Why Wind Turbines Have Three Blades
There is a lot of bad information here, and it appears there are others in these who are also better informed than the author. Let me just hit up a couple of points that are fundamentally wrong, though.<p>- &quot;Conventional wisdom says wind farms should have their turbines placed in such a way that they don’t interfere with each other, the fear being that placing one turbine too closely in the shadow of another will reduce the efficiency of the showed turbine.&quot;
True, and this is why we have wake models based to predict the losses from other turbines and optimize placement.<p>- &quot;The rule of thumb, then, is that turbines be placed no closer than seven diameters apart. Keep that number in mind.&quot;
Not true. You may find that a 7x7 array is relatively common in offshore applications, but a typical onshore application is more likely to be between 2-4 diameters apart in a row, with rows 7-13 diameters apart front to back.<p>- &quot;Oh, and turbines are placed seven diameters apart. That’s it, no CFD.&quot;
Wrong. But CFD is generally computationally complex, so we usually use models with reduced fluid dynamics equations to make it possible to iterate quickly. See previous comment about wake models.<p>- &quot;In some cases wind farm automation can cost as much as the turbines, themselves.&quot;
I&#x27;d like to see these magical cases. A typical 2 MW turbine costs $2 million to purchase, and about $3-3.5 million total as part of an overall project of 50 turbines. SCADA is a minor fraction of this, as is operations.<p>- &quot;Shorter blades are stronger than longer blades, so the Lipps turbines can operate in faster winds.&quot;
This is a non-issue. There are very few sites in the world that require even the highest wind speed turbine designs; most of the world is less windy, and the majority of sites benefit from using turbines designed for lower winds.<p>- &quot;Use permanent magnet generators and the turbines could be allowed to run 24&#x2F;7 in any wind with no computer control required at all, leading to more production at even lower cost.&quot;
Computer control of turbines is a non-issue, and the cost is minimal relative to the raw materials cost of the machines.<p>- &quot;This is because they use alternators that consumer electrical power to energize their windings so there is no point in turning-on the alternator (energizing those windings) until there’s enough wind to generate a net positive amount of electricity.&quot;
This is only a little bit correct, and mostly not. Wind turbines by design generally need to be connected to the grid to run, but winding energization is not why they don&#x27;t start generating until there is enough wind. Turbines are generally on all the time, and typically consume anywhere from 10 to 50 kW at idle. And I don&#x27;t know why he&#x27;s using the term &quot;alternators&quot; to describe the turbine generators. The most common generator type is a doubly-fed induction generator, but squirrel cage induction generators, permanent magnet generators, and synchronous generators are often used. Usually turbines are connected to the grid through power converters which allow them to run at various speeds while remaining electrically synchronized with the grid.<p>- &quot;Remember the diameters are smaller so instead of hundreds of turbines we’re talking about thousands of turbines for the same wind farm. Imagine a field of mature dandelions.&quot;
This is actually a problem. When you can get 100 MW with a 50% capacity factor by building 50 machines in one township in Nebraska, why would you want to build 1,000 machines instead? How is that less complex?<p>- &quot;Try breaking into the industrial wind power business without at least $1 billion in capital. It can’t be done. The incumbent companies like it that way, too.&quot;
Manufacturing is capital intensive. News at 11.<p>- &quot;Lipps wind farms could be closer to cities and therefore have lower transmission losses, further increasing power output.&quot;
Wind farm placement is about where the wind resource is. It&#x27;s an economic decision.<p>- &quot;The result of all this not starting and then stopping is that throughout the year an average workload of 23 percent is reached by inland wind farms, 28 percent for coastal farms and 43 for off-shore.&quot;
I have to assume his &quot;average workload&quot; here (a term I&#x27;ve never heard in the industry) is equivalent to capacity factor, which is the ratio of actual energy produced to the maximum possible. Most new projects in the windy areas of the US have predicted capacity factors of greater than 40 percent. High wind losses are typically very low, and online time is typically very high.<p>- &quot;China will build the heck out of those smaller blades.&quot;
China is also building the heck out of the larger blades. China has more wind capacity installed than any other nation.<p>- &quot;And no insane cows, either. Cattle can’t be pastured under wind farms because the motion of the turbine blades and especially their sound drives cows crazy.&quot;
Tell that to these cows <a href="https:&#x2F;&#x2F;www.flickr.com&#x2F;photos&#x2F;ashcreekphoto&#x2F;7793429362" rel="nofollow">https:&#x2F;&#x2F;www.flickr.com&#x2F;photos&#x2F;ashcreekphoto&#x2F;7793429362</a> (did he even do an image search before posting that? I&#x27;ve built wind projects on cattle ranches.)<p>Why does this post use such an old, crappy US wind map? Why not the newer DOE wind maps available at <a href="http:&#x2F;&#x2F;apps2.eere.energy.gov&#x2F;wind&#x2F;windexchange&#x2F;wind_maps.asp" rel="nofollow">http:&#x2F;&#x2F;apps2.eere.energy.gov&#x2F;wind&#x2F;windexchange&#x2F;wind_maps.asp</a><p>I&#x27;m sure I could go on, but this is just a fundamentally misinformed article. It&#x27;s trying to make an aerodynamic argument (which I am not qualified to judge) using a mess of bad or incorrect information.