Wind turbines extract kinetic energy from the air around them, and since less energy makes for weaker winds, turbines do indeed make it less windy. Technically speaking, the climate zone right behind a turbine (or behind all the turbines on a wind farm) experiences what's called a "wind speed vacuum," or a "momentum deficit." In other words, the air slows down.
The effect has implications for wind-farm efficiency. Upwind turbines in a densely packed farm may weaken the breeze before it reaches the downwind ones. It could even have a more general impact. If wind farms were constructed on a truly massive scale, their cumulative momentum deficit could conceivably alter wind speeds on a global scale (though how winds would change is complex—they'd likely slow in places and speed up in others).
Wind farms can also affect the local temperature. According to Somnath Baidya Roy, an atmospheric scientist at the University of Illinois, as a breeze passes over a wind farm, the turbines create an atmospheric wake where wind speeds drop and turbulence increases. The rotors spawn a set of eddies that mix air from above with air from below. The eddies can lift cool air and sink warm air or vice-versa. That turbulence could raise or lower local temperatures. In a paper published in 2012, one group of researchers studied areas over several wind farms in Texas and found that local surface temperatures had risen by a small but significant amount.
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In other words the supposed alternative wind farming will screw up the world even more! So go green, go nuclear!!!
And Remember Everyone!
Have fun, Have Nukes!
The last sentence is paradoxical: "...small but significant." I think the author must mean "measureable but INsignificant."
It's ridiculous to think that a wind farm would make it more or less windy generally, even though of course the space immediately in front of our behind the turbine will be different than if the turbine wasn't there at all. Such silly musings, to be preoccupied with such trifling matters, have we nothing better to do? If everyone gathered in one spot then jumped repeatedly, will we alter the orbit of the planet? Oh, I'm sure the effect would be "small but significant," in which case we'd crash into the Moon eventually.
How is a wind farm any different from a city of tall buildings in this regard?
@spark - in my experience in research, "significance" usually denotes a measurement or result that cannot be attributed to random error or bias
There is absolutely nothing paradoxical about "small but significant."
Quantum Mechanics is the current champion of small, and yet it has massively profound impacts on not just our lives, but the entire universe.
Basically everything you said Spark is off the mark.
It is not ridiculous to think that a wind farm would make it more or less windy. Quite the opposite. Thermal Dynamics actually demands that to get work out of a system must require removing at least exactly that much power. Add in that it is theoretically impossible to have a truly perfect conversion, and now you need to remove more energy than you got work out, losing much to an increase in temperature.
Now consider that the weather system is a chaotic system, and you realize that fairly small changes can have a major effect on local weather patterns.
With these 2, you can clearly see that this is not some trivial study because they had nothing better to do. It is incredibly important that we know just how much of an impact large wind farms can have on total weather patterns in the area. Many deserts in the world are created due to local weather preventing storm systems from reaching the area. It is conceivable that an overly large wind farm could move the weather enough to turn a fertile area into desert.
That's an extreme case just to show the point, but imagine an area that is borderline. Georgetown Texas for example is in a bit of a blind spot for the local weather, frequently getting missed by storms either going north or south of it. Not too far away, there is a series of sizable wind farms. What if those farms continue to grow in the wrong places? Georgetown could go from rarely getting storms, to virtually never.
KillerT: Tall buildings are a bit different because they do not actively remove energy from the system, only passively. However, they do in fact have a significant impact on local weather. For example, inside the city, the winds are increased due to the narrowing canyon effect. There are also micro clusters of changed weather due to the sun being blocked from some places, but shining on others. This creates a temperature and pressure difference, which is the source of wind.
So, they do change the weather, just not in the exact same way. I would also expect that yes, downwind of the city the wind would be reduced. I could be wrong there though.
Back to Spark: There is no such thing as entirely wasted research. The most mundane, trivial, and commonly known things can still lead to significant and important information.
Consider a room with a large number of people, such as a theater. Studies have shown time and again, that it is faster for everyone to get out by walking, rather than running. When people run for the exit, they create blockages , jams, and inefficiencies when trying to get out. When walking, they were more efficient, and able to follow each much closer as they walked out of the doorway.
Before these trivial tests were performed, it was common knowledge and basic instinct that running was faster. This was only true for the first few individuals, but actually negatively affected everyone after that.
VBwithME and zechio,
You mean some of these wind farms are a bad idea, and need to be taken down? That kind of significance? Otherwise we can fuss and fret about “efficiencies” forever. Which is what this article is doing, as indicated in the second paragraph.
I don’t think the matter has the urgency – nor importance – as how best to exit a packed theatre in an emergency, nor is this a matter of turning neighboring “borderline farmland” into deserts. I think it’s an exaggeration, if not alarmist, to make these particular analogies. Whatever side effects are caused by wind farms, they pale in comparison to the possible side effects of a nuclear reactor. Hello? These wind farms are a breakthrough in safe energy creation!
Yes, alarmist. VBwithME, you state “It is incredibly important that we know just how much of an impact large wind farms can have on total weather patterns in the area.” Incredibly important? Good grief. That’s alarmist and pompous. Would you prefer a nuclear reactor in your backyard – or a windmill? “Side effects” of wind farms are moot. I think this issue was settled before these farms came into existence. Wind farms are not altering the landscapes of America other than by their inherent unsightliness. I stick by my original comment.
Look I wasn't trying to take sides, just wanted to clear up your misunderstanding of the context in which the word "significant" was used in this article. Typically you will see significant used for something important, but statistically speaking it is used to explain that what is not due to chance
Do skyscrapers change the climate? Yep!
Does the flapping of a butterfly in China affect weather in the USA? Yep.
Is it bad? No one can say for sure. Give me 10,000 years and I'll be able to tell you.
Spark: You are misunderstanding both the point of the article, and my comment.
It is not to say that wind farms should be immediately torn down. The research is simply showing that wind farms may have a greater impact than initially anticipated. They are intended to be an alternative method of generating electricity with minimal impact on the environment.
The research however shows that in large quantities, they do in fact change the environment. This must be taken into consideration for the future, and it warrants significantly more research to determine the extent of specifics of the effects.
Also: I would rather have a nuclear power plant behind my house than a wind farm. Nuclear power is a safe method of generating large quantities of power with minimal impact. In fact, the deaths in the nuclear power industry are pretty much the same as wind power. Almost all of those deaths are due to neglected and/or old nuclear reactors. Newer designs are even safer, being completely incapable of melting down for example.
As you may guess from my supporting a nuclear powerplant near me, I am actually anti-alarmist.
Anyways, if we really want to do something about cleaning up our affects on the environment in the short term, there is only 1 option. A simple 3 pronged approach: First, replace primary power generation from coal with nuclear. It's the only one that is viable for prime generation everywhere. Next, continue to improve secondary generation: This means more efficient wind, solar, etc. Finally: Think long-term. Improve efficiency of all power usage, and put more effort into Fusion power.
I've been waiting for this study. A hundred years ago no one was saying "a couple parts per million CO2 will effect the climate". Sure it's a greenhouse gas, but its a weak greenhouse gas. Now the global warming alarmists are trying to convince everyone that this is warming the planet for the worse.
Because liberals like wind farms, probably due to the inefficiency, they are ignoring the small but significant effect on the climate.
Keep in mind, wind cools the planet, through the convection process, the movement of polar air down to the rest of the planet, etc... Now, we're blocking these winds to make electricity. Sure, it a very small effect right now. But, what effect a hundred years from now when millions of these windmills are spread throughout the planet? Can you see a "warming" effect? I sure can.
Of all the gas, gasoline, coil and oil burning, not counting the spent gases (CO2 and other pollutants) but just focusing on unused spent exhaust heat, I wonder to how this has change the environment.
Zechio, there have been deaths from wind farms? I know that nuclear power is safe (notwithstanding the tsunami in Japan 2 years ago and Chernobyl), but I didn’t realize wind power also posed a risk to human life. Still, I wouldn’t want a reactor in my back yard (granted TMI is just a few miles from me – and I glow in the dark).
stevePC, windmills are not blocking the movement of polar air from Canada. The warmer summers and winters have been attributed to global warming, not windmills. Where did you read that windmills are blocking Canadian air?
Windmills are awesome!
Spark, I'm not saying windmills are currently blocking Canadian air. But, as the article stated "Wind turbines extract kinetic energy from the air around them, and since less energy makes for weaker winds, turbines do indeed make it less windy". So, as we build more and more wind farms we are losing more and more of the energy of the wind, it is this energy (movement of air masses) that cools the planet. I'm thinking we must consider this now, not 100 years from now.
12, "CO2 and other pollutants", I love how people have been brainwashed. CO2 is not a pollutant any more then O2, N2, H20, etc.... Wait until the gov't wants to tax "pollutants" like CO2 (that'll be $0.02 for every respiration please).
There seems to be a lot of confusion about wind farms somehow making things more or less windy in the surrounding area, plus additional nonsense about kinetic energy, etc. When you blow on a pinwheel, and it rotates, does this “take the wind out of you” like a vampire might suck blood out of you? If you put a pinwheel in front of your face, that was balanced so that your normal exhalations caused it to rotate freely, you’re harnessing the existing potential energy of the moving air as it exits your nose. But does this cause your diaphragm to work harder, or you to have to breath differently? Of course not. Look at it on a bigger scale. The spinning turbines on wind farms are not affecting the source or strength or direction of the prevailing winds in the least, since the prevailing winds cause the turbines to spin and not vice-versa (i.e., the turbines are not powered) and, most significantly, the prevailing winds have a far greater effect on the existing environment, and determine its nature, than any “fluctuations” to this caused by the spinning blades. Please correct me if I’m wrong.
Here’s a good way to demonstrate this: imagine yourself suspended at the height of a turbine in a wind farm, but not in front of one of the turbines. You’d feel the wind that normally flows through that area, of course. Now imagine yourself suspended directly in front of one of the turbines. Would you feel the same wind, or would it be more or less? It’d be basically the same, even using a wind meter (assuming the turbines are in fact balanced to spin freely, but that could be measured directly and not rely on oddball suspicions about wind farms changing wind speed in area). Go back to the breathing on a pinwheel example. The air on either side of the pinwheel IS MOVING AT THE SAME SPEED because, of course, the pinwheel IS BALANCED TO ROTATE FREELY. The pinwheel isn’t ALTERING the movement of air as I’m exhaling. And, as with the turbines on a wind farm, the source, or final destination, of the wind is not altered – after all they’re not designed to do that (otherwise they should be redesigned – for the sake of “mechanical efficiency” that can be tested directly and not on “theories” that wind farms make it less windy).
But even if I’m completely wrong, there is wind basically everywhere, and it’s constantly changing. This is key: there are no areas unsuitable for farming that would be made suitable but for a “slight change in the local wind patterns.” No one is sitting on a windy field (or “borderline” area) thinking, if only it wasn’t windy, I could farm this field. For the reverse to be true is therefore so unlikely that it would have no bearing on current policies concerning their use.
One might wonder why we don’t attach numerous pinwheels to cars, to recharge the battery of an electric car. Am I on to something here?
Spark, let me try again. There is no free energy. Windmills are harnessing the energy of the wind. If you use this energy, then the energy is no longer in the wind, simple physics.
Wind has kinetic energy, Ek=½ mv², it has a mass and it has a velocity. Wind gets this energy from the heat of the sun. This heat is converted to wind (hot air rises/ cold air falls and all that).
Windmills then convert this energy to mechanical energy (spinning of the blades), the blades convert this energy to electricity (spinning of the turbine).
This energy is not free. The energy of the wind must be less on the downwind side of the windmill. Windmills are not 100% efficient, so there is wind on the backside as well, but it MUST be less.
The windmill does not rotate freely, it must have resistance in the turbine in order to convert the energy to electricity.
The windmill does not stop or effect the source of the wind, but, it slows the mass from reaching its final destination with the same energy (or mass of cold air, if that helps).
Your pinwheel analogy doesn't really work. The pinwheel doesn't effect your breath, you are correct there, but it does slow the "wind" behind it. A pinwheel is very light and very low friction, so the effect may be slight, but it is there. Try lining up 20 pinwheels one behind another. If you blow on the first, will the last one spin the same as the first in line?
Your pinwheel on a car idea, not gonna work either, if you attached a turbine to the pinwheel to generate electricity it would conceivably work. But the amount of energy created would be less then the amount of extra energy needed to accelerate the car due to the pinwheel.
SteveCP, wind is free. This is like arguing that the sun will burn out faster the more solar cells we put up! The wind is free. Of course there's a price to R&D and manufacturing and installing and maintaining wind farms, and deliver the electricity, but that's not the point.
The windmills are not lined up, they're staggered. Obviously if they're lined up front to back, very close, there would be a cumulative effect to diminish the air flow, if the turbines are not balanced to spin freely as you say. But the air flows through the blades, freely, the slowing effect would be slight. People who live near wind farms are not worried about variances in wind speeds that may be caused by wind farms.
The surface area of the blades is NOTHING compared to the volume of air travelling over the terrain, and that's just along the surface of the earth, at the plane of the wind farm. The air mass extends straight up a few miles. The effect of wind farms on the Earth’s winds is practically 0, in light of the vastness of the air masses that travel over the land.
spark, your first two paragraphs - you're just not getting it. OK.
Your last paragraph - "NOTHING compared to volume" and "effect ...is practically 0". This is my point. Right now, we believe the effect is practically 0. But it's not zero and if we continue to build more, the effect is greater.
If we compare this to the burning of gasoline for our cars. What if one hundred years ago, someone said "hey, burning all this fossil fuel is going to add 40-50 parts per MILLION (.004%-.005%) of CO2 across the vast, vast atmosphere of the Earth" I guess we could have said the effect is practically 0. Do you believe the effect is 0?
I can not understand why that guy calls himself "spark" he might have a lot of fine characteristics, but "bright" is certainly not one of them.
Perhaps Spark is worried if we energize all the windmills we might cause the Earth to stop spinning or worse revolve backwards, lol.
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