The biggest problem with industrial wind power stations is that the power they generate is intermittent, unpredictable and unreliable.

Turbines will not work if the wind is not  strong enough, while if it is too strong the generators have to be locked down to avoid damage. In a speech in the House of Lords on 7 May, Lord Reay claimed an idleness rate for turbines of between 55 and 110 days a year.

There is now data available which shows that the frequency of total wind collapse across the UK is higher than generally understood and that these low wind situations are often across the whole of Europe at the same time.

For example, between October 2008 and February 2009 there were 58 days when turbine output across the whole of the UK would have dropped below 5% of the rated capacity and and on 24 of these days, output would have remained below 5% all day.

What this means is that wind power cannot be relied on at times of peak demand and that they require to be totally backed-up (a fact still contested by some!).   

Read more at When the wind stops

And take a look at what Scottish Power, one of the major supporters of wind energy, has to say about back up - click here.

As ever, the wind industry is working hard to play down the intermittency problem and we expect to see a series of reports commissioned by them. We also expect a series of robust responses from more objective sources.

Power Generated

The power generated by an on-shore wind turbine is likely to be between 25% and 30% of its rated capacity. Assuming the former figure, a turbine rated at 2MW (Megawatts) on average throughout the year will generate only 500KW (Kilowatts). To put this in perspective, this is equivalent to the maximum power output of about seven family saloon cars!

Developers often try to exaggerate the power output of wind turbines by quoting how many local homes will be supplied.

Take a look at 'Homes supplied by a windfarm'or read "The Wind Farm Scam" for an up to the minute review of this topic.

CO2 Savings

In previous years, developers exaggerated the CO2 savings attributable to wind power stations by a factor of 2 until they were challenged. Much to their embarrassment they now have to use a much lower figure and this figure will decline again in 2010 as more efficient conventional power stations come on line.

Read more at 'Calculating CO2 emissions and savings' or read "The Wind Farm Scam" for an up to the minute review of this topic.

Economics

If we assume that the developers propose three 2.3 MW turbines, they can expect to generate an income of approximately £35 million over the 25 year life of the wind power station. From this they will of course have to deduct expenses such as the cost of the turbines, civil works, loan interest, insurance, maintenance etc, however, the outcome for them is like to be an accumulated profit in the region of £9 million over this period.

Technical Aspects

For more information click here or read "The Wind Farm Scam".