The following article is cross-posted from the Barnard on Wind blog with permission of the author, Mike Barnard.
Anti-wind lobbyists claim more than 1 in 20 wind turbines permanently inactive; they're wrong, as usual.
There’s an anti-wind energy myth floating around that refuses to die. The most recent sighting was in the official policy of an Australian political party, the Democratic Labour Party of Australia.  What is the myth?
That there are 14,000 permanently inactive wind turbines out there somewhere.
That last word, ‘somewhere’, is used advisedly. The 14,000 number has been applied to the entire world, the continental United States and the confines of the state of California. It’s a pretty flexible number and a pretty flexible and well-traveled myth. That last version, that there are 14,000 inactive wind turbines in California alone, was the one that the Australian political party enshrined in its policy on wind energy.
Tory Aardvark, the climate-change denying bastion of disinformation, likes the U.S.-only version, although its blog entry quotes the origination of the myth which talks about the world-wide number, so Aardvark manages to get it wrong twice in one post.  This level of inaccuracy is fairly typical of that anonymous blog, so it isn’t surprising.
The myth started with Andrew Walden, a Hawaiian anti-wind activist, in early 2010. He wrote an article starting with the Kamaoa Wind Farm in Hawaii that was heading for decommissioning and repowering and pulled the number of 14,000 permanently inactive wind turbines out of … somewhere.
In the best wind spots on earth, over 14,000 turbines were simply abandoned.
He doesn’t make any effort to show how he arrived at this magical number. He doesn’t list sources. He doesn’t show calculations. He just comes up with 14,000 for the world through some magical process. You would think that the lack of any supporting evidence would prevent people from quoting and then exaggerating even his already wildly exaggerated claim. However, the quality of evidence doesn’t matter in the global warming denialist and anti-renewables crowd, what matters is the quotable claim.
So, what is an accurate number or methodology for determining the current number of permanently inactive wind turbines?
A more realistic maximum number is at most 1% of installed wind turbines — perhaps 2,000 wind turbines — and perhaps 0.1% of generation capacity. And the number of permanently inactive wind turbines is diminishing as they are replaced with working modern turbines.
The sensible methodology to arrive at a very conservative — aka, unreasonably large but defensible —number of permanently inactive wind turbine has a few steps.
– Calculate the worst-case ratio of inactive wind turbines
– Determine the total number of wind turbines
– Calculate the worst-case scenario using the ratio
– Assess generating capacity implications
What is a good way to calculate the worst-case ratio of inactive wind turbines?
There are about 5,000 wind turbines installed at Tehachapi Pass Wind Farm and of these, approximately 100 are inactive. This ratio is 2%, and is at one of the oldest operational wind farms in the United States, where massive tax breaks combined with immature technology have created one of the highest ratios of inactive to active wind turbines in any location. The majority of the permanently inactive wind turbines were built in the 1970′s and are very old technology. Of course, the inactive wind turbines are being replaced with new generation capacity as part of the Tehachapi Pass Renewable Transmission Project , so the number of dead turbines is going to drop substantially.
How many wind turbines are there?
According to the Global Wind Energy Council (GWEC), there are just under 240,000 working wind turbines as of Q1 2013.  14,000 wind turbines permanently inactive would represent about 6% of the total installed base being inactive today.
What does this imply for the possible number of inactive wind turbines?
The number of 2% is likely much higher than the world wide reality, but if true would represent roughly 4,800 permanently inactive wind turbines.
A more reasonable but still very conservative upper limit of 1% would bring that down to a maximum of 2,400 permanently inactive wind turbines.
What percentage of generating capacity would these represent?
The inactive wind turbines would be much smaller than the typically 1.5-MW to 4.5-MW turbines currently installed, as typically it is older wind turbines that are out of production. The average wind turbine size in 1990, about 20 years ago or the lifespan of a wind turbine, was 200 KW. A little simple math says that conservatively these inactive wind turbines might represent 0.1% of total wind generation capacity.
Average wind turbine size in KW sold in different countries, source BTM Consult 
Are all wind turbines that aren’t spinning permanently inactive?
One thing sources who inflate the number of inactive wind turbines do is mistake temporarily inactive wind turbines for permanently inactive ones. There are many reasons why a wind turbine might not be spinning despite the presence of wind, and the majority of these are in keeping with good grid management techniques.
So, 14,000 permanently inactive wind turbines world-wide is gross hyperbole at roughly four times the worst case scenario, and becomes close to an order of magnitude of inflation when compared to a likely scenario. 14,000 wind turbines in the USA is laughably unrealistic; the US has about 20% of installed wind generation, so a more likely maximum number is 400 small, old wind turbines around the U.S. California is just funny, as there are about 14,000 wind turbines in total in that state, so 100% of them would have to be rusting in place for that claim to be true.
What’s the verdict?
14,000 is a number that has been conjured from thin air by an anti-wind advocate for rhetorical purposes. This type of shoddy and sensationalistic tactic is unfortunately typical.
In the meantime, Hawaii, where Walden saw an inactive wind farm and created his fantasy figure, is putting up more wind farms because they continue to make economic and environmental sense. Most jurisdictions are seeing replacements of older and inactive wind turbines with modern technologies., 
Paul Gipe’s excellent debunking: Debunking Anti-Wind Myth of 14000 Abandoned Wind Turbines in California
This material originally developed on Quora at: http://www.quora.com/How-many-
Fact check: Oops, wind farm performance stays strong, March 7, 2013
Fact check: Study on turbine lifespan 'just more anti-wind propaganda', December 24, 2012
In with the new: Older California turbines being replaced, April 16, 2012