A rumor in my region states that a wind turbine consumes far more energy while being built and setup than it can produce in a lifetime.
The debate is about modern, freshly built turbines in Southern Germany.
Is there evidence that this is true?
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the average windfarm [sic] produces 20-25 times more energy during its operational life than was used to construct and install its turbines. It also found that the average "energy payback" of a turbine was 3-6 months.
The German federal environmental protection agency says that wind turbines produce back the amount of energy that was consumed during production after 3 to 7 months.
Siemens analyzed its wind turbines and found that the energy amortization period is about 5 months for onshore facilities and about 10 months for offshore farms. This considers not only the cost to produce the turbines, but the entire lifetime energy cost, including maintenance, dismantling, etc.
Given there's much talk about the 2010 study, here's a 2013 one. It mainly expand the other one, by:
"Tweaking the lifetime": very low ones were assumed for conventional plants (also including deprecated centrifugal enrichment tech for nuclear)
"Counting all output", even if not needed: i.e. including the need for buffering (aka "backup" in case of variable energy sources)
With respect to just wind power, we can see they offer a similar mean figure of around 16~19 (which as Weißbach notes is massively dependent on the place turbines are built). If you consider the aforementioned later caveat, this gets double halved, but still we are quite above "energy sink" levels.
Further anyway (depending on whether your actual point is about wind energy in general, or "to be built new turbines") EROI further scales up, given most common newer installations average size is almost two times an E-66.
The roi depends on the windmill, and it could be bigger than 3-6 months. For example, if the windmill operates in colder regions, "the additional cost of such a system [de-icing] can be compensated by additional production within 2-3 years of operation." Source http://www.elforsk.se/Global/Vindforsk/Survey%20reports/12_13_report_icing.pdf
Of course, a wind turbine could be deiced by different means, like for example using hot water sprayed from a helicopter, but the savings on the initial building costs are translated to higher operational costs. For a one time de-icing "costs will be recovered within 48 hours compared to a reduced or no production."