The government is paying hundreds of millions of pounds to fund wind farms that are not viable, experts have told BBC Radio 4.
They say many farms in England, Wales and Scotland are underperforming because they are located in areas without enough wind.
Others are ready, but not connected to the National Grid so their electricity is not reaching homes, experts add.
But ministers insist wind energy is key to Britain’s future supply.
Experts told the Costing the Earth programme that government incentives are encouraging firms to site wind farms badly.
And in remote areas like northern Scotland, they say access to the National Grid is extremely limited and there is a backlog of farms waiting for connection.
The government is trying to reach an EU target of 20% of all electricity from renewable sources by 2020.
And under the Renewables Obligation Certificate Scheme it is offering financial incentives to companies to establish onshore or offshore wind farms in the UK.
But Michael Jefferson, chairman of the policies committee of the World Renewable Energy Network, said firms eager for the money often exaggerate the amount of wind energy a development will supply.
He also believes many wind farms are being badly sited in parts of England with relatively little wind like the Midlands and Home Counties.
“We should be putting our money where the wind is and that is quite often not where the development pressure is,” Mr Jefferson said.
Offshore sites receive most wind, but these are more expensive and difficult to develop, so onshore locations are preferred.
But Mr Jefferson said suitable onshore sites with a high enough load factor – the average amount of wind a particular spot gets in a year – were running out.
Experts recommend an average wind load factor of 30% for a turbine to operate efficiently.
In the windiest parts of the UK, it can be as high as 45%, but many developments in England achieve under 20%.
The lowest recorded by electricity watchdog Ofgem in 2006 were 3.3% and 7.6%
Engineering consultant Jim Oswald said many turbines were underperforming because wind speeds are too variable and unreliable.
“The volatility thing is a bit like driving your car and I say to you ‘OK here’s a green car it uses absolutely no fossil fuel but you can only use it when it’s windy,” Mr Oswald said.
“And if it’s medium wind you can drive it at a sensible speed, but if it’s very windy you’re going to be driving at 90mph through the town centre. Or some days you’ll have no wind at all and no car.”
Mr Oswald said this volatility could lead to major power failures in future if the system was not redesigned.
“It’s the power swings that worry us. Over a 20-hour period you can go from almost 100% wind output to 20%.”
Energy Minister Malcolm Wicks insisted that wind energy was an important part of Britain’s energy mix for the future.
He said the government was encouraging more offshore wind farms combined with tidal and marine power plants.
Wind power is Britain’s fastest growing source of renewable energy, but still meets less than 0.5% of our electricity needs.
30 August 2007
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