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By Jim Wiegand, wildlife biologist


Editor’s note:  Several massive wind farm projects are proposed for San Diego’s East County and neighboring Imperial County. The County is now considering a wind ordinance to make it easier to build wind farms.  But is the wind industry deceiving the public on bird death rates, particularly from new and larger turbines? 
Under each giant turbine with a 31,860-square-foot blade sweep, the wind industry only searches for dead birds within a 75 meter area. By contrast, under a small turbine with only a 1,658 square foot blade sweep, a  50 meter search is done.  The blade sweep area is nearly 20 times bigger for giant turbines than for small turbines--but the industrly only looks  for bird carcasses in an area 1.5 times larger.  How many slaughtered birds are not being counted? 
“…New larger turbines are far more dangerous to the golden eagle and wind turbines kill the indigenous species ...Data shows that there is a direct association between the number of fatalities found in relation to turbine size [ie, the industry claims lower mortality rates with larger turbines]. It is an illusion, because from the highest number of fatalities found in the studies down to the lowest shows progressively smaller search areas for each of the five larger wind turbine categories.”
– Jim Wiegand
December 12, 2011 (San Diego’s East County)--A few months back, it was disclosed through media that the Altamont Pass Wind Resource Area in northern California was repowering with new, safer turbines. With their new turbines Altamont was going to drastically reduce the bird mortality rate by 80 percent and raptor deaths by 67 percent. We were led to believe that this major upgrade was going to drastically reduce the number of bird kills in the Altamont region while increasing energy production. This highly publicized move was received as good news across the world, because thousands of eagles and tens of thousands of other raptors have been slaughtered at the wind turbines of Altamont Pass.                                                                                   
Over the years I have seen the wind industry answer to its turbine mortality problem:  declare as little as possible, change environmental laws, keep every meaningful regulation off the table, hire an  army of  biologists that will fortify any wind industry position and install wind turbines  just about anywhere the wind blows. The money has always won and the golden eagles and all other raptors have lost. To top it all off, the mitigation process for all this madness amounts to nothing more than a system of  bribery and  deliberate inaction.
I am well aware of the wind industry's methods of operation did not understand how these new turbines could safer.  The turbine designs haven't really changed, they're just bigger and their blade tips now move faster.                                                                 
For this critique I poured through decades of reports and studies on Altamont Pass to see if there was any credibility to what was written up in the media.  I now have a different story to tell. I believe everyone who reads this will not think of Altamont Pass or any other wind farm, in the same light again. 
The industry has compiled a set of numbers to illustrate that  the larger turbines used for the repowering of Altamont do appear, at first glance, to be safer.  These numbers were presented in ratios comparing Fatalities/ Per 1 Megawatt /Per Year. I will only illustrate and discuss a few of the key numbers that refer to the media reports. These are the target species of raptors and those used for all native birds.  The lower set of mortality numbers are for  target raptors:  the Golden Eagle,  Red-tailed hawk,  American kestrel, and the Burrowing Owl. These are the raptors which are killed in the highest number each year.  The higher set of mortality figures represent the many species of native birds killed at Altamont over the years.
40-65 Kw                4.035 raptor fatalities/MW/year       11.00  bird fatalities/MW/year
95-200 Kw              3.243/ raptor fatalities MW/year      8.140 /bird fatalities MW/year
250 Kw-400kw       1.579 raptor fatalities /MW/year      4.111/bird fatalities MW/year
660 Kw                     2.117 raptor fatalities /MW/year      3.512/bird fatalities/MW/year
1 MW Buena Vista  0.748 raptor fatalities /MW/year      2.389/bird fatalities MW/year  
The industry data that was most favorable was derived from mortality studies undertaken at the newest installment of Altamont turbines called Buena Vista and then compared to other turbine sizes. They represent the large turbines the 1 MW category.                                                                                                                                          
These are impressive numbers and it appears that Altamont is on its way to reducing yearly mortality and living up to the settlement agreement made with the Audubon society, Californians for Renewable Energy ("CARE");  and Attorney General ( People of the State of California), to reduce mortality.                                                                                
But numbers are one thing and reality is another. I will show why the agreement made to reduce mortality at Altamont is not being met and discuss why mortality is about to get worse.
Rated Capacity and Actual Energy Production
Altamont pass has a rated capacity of 580 MW. This number represents the theoretical total energy output of their 5000 or so turbines under high wind conditions. Every turbine depending on its size also has an industry given "rated capacity".
All the mortality numbers from Altamont that were used to proclaim the larger turbine as being safer, were derived by using comparisons to "rated capacity".  By using bird mortality and equating it to rated capacity, it creates a deception or trick of numbers.  Rated capacity is a subjective wind industry or turbine manufacturer  figure that refers to maximum energy potential of a turbine at a particular wind speed. The term rated capacity is so vague that it should NEVER be discussed in any mortality impact studies to protected species.                                                                                                        
For example when  actual energy production from individual turbine sizes is compared to bird mortality the numbers take on a whole new meaning.  When I ran the numbers the mortality data went up on the new larger turbines as much as 2.6 times.  This figure was derived calculating estimated  average wind of Altamont pass ( 12.5 mph) and checking it against actual field test data from the manufactures.                                                                               
For the sake of comparison, the actual energy production data for the old 65KW  Windmatic wind turbine compared to the much larger Mitsubishi MWT-1000A wind turbine,  show us that 7.4 of the smaller turbines will produce the same amount of energy at 12.5 mph winds. Yet because the term rated capacity( 65KW and 1MW) is used, the larger Mitsubishi turbine is being compared to the mortality figures of 19.2 of the older turbines instead of 7.4.  If this inflated 2.6 ratio is plugged into the industry numbers it drastically lowers the comparison mortality numbers  for the smaller 40kw-65kw class of turbines.
Keep in mind these are the turbines we are told are the most dangerous when compared to the new 1MW turbines. 
If the bigger 1MW turbine is only going to sit in average winds of 12.5 mph, it should only be rated in the 450-500 kw range when compared against the smaller turbines. Similar discrepancies exist in comparisons with all the different turbines in use at Altamont. There is nothing scientific or conclusive when using the term  "rated capacity" in calculations.
I know the State Of California is well aware of the problems with the term "Rated Capacity"  because twenty years ago the California Energy Commission made the following statement about rated capacity: "Because the wind industry does not yet employ a standardized turbine rating system, much of the data reported is not directly comparable. Turbines are tested under different conditions and rated at widely varying miles per hour specifications. Evidence of the problem is indicated by the lack of correlation between blade swept area and turbine KW specifications."                                         
The fact that the wind industry even uses rated capacities in their correlations with mortality leaves every bit of its data in question.
Instead, facts that should always be discussed in every scientific mortality study are the rotor sweep area of  turbines,  hours in use each year while operating at kill speeds(60-250 mph tip speed),  and placement-- because these are the primary wind turbine factors that slaughter our birds.                                                                                                                                    
Currently there is no standardized data available from Altamont Pass and all other wind facilities across America that equates actual energy production to raptor and bird mortality. If one understands the magnitude of what I have just presented, then it becomes obvious that none of the wind industry mortality studies that have used rated capacity comparisons have any credibility. Rated capacity, that vague term of potential, is also used in another deceptive manner:  to embellish the energy projections of wind farms. 

In the end, with these new turbines going into Altamont, more energy will be produced and that is the real reason why they are repowering. It is not for the birds and never has been
. It is for the energy. More energy will be produced at 300 feet up in the sky with far more rotor sweep where these new turbines reach into stronger winds. Likewise if proportional numbers of the old turbines(now on  60- 80 foot towers) were placed up at 300 ft, they too would produce far more energy.
Even so, there are far bigger problems with the wind industry mortality studies, their conclusions, and the media hype.
Proportional Rotor sweep and Search Areas
In order to get the mortality data,  an area around each turbine must be searched. If we compare the areas searched between the different turbine types the results are shocking especially when comparing the search areas of the 1MW turbine to the smallest and supposedly most dangerous 40-65 KW turbines.
rotor sweep area  40-65 Kw       154 sq meters/1658 sq ft            50 meter search

rotor sweep area  95-200 Kw   approx. 350 sq m/1734 sq ft         50 meter search

rotor sweep area 250 Kw-400kw  approx. 800 sq m/ 8611 sq ft   50 meter search 

rotor sweep area  660 Kw                     1734 sq m/ 18664 sq ft    60 meter search 


rotor sweep area 1 MW Buena Vista    2960 sq m/31,860 sq ft      75 meter search                                                                                         
Published Scientific reports claim declining fatalities in the new larger turbines installed at Altamont but the data also shows something else if you look close. The data shows that there a direct association between the number of fatalities found in relation to turbine size. It is an illusion because from the highest number of fatalities found in the studies down to the lowest shows progressively smaller search areas for each of the five larger wind turbines categories.
The area searched for each of the smaller Windmatic turbines is 50 meters out from the base of each turbine.  The area searched looking for bodies around the 1 MW turbines at Buena Vista was 75 meters.  Since the 1 MW turbines are actually 19.2 times bigger and more than 180 feet taller, the data illustrates a huge discrepancy in comparable search area sizes. The search area for 19.2 of the smaller turbines (which reported the highest mortality)  was  149,935 square meters .  Now if we look at the total area searched for the 19.2 times larger  1 MW turbines,  it is just 17662 square meters
A total single search of all the 38 turbines  said to "safer"  in the Buena Vista wind project, covered  671175 square meters. In contrast the total search area using the same rotor sweep equivalent of the 726  40-65KW  turbines was 5,699,100 square meters of land.  A difference of  5,028,735 square meters, or  almost  2 square miles.
The mortality figures given by the industry for the 1 MW turbines were derived from  search area equivalents 8.5 times smaller.  The discrepancy is huge. The new larger turbines with lower claimed fatalities had bird and bat mortality searches that were 26 million less square feet every time searchers looked through the turbines.  So what does this all really mean?  That if you do not look, you will not see.
The size of search areas is very important because wounded birds with severed limbs can travel great distances and live for days before dying. Hundreds of thousands of people worldwide have tuned into YouTube to witness a Griffon Vulture  knocked out of the sky by a wind turbine. Had this grounded bird not been picked up by the cameraman's friends, this grounded bird would have traveled for a week or two before dying.  This is a common scenario with wind turbine collisions.                                                                                                                            
As anyone can see  from the data above, undersized search areas will miss a large percentage of causalities. In addition smaller birds hit 300 feet in the air by 200 mph blade tips, can fly like a baseball upon impact beyond the small search areas. Virtually every bird or raptor found at a wind turbine facility should be classified as a mortality, but because of ridiculous study designs, this does not happen
All Native Bird Comparison Data                                                                                                    
The new turbines were said to drastically reduce the bird mortality rate by 80 percent. This statement is not true. Not only are the all native bird figures wrong from the result of  using distorted comparisons of rated capacity, rotor sweep, and search area sizes, but birds species that do not use the habitat, were used to create the low Buena Vista number of 2.389 bird fatalities/per MW/ per year. 
Bird species that do not live in or use the habitat should not have ever been used. I've walked the Buena Vista habitat. The habitat where the Buena Vista wind turbines are placed, is a treeless semi desert grassland (see images).  You will not see wild turkeys, flickers, scrub jays, pelicans and many of the other bird species that were used to build the 80 percent reduction number. This is another trick of numbers used to create the safer turbine myth.
More Turbine Comparison Data Problems
Hidden in the numbers are several other facts that completely change the widely published repowering conclusions. With the largest 1MW turbines, is the terrible news that the golden eagle death rate went up over all other wind turbine categories from .043 fatalities to .084 per MW /per year. Even with the many flawed comparisons and conclusions the death rate still nearly doubled when compared to the 40-65 kw turbines. When accounting for these flaws, the death rate for the golden eagle becomes even more alarming because it easily escalates mortality to over 4 times as many golden eagles killed with the so called safer turbines.                                                                                                                                                
Lastly it must be pointed out that the these same 1 MW Turbines put in other locations of  Altamont pass with a more diverse  habitat, would kill far more raptors, birds, and bats. In other words the bird and raptor mortality reported would have been higher in nearly every category except for those species like the Horned larks and Prairie Falcons that prefer this semi desert habitat. The death list from the Buena Vista turbines shows that their mortality numbers went up.                                                  
The only reasonable conclusions that can be made from the Buena Vista Mortality studies is that the new larger turbines are far more dangerous to the golden eagle and wind turbines kill the indigenous species from within the habitat where they are placed. There certainly is nothing conclusive about the turbines being safer.
The Stark Reality
One of the reasons the new turbines are so dangerous to eagles is because the placement of the Buena Vista turbines now has the highest concentration of wind turbines in all of the Altamont region.  For any bird species that pays a visit to the Buena Vista Wind farm, the chances of coming out alive are the worst in all of Altamont. Now within this .85 mile square mile area, anything that flies must face 1,205,132 square feet of air space with spinning turbine blades. Their blade tip speed is 210 mph when spinning at 19.8 rpm.  The Buena Vista section of Altamont Pass has more than three times the density of spinning blades (rotor sweep) found anywhere else in the entire Altamont wind resource area.
                                                                                                                                           For the Buena Vista project 179 older turbines were taken out and this repowering project  added 441,320 more square feet of rotor sweep to the previous total. When the original 179 turbines were dismantled, they also did not sit on .85 square miles, they were spread out over an area of 3.9 square miles. The untold truth is that the Buena Vista wind farm is now the most dangerous installment of turbines in the entire region of Altamont Pass and it is going get worse.
The future                                                                                                                                     
With the repowering Altamont the total rotor swept area for all the turbines is on a pace to be increased by millions more square feet.  New 430 foot-tall turbines are now being installed that are 44 times bigger than the early 65KW turbines. I want the people in the Bay Area,  to understand that they have been hoodwinked by the industry. Altamont is not repowering--but undergoing a massive expansion hidden behind a bird friendly sales pitch.   
They need to pay attention to the increase in rotor sweep that is headed their way. The repowering with just 500 2.3 MW turbines will be the rotor sweep equivalent of  adding 12,000 more of the smaller wind turbines to this wind resource area of 5000 turbines.
The Altamont region is a critical migration corridor and winter habitat for raptors and many species of birds. If  nothing is done, the decades long blood bath at Altamont will not only continue but it is destined to get much worse.
Deadline for public comment on the County's proposed wind ordinance is December 23. For details, see
The opinions in this editorial reflect the views of its author and do not necessarily reflect the views of East County Magazine.  To submit an editorial for consideration, contact


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Wind industry disclosures have ALWAYS avoided Tip Speed

Wind industry disclosures have ALWAYS avoided Tip Speed

It is now known that the early Altamont and Tehachapi wind turbines were mass killers of bird and bats. The industry hid this for years and is still hiding the majority of fatalities at all wind farms. Despite what you read or hear from the industry, the new large turbines are NOT SAFER for birds. They are far more dangerous. With the old smaller turbines, their blades turned faster at72-80 rpm, but the tip speed for these blades was only about 125 mph (184 ft sec). The tip speed was far lower because the blades were only 22 ft long. The new huge turbines have blades 150 ft long or more and when spinning at 20 RPM, have a blade tips moving at 314 ft per second or 214 mph.

The blades of the turbines with lower rpm not only fool the public but also fool birds and eagles more easily. This is because they can see right through these huge illusive openings between the blades and think they can fly through them to what they see on the other side. The industry has fraudulently capitalized on this illusion in the media. The new turbines are also more dangerous for another reason. These turbines spend more time rotating throughout the year. They are made with lower cut in speeds, so they start turning at lower wind speeds. This means that each turbine is more lethal to birds and bats because they spend more time with their blade tips ripping through the air.

It is easy for anyone to figure out tip speed once you know the blade length, diameter, and maximum rpm. Here is the math for the so called new generation safer wind turbines. They generally spin at 16-20 rpm 1) A single blade on a 300-400 foot turbine with 150 foot blades slowly moving at 20 rotations per minute will equal a circle with a 300 foot diameter. At 20 rotations each blade tip is moving 20 x 300 x 3.14 feet per minute =18840 feet per minute divided by 60 which equals 314 ft per sec or 214 miles per hour.