To harness the power of wind has always been one of the most important tasks for mankind. Confronted with global warming and a shortage on fossile energy resources, alternative and renewable energy systems become more and more crucial for the prosperous development of our modern society.
Within the mix of renewable energy systems, wind energy plays a major role. At the end of 2007 the amount of installed wind power within the European Union already exceeded 56 GW [Ass08c]. In the United States of America, the installed wind power reached 16.8 GW with a growth rate of 45 % compared to 2006 [Ass08a].
Today, Denmark is able to receive 20 % of its electricity needs from wind energy. Spain and Portugal had time periods in 2007 when they were able to meet the same level. Germany, with the highest number of installed wind power in a single country, is able to gain 7 % of its electricity from wind energy [Ass08b] with a growth rate of 28.7 % in 2007 [Bun08].
Despite these statistics the total number of renewable energy compared to fossile and nuclear energy systems remains small. Reasons for this are apart from other things the costs of renewable energy systems and the fluctuations of their availability. Latter is also a critical cost factor. Compensatory power plants need to stand by for the case of unavailability of a wind turbine. Availability is not only a matter of environmental conditions, like the presence of wind, but also a matter of facility reliability.