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Wind power in Finland

Is it windy in the winter?

It is commonly claimed that wind energy is not available during winter-zero temperatures, when heating energy consumption needs are greatest. This claim is incorrect.

Finnish wind power production is actually at its greatest during the cold winter months, when energy consumption is also highest. The common misconception about windless sub-zero days is not actually true, especially at the 100-140 meter nacelle height of modern wind turbines. Cold air has a higher air density and so produces more energy at the same wind speed as warm air.

Wind energy production varies by season. In offshore, coastal and highland areas the winter months are noticeably windier than the summer months. Wind power production is highest in the winter months November-March, during which 60% of annual wind energy is produced.

The proportion of extremely cold winter days is generally quite small. From the figures that follow it can be seen that wind turbines have good electricity production even if very cold temperatures are experienced in neighboring villages and towns.

The following figure shows the offshore wind power monthly percentages of annual production and seasonal variations in the years 1999-2003, overlain with electricity consumption measurements from 2003. Electricity consumption and production matched each other well.

The figure below shows the estimated production of a 1500 kW wind turbine on the top of Pyhätunturi fell calculated using wind speed measurements from an ice-free anemometer (% rated power per 3hrs, vertical axis on the left), at different temperatures measured at Sodankylä weather station. Temperature readings are grouped into 5ºC classes. The horizontal axis shows the temperature classes and their lower limits. The continuous black line and the right vertical axis show the temperature class percentage of the total annual temperature distribution. In summary, wind turbine power production is better in colder conditions than in warmer conditions.

The figure below shows the estimated production of a 1500 kW wind turbine at Mustasaari / Valassaaret, calculated using wind speed measurements from an unheated anemometer (% rated power per 3hrs, vertical axis on the left), at different temperatures measured at Kauhava weather station. Temperature readings are grouped into 5ºC classes. The horizontal axis shows the temperature classes and their lower limits. The continuous black line and the right vertical axis show the temperature class percentage of the total annual temperature distribution.

Wind energy production during electricity consumption peaks

According to Finnish Energy Industries’ monthly energy statistics, during the national consumption peak on 28.1.2010, wind power produced 80MW, which is 55% of the rated power (average efficiency is 23%). During the December 2009 consumption peak, wind power produced 40MW.

Sources:

B. Tammelin ja R. Hyvönen, 2002. Tuottavatko tuulivoimalat pakkasella? Tuulensilmä 1/2002