US Offering $45M For Huge Wind Energy Test Bed 91
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samzenpus
from the blow-baby-blow dept.
from the blow-baby-blow dept.
coondoggie writes "On a day when one of the largest wind farm plans bit the dust, the US Department of Energy is offering up a five-year, $45 million grant to design and build a large dynamometer facility for testing 5 to 15 MW rated wind turbines and equipment. The DOE says such a facility is needed as the US has fallen behind other countries in the race to build ever-larger wind turbines for energy production. According to the DOE, the average size of wind turbines installed in the United States in 2007 increased to roughly 1.65 MW. Additionally, turbines already developed range in the 2.5 MW to 3.5 MW capacity sizes; with plans being developed for even greater power ratings. The larger wind turbines have outpaced the availability of US-based testing facilities, the DOE stated."
Re:Why? (Score:5, Informative)
IANAA (Adult, yes) Nuclear is much more efficient when compared to wind farms, but nuclear energy hasn't been developed enough for it to be used as a main energy source.
Someone should tell that to the French. Nuclear reactors provide more than 75% of France's power requirements. [world-nuclear.org].
Re:I find this hard to believe... (Score:3, Informative)
I suspect the power output is only a part of it. More important (as pointed out above);
- at what wind speed does it break down?
- if you run it at X high speed for Y hours, and small cracks form, how many more hours can you run it before it breaks? This is important e.g. if there's been a storm - how quickly do you need to send out a maintenance crew, or switch off the turbines?
- how is it affected by ice? how is it affected by flying plastic bags, or birds?
- if you want to compare 25 different designs for each of the above, how can you make sure they all experience the same input, so the output is comparable?
Testing in the wild is sensible but doesn't provide the quality of data needed.
Re:Why? (Score:3, Informative)
If you look closely, you will see that they also provide the U.S. more electrical generation than France has.
Dynamometer != Wind tunnel (Score:2, Informative)
Most of the posters seem to be under the false impression that this will be some huge wind tunnel facility. One of the difficult problems in designing a wind turbine is that the shaft turns very slowly, but electrical generators operate much more efficiently at higher shaft velocities. With the sort of dynamometer they are talking about, you use a very large motor to spin the generator (and possibly the attached drivetrain) and measure how its efficiency throughout its speed range.
Re:Go for it. (Score:3, Informative)
Well, here in Spain we already produce 20% of our electricity needs with wind, and it wasn't very hard or ultra-expensive:
https://demanda.ree.es/demanda.html
Re:So if I understand this correctly... (Score:2, Informative)
Having just visited a wind farm today, I can tell you that the gearboxes are what fail most often. The wind facility I visited had 44 older wind turbines (starting from 1998) and those gearboxes cost around $150,000 to $200,000 plus a significant amount for the cranes and man hours ($1000/day for the large crane required + $10,000 setup and $10,000 tear down, and they can only operate in low wind conditions). Those gearboxes, however, are supposed to last, IIRC, 10 to 15 years, but typically last less than 5, simply because of the stresses caused by starting and stopping (according to the mechanic there).
The NWTC is putting in a test gearbox at the same site to collect data for (hopefully) a year, but I really don't know anything about that facility. I guess they don't have what the DOE is looking for here?
Re:So if I understand this correctly... (Score:2, Informative)
Disclosure 1: I read the article.
Disclosure 2: I work at a wind turbine blade testing facility.
First point: the article speaks of the drive train, so the blades are not attached. The blades are *HUGE*, so that approach would be insanely expensive compared to the usual approach.
So, the usual approach is to test the parts separately, and to test the connections of the parts. When the parts can handle the load, and the connections can handle the load, and the support can handle the load, then the load can be safely transferred from the parts to the support.
a) The smart approach is to apply loads equivalent to that of the uncontrolled environment, increased with a safety factor. You can do that in the controlled artificial environment. This way, you abuse the parts more than what nature will deal out.
b) The tests should include fatigue tests. Since it is economically unfeasible to do a 20 year experiment, the testing frequency and amplitude are increased such that the cumulative damage in the critical spots is equivalent. Then the test is executed at a level augmented with a safety factor. So, yes, the varying aspect is tested.
c) I am not in the business of testing the drive train; however, depending on the construction of the turbine, the hard gusting winds from off angles that you speak of, are considered. I expect most of that load is carried by the bearings that carry the turbine hub, and that the remaining part is taken by the drive train. These loads are known, and thus can be tested. Moreover, risking the dyno as a test subject is kind of the purpose of the test: If it breaks then there is a flaw that needs addressing.
d) I agree that the test conditions are not the real world conditions. I do not agree that testing can be done only under real world conditions and that results obtained under testing conditions cannot tell anything about real world behaviour. The essential part here is the mapping between the real world and the test conditions. For instance, one could observe from material tests that doubling the load reduces the number of load cycles to failure by a factor 8 (I am pulling figures from thin air here to support my reasoning, however, one may look up the literature to find the proper figures. They'll support my reasoning). So, by doubling the load, we can test 8 times as fast. However, it is known that the UV light from the sun degrades the resin over time. So, in reality, the blade may not be as strong at the end of its life as the test specimen at the end of the test. These kind of influences must be taken into account. And again it is done with *rimshot* a safety factor.
e) As far as I know, every design is tested. Most of them by simulation, and some (including all designs going in production) of them by physical test.
The usual cycle is to do the engineering design, do simulations, improve, rinse, repeat, until a satisfactory design comes up. Then build an expensive prototype, which most likely passes the test, as the failure modes are known from the simulations and designed to be outside the operating envelope. This adds the following purpose:
f) Test the prototype to show it complies with the requirements.
One of the great experiences of my job is to see a blade fail at the predicted spot at the predicted load in the predicted way. Another is to see it fail in another way, and being able to spot what cause was missed. It is akin to the satisfaction of discovering and eliminating an important bug.
Re:Why? (Score:1, Informative)
Bigger turbines produce more power. No, not just like that. The sweep area of the blade is related to the amount of power. Since area=pi*r^2, then power=pi*r^2 (or at least the power from the wind available, when comparing a big turbine to a small one). You can get more power from one big turbine, than from three or four small ones, and also you only have one turbine to maintain, not three or four.