Biobased polyurethane materials and a new process from Bayer MaterialScience may help strengthen blades and decrease the weight of root rings in wind turbines while reducing volatile organic compounds (VOCs) in composites.
The traditional resin infusion process for forming large, high-strength components such as wind turbine parts uses vinyl ester, unsaturated polyester, and epoxy. These materials have limited strength and give off VOCs. Increasing blade sizes make limited strength a problem. The gravity-induced bending loads on blades increase dynamic stress, so materials that reduce blade mass while retaining blade strength are needed.
Bayer MaterialScience has developed the Baydur family of polyurethane systems for producing large polyurethane composites by vacuum infusion with increased stiffness and fatigue endurance. The composites are lighter, tougher, and stronger than their counterparts.
Composites made from a soy-based polyurethane resin can produce lighter wind turbine components, such as these root rings, that retain their strength. (Source: Bayer MaterialScience)
"Polyurethane has usually been associated with fast processing, such as reaction injection molding, not resin infusion, where gel times can be an hour or two," Dr. Usama Younes, Bayer's principal scientist, said in a press release. The Baydur resins possess low viscosity and long-gelling properties.
Compared with epoxy- and vinyl ester-based composites, the Baydur polyurethane system has a faster infusion time and superior tensile fatigue, interlaminar fracture toughness, and fatigue crack growth. "The infusion rate is about two times faster than epoxy," Younes told us in an email. "Tensile fatigue is about 10 times better than epoxy, and fracture toughness is about two times higher than epoxy. The Baydur sustainable raw material is a soy-based polyether polyol." Polyurethane also gives off fewer VOCs.
Seems like the Bayer MaterialScience technology has a lot of promise in terms of promoting wind turbine blade design. Along with materials, simulation software is also playing a huge role in perfecting wind turbine blade design and for pushing for much bigger, higher capacity blades. Click here to read about Sandia National Labs' research project effort to build a 100m blade, which in a traditional three-bladed turbine design, would take up a footprint of about two-and-a-half football fields in size. The massive blade is aimed at off-shore turbines.
Thanks Beth for weighing in about the simulation software used for wind turbine blade design. I would think that designing blades, root rings and other components of wind turbines must be quite a challenge, especially in alternative materials. It only makes sense that software is part of the design engineer's toolkit for making bigger blades possible.
Absolutely Ann, there issues around aerodynamics and airflow as well as structural integrity and reduction in weight--all key factors that can be explored and optimzed in the virtural world with FEA, CFD, and other CAE software. With simulation, designers of these wind turbine blades can test out many more design options virtually, prior to investing the money to build physical prototypes, which is a huge expense, especially with the growing size of these blades and with all the new composite materials, which are costly.
Sounds like the ability to design blades and other components using composites is probably highly dependent on that simulation ability. No doubt this is also a major contributing factor to why there's a big increase in the use of composites in so many apps, not just the fact that there are so many more versions of composite materials to choose from. Thanks for the info.
Louis, I have wondered the same thing myself. I know that there's been a lot of debate about the harm done to birds, and I have read of some efforts to ameliorate those effects.
Nice article, Ann. Turbines keep getting more efficient and more effective. Another area of research is going to create turbine blades that are optimized to gain the most of the wind. The blades are controlled to change position as the wind direction and velocity changes, the goal being to get the most efficient use of the wind at all times.
Thanks for the input. Rob. I know you've written about alternative energy sources like wind turbines, which are relatively new to me. Making them larger makes sense, but solving the weight-to-size ratio problem sounds pretty major. I bet the CAE software has made a big difference there. And I bet it's also key in figuring out how to design the blades that optimize wind, as you describe.
So far the tools to control the blades for optimum turn is still on the drawing table. Yet I can certainly see the need for it after driving by so many turbines that are sitting idle just because the wind isn't blowing in the right direction. I would imagine we'll see a ton of development in wind in the coming years.
Oh, I get it. I didn't realize you meant not only getting the most out of a particular gust of wind, but keeping them going in the first place, so they are turning whenever there's wind instead of staying idle just because there's wind but not going the right way.
Yes, the technology that's getting developed in one of those gov/industry/university projects works to grab winds that are not pointing in such a way as to spin stationary blades while at the same time optimizing the spin by adjusting the blade positions.
Funny you should raise the issue of idle turbine blades. We have one fairly large wind turbine located in my town and I have say, most of the time I drive by it, it sits idle. We live in a coastal community and the wind turbine is fairly near a pretty good size river that flows directly into the Atlantic. Needless to say, coastal winds are a big deal here. Again, despite the proximity to all this, the blades are spinning far less than I ever thought they would.
That said, I imagine the turning of the blades to adapt to wind direction has to be where it's at for future development. I would guess in addition to CAD and CAE software, intelligent sensors, embedded software, and some sort of accelerometer technology would be critical, perhaps??
Aldo, thanks for your input on the complex algorithms required to optimize the operation and performance of components such as blades. Beth, I'd also think that motion sensors and accelerometers would probably also be involved.
Yep, Beth, that makes sense to use that technology to get the blades to follow the wind. It seems a natural direction to go in developing wind turbines. In a decade or two, our current wind tools may look quite primitive. We're probably only getting 10 or 15 percent of the possible energy from our current turbines.
There's a huge wind farm near Palm Springs. It's interesting that 20+ years ago there were 10-12 distinctly different turbine designs. Nowadays about the only design in use is the 3-bladed turbine on a monopole mast. Only the size varies.
My understanding is turbines are often deliberately "parked". At low speeds the revenue from the power does not make up for the per-hour operating costs (wear and tear, maintenance, etc). I'm sure the windspeed threshold will decrease as the turbines become more reliable and/or power costs per kWh increase. (Southern California has very high electricity rates but also a surprising amount of wind power thanks to our topography).
Good points, Kenish. It will be interesting to see whether power costs increase. I would imagine conservation over the past few years must be having some impact. However, if EVs and Hybrids become plentiful, there will be more draw on the grid.
Thanks, kenish for that insight. I would guess that, with bigger blades, better optimization technology and possibly also an increase in power costs, that threshold will go up quite a bit.
Blade control is one of the areas where potential technology developments could improve the efficiency of wind turbines. Today, most turbines are using independent pitch control where each blade is independently controlled by a servo actuator. But all of the blades respond to the same command as they go through their cycle. Individual pitch blade control provides real-time feedback from blades or monitoring devices, and one approach is to embed sensors into the blades for real time load feedback. The system closes the loop at the turbine level using that feedback to significantly reduce the load variation from blade to blade. The result is an ability to handle peak gusts better and more quickly.
Al, thanks for the added details on improving turbine blade design. And you're right, the weight reduction seems to be the big deal here for composite blades, especially as they get a lot larger.
Chuck, no data of that kind was attached to the press release, but Bayer's site is pretty extensive and they may well have MDS or other such spec info located there.
Thanks, Al, for that info about independent pitch control for responding to gusts faster and handling them better. And Aldo, thanks for the input about using genetic algorithm programming techniques for increasing efficiency.
As a side note, I was watching an episode of Terra Nova last week and suddenly noticed that the wind turbines they depicted as right inside the village were insanely small and incapable of providing the power they need, even when combined with solar panels. Of course, they would have had to put large enough turbines way outside the village, where they'd presumably get destroyed by marauding dinos.
I would also expect that reducing the weight of the blades could help boost overall performance. With the emphasis on offshore installations and much larger turbines, the weight of the blades is a huge factor for design, installation and maintenance.
Hi, this is interesting for the energy industry because wind power is highly expected to become a major source or energy for many countries. Nowadays it is very attractive for investors to invest in a wind power plant when the resource is good instead of investing in a fossil fuel utility plant. I have studied new methods for optimization of turbine components like blades by using programming techniques like genetic algorithms combined with CAD/CAE software to increase efficiency of energy conversion, reduce size and weight of components and making the technology more affordable. More information about genetic algorithms used for wind blade development can be read in the following link: http://mozart.dis.ulpgc.es/Gias/Publications/mendez-greiner.pdf
At what point does the loss of mass in the blades and thus the loss of the flywheel effect begin to outweigh the benefits of lighter blades that start to spin faster in lighter wind, but stop sooner with the loss of wind? As to the birds, that is a good point, however, I was more interested in the affect on the climate when wind patterns are altered.I know that darn butterfly that flapped his wings in China last year caused us to have an unusually warm summer. >mild attempt at humor<
Louis, I would find it tough to believe that we've got enough wind turbines on the planet yet to have an affect on climate, which is macro-scale, although it's an interesting question whether they might have an effect on weather, which is a local phenomenon.
For sure, there are not that many in use to cause a major change in the climate, but the use of the word ""yet" implies there could be.
For sure, setting up a windmill directly in front of another windmill would be foolish, as the energy removed by the first unit will never reach the second. That said, what affect will removing <enter the energy amount of your choice here> have on the climate long term? I posed the question only as it is an unknown to consider as we search for alternative sources to meet the ever-growing power needs of society.
I had the same question--will the use of wind turbines get to a scale where what they are doing interferes with, or at least somehow affects, larger-scale wind patterns, i.e., climate. I suspect this has already been at least considered, if not studied yet.
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