It is often said that wind power covers c. 20% of Danish electricity consumption. It is more correct to say that the production of power by Danish wind turbines corresponds to about 20% of electricity demand. A considerable part of the wind energy produced is exported to neighboring countries and thus does not cover any part of Danish electricity consumption.
Now, the question is how can one know that it is wind energy and not coal-electricity which is exported? In the present report, Danish electricity production in the years 2005 and 2006 is analyzed in a way not used previously. It is shown that in many cases there is a strong relationship over time between wind power production and net exports. It is therefore concluded that it is mainly wind power which is exported. The wind energy used in Denmark is thus calculated as wind power production minus net exports when this is positive. (See section 3 of the report for other situations.)
The following figure shows an example. The solid (green) curve gives wind power production in West Denmark (Jutland/Funen) over a 60-hour period in the middle of December 2005. [Below it is the same graph for the whole month.] The dashed (red) curve gives net exports. The claim that 20% of Danish electricity consumption is covered by wind power means that one takes all the under the green curve and says that this is the wind energy used in Denmark. But for the method used in the present report the area under the dashed curve is subtracted, because it is exported. In this way, the wind power used in Denmark becomes less and the level of coverage falls.
One could naturally believe that the correspondence of the two curves in the figure is coincidental. However, this is not the case. In the report, the extent to which the production of wind power and net exports “swing in step” month by month is calculated. In West Denmark, this is predominantly the case. In East Denmark, where the [non-wind] power stations also produce for export, the tendency is less pronounced. To get a general assessment of the amount of wind power used in Denmark, it is therefore necessary to use a more sensitive estimate fo the relationship, as explained in section 3. … For the whole country, the level of coverage in 2005 was 13.6% (not 18.7% as stated by the wind turbine industry), and in 2006 it was 10.3% (not 17%).
Thus, the perception that Denmark gets c. 20% of its electricity consumption covered by wind turbines is incorrect.
Download original document: “Analysis of Wind Power in the Danish Electricity Supply in 2005 and 2006”
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