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Carbon nanotube-reinforced polyurethane could make for bigger and better wind turbines

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September 1, 2011

Carbon nanotube-reinforced polyurethane could make for lighter and more durable wind turbi...

Carbon nanotube-reinforced polyurethane could make for lighter and more durable wind turbine blades (Image: Gizmag)

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In the effort to capture more energy from the wind, the blades of wind turbines have become bigger and bigger to the point where the diameter of the rotors can be over 100 m (328 ft). Although larger blades cover a larger area, they are also heavier, which means more wind is needed to turn the rotor. The ideal combination would be blades that are not only bigger, but also lighter and more durable. A researcher at Case Western Reserve University has built a prototype blade from materials that could provide just such a winning combination.

The new blade developed by Marcio Loos, a post-doctoral researcher in the Department of Macromolecular Science and Engineering, is the world's first polyurethane blade reinforced with carbon nanotubes. Using a small commercial blade as a template, Loos manufactured a 29-inch (73.6 cm) blade that is substantially lighter, more rigid and tougher than conventional blades. Rigidity is important because as a blade flexes in the wind it loses the optimal shape for catching air, so less energy is captured.

Working with colleagues at Case Western Reserve, and investigators from Bayer Material Science in Pittsburgh, and Molded Fiber Glass Co. in Ashtabula, Ohio, Loos compared the properties of the new materials with that of conventional blades manufactured using fiberglass resin.

"Results of mechanical testing for the carbon nanotube reinforced polyurethane show that this material outperforms the currently used resins for wind blades applications," said Ica Manas-Zloczower, professor of macromolecular science and engineering and associate dean in the Case School of Engineering.

A small wind turbine featuring the polyurethane carbon nanotube-reinforced wind turbine bl...

Comparing reinforcing materials, the researchers found that the carbon nanotubes are lighter per unit of volume than carbon fiber and aluminum and had five times the tensile strength of carbon fiber and more than 60 times that of aluminum.

Meanwhile, fatigue testing showed the reinforced polyurethane composite lasts about eight times longer than epoxy reinforced with fiberglass, while delamination fracture tests showed it was also about eight times tougher. The performance of the material was even better when compared against vinyl ester reinforced with fiberglass, another material used to make wind turbine blades. Fracture growth rates were also a fraction of that found for traditional epoxy and vinyl ester composites.

Loos and her team are now working to determine the optimal conditions for the dispersion of the nanotubes, the ideal distribution within the polyurethane and the ways to achieve both.

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag.   All articles by Darren Quick
13 Comments

I think Carbon Nano tubes are fine but carbon fiber is far more realistic. 5x the tensile strength but may not bee needed.

Michael Mantion
1st September, 2011 @ 05:35 am PDT

I agree, however that same argument was made years ago when Carbon Fiber was very expensive and very exotic.

Carbon Nanotubes will come into the mainstream just as Carbon Fiber has. . .

socalboomer
1st September, 2011 @ 09:04 am PDT

But what about the birds!?!? Think how many birds will be killed by bigger turbines! And the noise pollution generated by them!

Hysterics aside, should be an interesting development.

gormanwvzb
1st September, 2011 @ 09:58 am PDT

Making the blades lighter also means there will be more shock loading on the transmission from wind gusts. Lighter is not always better.

Slowburn
1st September, 2011 @ 10:33 am PDT

Stronger is always better for some apps. The cost will determine how widespread the new material becomes. Initial tests indicate this will replace Carbon Fiber. If a company had exclusive patent rights I would invest, although I hope this becomes open source. I am against patent rights in theory and in practice. In theory, a "protected idea" is based on the belief that the first to think of it "owns it". Ideas are useless without implication and it is impossible to know who thought up the idea first. We only know who got to the patent office first. It is possible and usually the case that dozens of people working on a solution to a problem separately solve the problem unilaterally. Ideas are the property of everyone who does the mental work to understand and implement them. Threatening violence against all but one thinker on an idea grants a monopoly. Monopolies are immoral and counterproductive. For example, instead of rapid spread of spin off apps by the thousands we get no new work until the patent runs out. This is anti-life, anti-thinking.

voluntaryist
1st September, 2011 @ 12:15 pm PDT

You say "the blades of wind turbines have become bigger and bigger to the point where the diameter of the rotors can be over 100 m (328 ft)." And you say the nlength but with this material how big can it get? Why are you teasing us. You rotten tech tease!!!!!!!!!!! How big? How big? How big???????

froginapot
1st September, 2011 @ 06:02 pm PDT

@ gormanwvzb. Actually, all the available evidence says that the larger blades kill *fewer* birds-because the blades move *slower*-& so birds are more easily able to evade them than the smaller, faster moving blades on older turbines. Also, modern turbines tend to be better situated to avoid areas of high bird traffic, & also are often fitted with devices to actively dissuade birds from approaching them!

Aussie_Renewable
1st September, 2011 @ 06:16 pm PDT

Re voluntaryist

The patent is the best way we have come up with to reward innovation, doing away with it gives all the advantages to the evil mega corporations which leads to far worse monopolies than giving the inventor his do.

if the inventor does not license his patent for a reasonable price others will figure out how to achieve the same results in a different manner. This is being written on a PC because apple did not license production of Macs until far to late.

Slowburn
2nd September, 2011 @ 12:14 am PDT

With Wind Turbine capacity predicted to reach 20 MW soon,it makes sense to go in for strong Blades which can with stand high winds and are durable. Carbon nanotube-reinforced polyurethane will certainly be a good choice.

Dr.A.Jagadeesh

Wind Energy Expert

Anumakonda Jagadeesh
6th September, 2011 @ 11:30 am PDT

The new windmills are exciting and in their early stages. I will list some ideas and improvements. These ideas should increase output and lower costs due to ease of maintenance.

I cannot understand why the turbines are set at the top of the tower, as just carrying a screwdriver up to do a small repair must be tiring. The design from me sets the generators on the ground with a simple drive system allowing the blades to face the wind at all times. If the windings are perhaps wound onto horse shoe type holders, perhaps we could add more then increase the output. the addition of a fluid flywheel with a lock would give us greater control so that in high winds we could add a slip, rather than close the generator down. So much can be found out with a little research. Would the addition of twin horseshoe magnates improve output?

The plans, sketches and diagrams of the windmills were not accepted.

From Gordon Mays Baird son of John Logie Baird Inventor.

Gordon Baird
11th September, 2011 @ 01:47 am PDT

Honored to post here. Five times stronger and more durable? Good for wind turbines. Great for aircraft. If a fraction of the material is needed, it further reduces the upline components in the aircraft such as engine size, landing gear weight. See Amory Lovins for how this thinking has been successfully applied to buildings, automotive, and industrial optimization. Velozzi's sportscar's using nanotube resin with carbon fiber to reduce weight by 30% and cost by 10 to 15% while increasing safety. Cost can be further reduced by reducting supporting components such as the engine, fuel tank needs, leading to smaller wing lift requirements, which reduces the weight of the fuselage again and the cycle continues until you're only talking about what it really takes to lift a pilot off the ground, which isn't much. For example, this leads to a significantly smaller, lighter, faster personal aircraft than anyone is thinking about right now.

Roger Abramson
2nd June, 2012 @ 11:06 pm PDT

Great. This means even more industrial blight on landscapes. Why must Man always aim to increase the scale of everything, include mindless population growth?

Alec Sevins
5th August, 2012 @ 05:29 pm PDT

What will it cost in comparison to other reinforcing fabrics? I'd love to be able to use more carbon fibre but its still daylight robbery for a bolt of the stuff and there tends to be more waste and offcuts because orientation of the fibres is more important.

nutcase
6th August, 2012 @ 03:37 am PDT
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