Winds of Change

Before we go any further down the approval route for additional wind farms I believe it is necessary to consider the detailed findings of the most recent reports on the subject by the Renewable Energy Foundation.  

A fundamental problem with generating energy from the wind is that power is a cubic function of wind speed.

This makes power very, very sensitive to wind speed.

Halving the wind speed from 10 m/sec to 5m/sec reduces the power from 73% of rated output to 6%. A 12 fold decrease.

Distributed wind is smoother than local wind but output is still highly volatile and uncontrolled.

Aggregated UK output for January 2006 shows 70% rise and fall in 24 hours with a total change of 97% within the month.

This means that alternative means of generation have to be available to provide basically the same amount of power at a few minutes notice!

In reality the standby generating equipment is likely to be kept running all the time.  

Statistically, minimum wind occurs on colder days.  

Too much wind capacity causes problems with the control and balancing of the overall generating system.

Balancing plant will operate less reliably as a consequence of cycling.  

If one is sceptical the primary reason for the rush for further wind stations could be attributed to the significant grants which are available to constructors/operators.  

The media carry a lot of responsibility for the inaccurate way wind energy is perceived by the general public.

When a new wind farm is announced it is usually accompanied by a statement that it will provide sufficient energy for a town of x thousand people. What it always fails to mention is that it can only do this when the wind is blowing at the right speed and at the right time.  

D Deacon F I Mech E

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