Wind Power Variability
Early in his career, Mark Diesendorf was a principal research scientist with CSIRO where he was involved in early research on integrating wind power into electricity grids. This issue is discussed in some detail in Greenhouse Solutions with Sustainable Energy.
Diesendorf explains that large-scale wind power is not "intermittent", because it does not start up or switch off instantaneously. In practice, the variations in thousands of wind turbines, spread out over several different sites and wind regimes, are smoothed. As the distance between sites increases, the correlation between wind speeds measured at those sites, decreases. This has been confirmed recently by studies conducted by Graham Sinden from Oxford University:
analysed over 30 years of hourly wind speed data from 66 sites spread out over the United Kingdom. He found that the correlation coefficient of wind power fell from 0.6 at 200 km to 0.25 at 600 km separation (a perfect correlation would have a coefficient equal to 1.0.) There were no hours in the data set where wind speed was below the cut-in wind speed of a modern wind turbine throughout the United Kingdom, and low wind speed events affecting more than 90 per cent of the United Kingdom had an average recurrent rate of only one hour per year.
Diesendorf goes on to say that every conventional power station breaks down unexpectedly from time to time, causing an immediate loss of all its power. That is true intermittency, according to Diesendorf, and it is a particular type of variability that switches between full power and no power. Once a conventional power station has broken down, it may be offline for weeks, much longer than windless periods.
Read more about this topic: Greenhouse Solutions With Sustainable Energy
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