In order to reduce the effect of random weather conditions, the energy generated by wind turbines is normalised according to a procedure as laid down in the new EU Directive Renewable Energy. The normalised production in 2012 is calculated as the capacity in 2012 multiplied by the average production per unit of capacity over the past five years. Electricity generated from hydropower is also normalised.
Despite the capacity expansion, the actual amount of electricity generated by wind turbines fell from 5,100 million kWh in 2011 to 4,965 million kWh in 2012. This reduction is caused by lack of wind last year. The normalisation procedure corrects for this effect and the percentage rise of the normalised production is approximately equal to the percentage capacity expansion.