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Sandia Labs investigates new offshore wind turbine designs

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August 1, 2012

When it comes to large-scale applications, vertical axis wind turbines are traditionally c...

When it comes to large-scale applications, vertical axis wind turbines are traditionally considered less economically viable than horizontal axis wind turbines

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Albuquerque-based Sandia National Laboratories is conducting comprehensive research into the viability of vertical axis wind turbines (VAWTs) for offshore use. The design, previously considered impractical for large-scale applications, has the potential to transform offshore wind technology, making it a more economically viable energy source.

The research is being conducted under a 2011 Department of Energy (DOE) solicitation for advanced rotor technologies for wind power generation in the United States. The US$4.1 million research project began in January of this year and will continue for five years. The first stage will last two years, during which time, several concept designs will be created and run through modern modelling software. The most workable of these will then be selected and undergo a three-year construction period before completing a rigorous test regime, measuring its effectiveness against the most extreme conditions that turbines must endure in an offshore environment.

In the 1970s and 80s, VAWTs were actively developed as wind power generators, exhibiting simpler designs than their horizontal-axis cousins and proving generally more reliable. However, once wind turbines began to be scaled up in size, the lower cost of rotors for horizontal axis wind turbines (HAWTs) seemingly relegated VAWTs to the history books.

The project will reassess the economic implications of large-scale VAWTs, with the goal of making them a cost effective and viable method for generating energy from offshore breezes. In doing so, it aims to address the national energy challenge of increasing the use of low-carbon generation.

The costs associated with offshore wind power differs significantly from land-based turbines. Offshore turbines are significantly less accessible, making the initial installation and ongoing operational challenges more expensive. VAWTs offer a number of significant advantages that make maintenance easier, and may well reduce the economic footprint of offshore wind energy. They exhibit reduced machine complexity and better scalability to very large sizes, while a lower center of gravity affords them improved stability when afloat. Additionally, the drivetrain is closer to the surface on a VAWT, making maintenance easier and less time-consuming.

VAWT turbines offer a number of significant advantages over the more common HAWT design
VAWT turbines offer a number of significant advantages over the more common HAWT design

However, there are numerous and significant challenges that must be overcome before VAWTs can be used for large-scale offshore power generation. The first of these is the problem involved in manufacturing the complex, curved blades. Iowa State University and TPI Composites will address this issue, exploring new techniques to allow for the production of geometrically complex VAWT blade shapes on an unprecedented scale, without incurring unacceptable costs.

The second problem that must be addressed is the issue surrounding the cyclic loading on the drivetrain. VAWTs have two “pulses” of torque and power for each blade, determined by its upwind or downwind position. This “torque ripple” produces unsteady loading, leading to drivetrain fatigue. The project will have to have to evaluate new rotor designs in order to smooth out the amplitude of the torque oscillations, while once again keeping an eye on the cost.

The project is currently in the prototype stage, with a number of project partners working on the various problems. Josh Paquette, one of Sandia's two principle investigators on the project, explained the overriding impetus of the project, stating that “Ultimately, it's all about the cost of energy. All these decisions need to lead to a design that's efficient and economically viable”.

Source: Sandia National Laboratories

About the Author
Chris Wood Chris specializes in mobile technology for Gizmag, but also likes to dabble in the latest gaming gadgets. He has a degree in Politics and Ancient History from the University of Exeter, and lives in Gloucestershire, UK. In his spare time you might find him playing music, following a variety of sports or binge watching Game of Thrones.   All articles by Chris Wood
19 Comments

Oh boy, here we go again! Antiquated designs being tried out.

It took an awful long time to realize that the 3 bladed fans were horribly inefficient and here we go again with another flapdoodle.

Seems a shame that the venerable Sandia Laboratories have to waste more money.

What the world needs is a valid, legitimate wind energy testing facility without a supercharging wind tunnel to precipitate lies on performance. The 1946 3 bladed flying design really has been a horrible tragedy, unconcealing exceedingly flawed engineering and now it's a horror show telling people that those designs really are not the hope for humanity. They are perfect examples of bum engineering foisted upon the public by a corrupt chain of engineers and politicians.

A fine development facility perhaps as some fine engineering school could sort this all out and we would know which design, if any, could out perform Bill Allison's 59% efficient 10 bladed fans.

This arena has been nothing but a sham, and costly one at that.

Bill Dickens

Island Architect
2nd August, 2012 @ 10:04 am PDT

The major problem not solved is unlike with the coventional wind turbine the blades are not 50 meters or so above wave height. Though this is going to be compensated for in the design structure, in rough seas - and the best windy days are rough - this turbine is going to literally plough the ocean waves (Wave height 2.5 - 4m), so we will not be getting the full benefit of the power generated and torque will be impressively different across the structure when it enters the sea.

Is there actually any reason for not raising it to an acceptable height above the waves ?

L1ma
2nd August, 2012 @ 10:40 am PDT

Island Architect,

Again with the Bill Allison mention? You bring this up every single time and never with a shred of proof that his design ever worked. His patents are all expired and any decent engineer would be able to easily reverse engineer his design if it was anywhere near efficient as you keep claiming. Why do you think every single company in the world ignores it? A massive conspiracy against efficiency?

Every time you embark on this personal crusade, it makes readers think you're like those people who claim the oil companies bought and buried the 100mpg carburetor. Why don't you build a new Allison turbine and show everyone that it works as well as you claim? The wind turbine manufacturers would be beating down your door to make you a multimillionaire if you could do that.

Gadgeteer
2nd August, 2012 @ 08:59 pm PDT

I don't think they will get the tower to stay vertical in heavy winds with that hull design. I would put more volume just below the surface with significant weight at the bottom of a long shaft. There is also the difficulty of holding the base stationary against the torque of the rotor. If you have a steady current you could just use a stabilizing fin, there is also gyroscopic stabilization but passive methods are usually more reliable.

......................................................................................................

re; Island Architect

Prove your ridiculous claims by getting rich selling electricity; the rest of us will stick with designs that have been engineered using models that the experiments on have been repeatable. You are claiming that the entire wind energy industry is made up of idiots and it has achieved a nonsense that is at best boring.

.......................................................................................................

re; L1ma

Where did you get your numbers for the height of the bottom VAWT turbine blades, the drawing of questionable scale?

Slowburn
2nd August, 2012 @ 10:20 pm PDT

Finding any information about Bill Allison is very difficult. There is one article in popular science back in 1980. Thats it. Someone claiming to be his son mentioned that he died in1999 aged 91. Other than that, Nothing.

Gadgeteer's challenge to put up or shut up is hereby seconded.

nutcase
2nd August, 2012 @ 10:50 pm PDT

The layperson who devises a way to harvest energy from both wave action and wind (possibly balancing the two) in the same device will be the one who lays claim to "best design". I'm not talking about two separate systems in one device but one integrated system which uses the two forms of energy to achieve superior efficiency and, one supposes, increased reliability.

Mirmillion
2nd August, 2012 @ 11:19 pm PDT

Another way of dealing with the torque would be to have counter rotating rotors.

re; Mirmillion

Putting wave harvesting devices on the tower is one thing but you're trying to make a combination of things that work entirely differently. I am not saying it can't be done but it would be more trouble prone and would have to deal with the fact that while the wind causes waves on the ocean the waves travel thousands of miles from where they were formed and have no correlation with the wind over most of that distance.

Slowburn
3rd August, 2012 @ 04:56 am PDT

Re Slowburn;

Wind Power Guide - Richard Jemmett

Wind Power Woofenden Ian

Try Googling.

As to the VAWT if you know better please print, and explain the concept of top hamper in relation to tall masts with sails and shallow bottomed vessels. Anchoring does not mean stability either in the horizontal axis or especially in the vertical - you looked at the diagram, it should be obvious.

You are also being offensive to other posters again which is not necessary.

L1ma
3rd August, 2012 @ 05:03 am PDT

re; L1ma

Why did you bring up that anchoring does not

provide stability I never suggested it did, and I did suggest ways to make the hull more stable. I will also suggest that if you set up two rotors that spin in opposite directions could solve the torque load problems, and provide gyroscopic stabilization.

Island Architect calls all modern windmill projects outdated at best claiming that his hero has a better design despite the fact that nobody has been able to reproduce Bill Allison efficiency using his designs. So either every wind energy company is not profit motivated or Bill Allison's work is flawed. And Island Architect has been informed of this repeatedly.

Slowburn
3rd August, 2012 @ 06:03 pm PDT

re Slowburn;

All the features you mention were left out of the design to reduce costs, which would have given it the advantage of a smaller structure with ground level accessable generators. Would work on a hilltop, not at sea. But if contraprops are your solution to the torque problem, replacing our conventional turbines doubles the power output - and easily doubling the costs.

Island Hero wrong ? the concept is right, the US entire farming community depends upon wind pumps using a fan blade turbine. Set at height with the usual 11 ft per second wind speed these type of wind pumps have quietly watered farmland for over a century.

L1ma
4th August, 2012 @ 03:52 am PDT

Slowburn,

It would actually be advantageous for these turbines to heel in heavy winds. With no brakes and no feathering capability for the blades, the turbine tilting over could provide some protection from overspeed conditions, much like old farm turbines - also with fixed geometry blades - would be yawed out of the wind to protect them.

If Island Architect is to be believed, China must be in on the conspiracy to generate less electricity from wind. They like to steal American intellectual property whenever possible, yet not even Chinese companies are using anything like Allison's design. Obviously, nobody wants a competitive advantage.

Gadgeteer
4th August, 2012 @ 10:01 pm PDT

re; L1ma

They are trying to reduce the cost per kilowatt so doubling the output at the instillation at the price of doubling the cost of the instillation does not change the cost per kilowatt.

You could put one turbine inside the other, or have the shaft from the upper turbine come down outside structural mast and have the generator at the base.

Wind pumps are used to provide water for livestock, perhaps a kitchen garden, and even to fill the water tower for household consumption but not for general irrigation; they do not produce a large enough flow nor is the flow continuously enough for the job.

re; Gadgeteer

It is possible to engineer the shape of the blades so that they passively loose efficiency as the wind speed increases, or put active spoilers on the blades that are deployed to reduce the efficiency of the blades. I prefer the slightly higher efficiency of the active system but understand the advantages of the passive design as well.

Great point about the PRC.

Slowburn
5th August, 2012 @ 08:33 pm PDT

The Australian agricultural landscape is littered with the remains of blown-out "windmills", usually sitting alongside the "sun-mill" that replaced them in the nineties.

I've seen a few attempts at VAWT (including some of my own) and the most successful ones use two 44gal drums. I found the trickiest part was a finding a decent bearing for the whole shebang to sit on.

I'm having fun (and some success) with "microturbines" made from duct-tape, pushbike wheels and stepper motors....

nutcase
5th August, 2012 @ 10:43 pm PDT

Re Slowburn;

VAWT - the advantage to VAWT is not cost but durability

http://www.thecollaboratoryonline.org/w/images/Group_Orientation-Small_Scale_Wind_Turbines.pdf

http://www.helixwind.com/en/newsDetail.php?nid=78

Reducing the cost of installation removes the durability advantages inherent in the design. The design group in this article tried to cut costs, The problem of increasing complexity increases cost, the HAWT only has to have its costs dropped for a 2 for 1 build cost basis for the VAWT, it has over a 30 year lead in mass production and those bought in the current GW campaign have lots of service life left. The key word here is mass production, which is why we went the HAWT route. You can argue the toss as to which design is best or not, but the world went HAWT.

L1ma
5th August, 2012 @ 10:59 pm PDT

I forgot to mention that windmills that pump water are operating a low speed mechanism and at a low RPM used for operating a piston pump a high number of blades work well but at a high RPM such as necessary for generating electricity The three blade design captures just as much energy from the wind. The book on wind power that I read that mentioned Bill Allison claimed that his claims of efficiency were at generating electricity. Different jobs require different designs, go figure.

..............................................................................................

re; L1ma

My antiquated computer does not support pdf files but surely you have noticed that there are inherent differences between small scale and large scale operations.

The additional complication of the two turbine on one post I suggest as a solution to the complication of keeping a floating base from spinning under the torque load is a few bearing and a few sliding electrical conduction joints and with the right design you can avoid the sliding electrical conduction joints.

Of course you could counter the torque load with a stabilizer fin in the wind or by not floating the tower but planting it firmly into the seabed.

Slowburn
6th August, 2012 @ 03:33 am PDT

Re Slowburn;

It is as nutcase stated with the piston pump design that you would have to find your "windmill" in a field somewhere after a storm, the reason why they still persist is because they are cheap to repair. This is not because the design is inefficient but too efficient and without any active means of protecting your turbine from the event. HAWT are more complex and a step up because they were developed by the aerospace industry using blades with active pitch to control rotation speed stopping the blades doing exactly the same thing - when it all goes wrong this happens

VAWT designs use their dynamo as a break, if they used HAWT technology i.e. 3 vertical rotating blades with pitch control they would be more stable at sea. The best result would be not to have the blades rotating at all, but furled into the mast in rough conditions and there is no reason why with plastic blades this cannot be done.

L1ma
7th August, 2012 @ 01:06 am PDT

Sorry; the URL did not copy correctly



Also





L1ma
7th August, 2012 @ 05:30 am PDT

re; L1ma

I have seen windmills powering pumps for stock tanks with guy-wires and self feathering systems. Hail storms that would destroy a 'sun-mill' are more common than wind storms that will destroy such a windmill and such winds are likely to destroy the 'sun-mill' as well. Besides the windmill is more Picturesque and the pump is easier to hand operate.

Nice videos but why in a discussion of VAWTs did you bring in HAWT fail videos?

There is not video of it but during a wind storm both lugs on the windward side of a producing turbine failed virtually simultaneously resulting it the turbine falling directly backward off the tower and do to the rapidly turning undamaged blades it helicoptered about a kilometer down the valley. But just imagine what happens when you get a high power vertical wind-shear event centered on a VAWT or maybe a tornado.

I've mentioned from time to time that I am not a real fan of wind or solar power but that is no reason to not try to nudge it into working.

Slowburn
7th August, 2012 @ 10:48 am PDT

@ slowburn

At this time there are no videos of VAWT turbines failing, I can remember in the 1970's a massive campaign against the design with several films of multi blade VAWT turbines exploding, but they dont exist today. If there is a message to get across is that if a VAWT turbine is built and it fails the guarenteed result is front page pictures and a not so subtle industry whitewash against VAWT.

L1ma
7th August, 2012 @ 09:44 pm PDT
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