Re: New Wind Generator Being Developed

Quote:
Originally Posted by Stumble View Post
I love it when home inventors think they can break the laws of physics. There is something called a Betz Law that proves the maximum amount of power than can be collected from a moving fluid is 59%. So the claim that this turbine is up to 80% efficiency is a little grandiose.

Current commercial turbines already produce between 75 and 80% of the Betz limit, so at best this is marginally better than a standard turbine.

Worse for this inventor is that the amount of power that can be collected from the wind is related to the swept area of the blades squared. So the best way to collect more power is to increase the blade size. For a fan style this is relatively easy and doesn't carry much of a weight penalty, for this style however increasing the swept are would come with a massive weight penalty that would get exponentially heavier as the size gets bigger.

At best this is no more efficient but far heavier than a traditional wind generator. At worst it's far heavier and the same efficency as a traditional system. I simply don't see the draw.
Yep, what HE said. I have one more thing to add, and that is that wind turbines need to accelerate (generally) to capture the incremental energy in puffs. That's one of the reasons that the SW Windpower turbines are relatively efficient; by spinning up quickly, the maintain a nearly optimum angle of attack and therefore capture the energy in higher winds (energy goes up by the cube in wind turbines as the wind increases). Therefore, if you have a heavy rotor, it seems like it would be very difficult to capture the energy in puffs.

Area and optimum angle of attack: two good things to have in turbines.

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Old 19-05-2016, 11:02   #11
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Re: New Wind Generator Being Developed

Another issue I have with this "turbine" is it does not look like it can be feathered to avoid the effects of excessive wind speed. to say nothing of all the weight aloft
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Old 19-05-2016, 11:11   #12
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Re: New Wind Generator Being Developed

Thanks for this post. I used a wind turbine at anchor in the trade winds and it generated as much as 7.5 amps for our 12 volt system. It was noisey and we reefed it when we left the boat. We hoisted it in the rigging. You needed to be cautious because it was a large wooden blade. The tethering needed to be done well. I am sold on wind generators, however.

I see the same issues as noted by others but I would classify them as skin friction and pressure drag depending on flow separation or not. I do not think efficiency is the prime concern. Safety might be the first with noise and maintenance close behind. Drag can be an issue unless a boat is anchored. I see a lot of surface area and flow separation plus the loss of moment of momentum in the spin. There is a reason we see axial flow wind turbines and propellers dominating the applications.

This is a good post.

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Old 19-05-2016, 17:36   #13
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Re: New Wind Generator Being Developed

Quote:
Originally Posted by Chuck Hawley View Post
Yep, what HE said. I have one more thing to add, and that is that wind turbines need to accelerate (generally) to capture the incremental energy in puffs. That's one of the reasons that the SW Windpower turbines are relatively efficient; by spinning up quickly, the maintain a nearly optimum angle of attack and therefore capture the energy in higher winds (energy goes up by the cube in wind turbines as the wind increases). Therefore, if you have a heavy rotor, it seems like it would be very difficult to capture the energy in puffs.

Area and optimum angle of attack: two good things to have in turbines.

Chuck Hawley
Alerion Express 38 Yawl "Surprise"
Theoretically, energy goes you by the square (^2) as winds increase over the operating ranges. (double the wind, four times the Watts). In practice it is more like ^1.7 or ^1.8.
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Old 20-05-2016, 07:22   #14
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Re: New Wind Generator Being Developed

Quote: "It's only a matter of time until it's worked out how to get more power from less revolutions. I hope this company has actually done so."

You are kidding, I'm sure :-)

You canna get more energy out of the wind than is contained in the "tube" of air that passes through your device. So far, the best of the best have been maxed out at something like 48% of that energy. That's attained by the huge "wind turbines" you see on "wind farms".

To extract more energy from a given wind, you have to increase the frontal area of the extractor. Rather like reefing in reverse :-)

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Old 20-05-2016, 16:00   #15
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Re: New Wind Generator Being Developed

Having a business interest in the small wind industry, I am even more appalled at untruthful and misleading advertising. Maybe they mean their machine can achieve 80% of the Betz limit, which means the blades capture 80% of 59%; doing the math, that means it captures slightly less than 48%, which is impressive, if true. Many people won't realize this, and will think it captures 80%. At the risk of getting too deep into the weeds, the energy captured by the blades then needs to be converted into electricity, and there are more losses there. If you are thinking of wind for your boat, you may want to go to NREL's web site, where you can learn some basics about wind power.
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