Anti windfarm campaigners in Sutherland say they are not surprised by new research which has found that many costly onshore turbines are wearing out prematurely.
Data collated in the UK and Denmark suggests they last between 10 and 15 years – and not the “20 to 25 years” projected by the industry.
Energy economist Professor Gordon Hughes of the University of Edinburgh found that after a decade’s operation, the contribution of the average UK windfarm to meeting electricity demand drops by a third, probably due to wear and tear.
The Renewable Energy Foundation (REF) charity, which commissioned the review, says it applied “rigorous statistical analysis to years of actual windfarm performance data” to gauge the efficiency of the turbines.
REF says that rate of decline means it is “rarely economic to operate windfarms for more than 12 to 15 years,” after which time they need replacing.
Its director, John Constable, warned that the revelation had “profound consequences for investors and government alike”.
He said: “This study confirms suspicions that decades of generous subsidies to the wind industry have failed to encourage the innovation needed to make the sector competitive.
“Bluntly, wind turbines cost too much and wear out far too quickly to offer the developing world a realistic alternative to coal.”
Professor Hughes, who has advised the World Bank on energy and environmental policy, said the findings raised important implications for policy towards wind generation.
He believes people will still invest in the technology because of “generous subsidies to the industry”. But he suggested that the current structure of contracts offered to wind generators should be modified “since few wind farms will operate for more than 12 to 15 years”.
Golspie-based Allan Tubb of Landscape, a pressure group which has opposed Sutherland’s windfarms, said: “Wind turbines have never been able to match up to the promises. It is a very expensive way to generate unreliable electricity.
“Major windfarms in Sutherland are built on deep peat. A Scottish Government report has shown that disrupting peat bogs releases carbon into the environment and predicts windfarms built on deep peat require more than 25 years to pay back these carbon emissions by the generation of electricity.”
He added: “The industry regulator Ofgem relies entirely on information provided by the operator of a wind turbine without its own independent access to metering and without the ability to monitor performance.”
Fellow objector Peter Daniels, of Loth, said: “This latest report comes as no surprise. I’m all for green energy, but they’ve got it wrong with windfarms.
“They’re an eyesore, they release CO2 when built on peatland and now they’re costing customers millions of pounds a year for often standing idle.
“Mr Salmond will get his come-uppance pretty soon, I would say.”
The new data was instantly questioned by wind farm operators.
Jenny Hogan, of the trade body Scottish Renewables, said: “Our oldest commercial windfarms in Scotland are around 16 years old and none of them have been decommissioned or repowered.
“Technology is advancing all the time and windfarms are no different.
“Everyone who drives a car understands parts will need to be replaced and there will also come a time when you want to trade in for a better, more suitable model. It’s not much different for windfarm operators.”
The Scottish Government declined to comment on the new data.
In a statement, it said: “Scotland’s clean, green energy resources are delivering thousands of high quality jobs and hundreds of thousands of pounds of investment to communities across Scotland.
“Wind power is already making a meaningful contribution to Scotland’s power supplies, with onshore wind meeting around 18 per cent of forecast Scottish energy demand for 2011.”