Energy figures
I have followed with interest the debate, sometimes conducted with seemingly considerable authority, on your letters page regarding the merits or otherwise of different energy sources.
However, I do believe that when some energy sources are compared, like is often not truly compared with like when defining output.
Should an engineer from a coal powered generating station, for example, state that the output is 10MW then one can safely assume that for much of the time the output can be 10MW if required.
However, when a wind farm’s output is defined as 10MW, what does that really mean? If there is no wind, there is no output.
What wind strength is needed to produce the defined output? 10kts? 15kts? 20kts?
Not only that, but what percentage of the operating time is that wind strength going to be available? 10%, 20% or 30%? Who knows?
Well, the owners of the wind farm, for a start, as they will have carefully surveyed meteorological records for the area before investing.
May I therefore suggest that, when discussing the various merits of energy generation, wind-generated output is defined by three figures, namely maximum output, wind strength (in knots) required for that output and finally the percentage of the time on average that wind strength has been available in the recent past – say five years.
As a simple example, 10MW 20kt 30%. This takes up little space, all these figures are readily available and what a difference this would make to our perception of stated output.
No doubt a similar discipline should be applied to tidal-generated power.
W Hercus, Peerieskaill, 1 Croft Rise, Forres, Moray.
The Herald
10 October 2008
Tags: Wind power, Wind energy
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