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Tuesday, June 01, 2010

Wind Variability in Germany

By adding more data to the post on wind dispersion, we can observe how dispersion in wind speeds has a universal character. I picked up the previous data set from several years worth of output from Ontario. This new set hails from northwest Germany and this site (thanks to globi for the link). The data consists of wind power collected at 15 minute intervals.

Note that the same entropic dispersion holds as for Ontario (see graph to the right). Both curves display the same damped exponential probability distribution function for frequency of wind power (derived from wind speed). We also see the same qualitative cut-out above a certain power or wind energy level. As I said previously, we don't gain much by drawing from these higher power levels as they occur more sporadically than the nominally rated wind speeds at the upper reaches of the curve.

The following figure gives an explanation for the cutout above the "max" wind speed. Globi also provided this PDF from Vestas, a maker of wind turbines. The end of the document has the complete spec.
Power regulation : pitch regulated with variable speed
Operating data
Rated power : 3,000 kW Cut-in wind speed : 3 m/s
Rated wind speed : 12 m/s
Cut-out wind speed : 25 m/s
Too many people get the idea that the sporadic nature of wind confronts us with some kind of "problem". We will have to get used to a different way of thinking about wind. The entropic dispersion of wind acts much like a variation of the Carnot cycle. In the Carnot cycle of engine efficiency, we have to live with a maximum level of energy conversion based on temperature differences of the input and output reservoirs. With wind, the earth's environment and atmosphere provides the temperature differences which leads directly to the variability over time.

Which leads to the fact that WITH WIND POWER, WE CAN ACHIEVE VERY HIGH USAGE EFFICIENCY GIVEN THE ENTROPIC CHARACTERISTICS OF THE WIND. I put this in upper case because it amounts to a law of nature. We need to talk about efficiencies within the constraints of the physical laws just as with the Carnot cycle. We will observe intermittency as a result of entropic dispersion and we have to get used to it. We should not call it a fundamental "problem", as we cannot change the characteristics of entropy (apart from adding energy, and that just moves us back to square one).

Other people would suggest that the fundamental problem with farming derives from the intermittent nature of the rain. With farming, we adapt -- likewise with wind energy. Instead of a problem, we need to call it an opportunity.

As a blast from the past check out my expose of the forged video editing by the George Bush marketing team against John Kerry. Wind energy advocates will have to watch out for these tactics as the right-wingers will project and frame any way they can to make wind look like a wimpy exercise designed by the elite for the elite.


Professor Blogger jstults said...

With farming, we adapt -- likewise with wind energy. Instead of a problem, we need to call it an opportunity.
MacArthur said it like this: There is no security on this earth, there is only opportunity.

7:34 PM  
Professor Blogger WHT said...

And "Americans never quit"

The security quote is also very apt considering how often we get spun up by the fear of terrorism, instead of focussing on holding our infrastructure together.

8:10 PM  
Professor Blogger globi said...

Oh, I've just noticed that you've analyzed the German wind data as well. It is really good to know that it corresponds so well with the Canadian data. Thank you for your efforts.

By the way, meanwhile you can also get the German photovoltaic power data here (also in 15 minute intervals):
But since the sun inclination depends on the hour of the day and the day of the year the PV power probably distribution will differ from the (more random) wind power probability distribution. Unless if one would just analyze/compare certain hours of the day within certain months? (Also, PV has been added much faster than wind power.)

2:39 PM  

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