Wind farms are much less efficient than claimed, producing below 10% of capacity for more than a third of the time, according to a new report.
The analysis also suggested output was low during the times of highest demand.
The report, supported by conservation charity the John Muir Trust, concluded turbines "cannot be relied upon" to produce significant levels of power generation.
However, industry representatives said they had "no confidence" in the data.
The research, carried out by Stuart Young Consulting, analysed electricity generated from UK wind farms between November 2008 to December 2010
Statements made by the wind industry and government agencies commonly assert that wind turbines will generate on average 30% of their rated capacity over a year, it said.
But the research found wind generation was below 20% of capacity more than half the time and below 10% of capacity over one third of the time.
'Different manner'
It also challenged industry claims that periods of widespread low wind were "infrequent".
The average frequency and duration of a "low wind event" was once every 6.38 days for 4.93 hours, it suggested.
The report noted: "Very low wind events are not confined to periods of high pressure in winter.
"They can occur at any time of the year."
During each of the four highest peak demands of 2010, wind output reached just 4.72%, 5.51%, 2.59% and 2.51% of capacity, according to the analysis.
It concluded wind behaves in a "quite different manner" from that suggested by average output figures or wind speed records.
When will this utter waste of money cease and common sense prevail?
Why is so much money wasted on such an inefficient technology?
Can the world afford this wastage when so many people are suffering due to the global recession?
Is this one of the reasons why utility bills are soaring due to excessive green taxes?
What will this utter waste mean for our poor grandchildren?
More here: http://www.bbc.co.uk/news/uk-scotland-12985410
