Among renewable sources wind power systems have developed to prominent s- pliers of electrical energy. Since the 1980s they have seen an exponential increase, both in unit power ratings and overall capacity. While most of the systems are found on dry land, preferably in coastal regions, off-shore wind parks are expected to add signi?cantly to wind energy conversion in the future. The theory of modern wind turbines has not been established before the 20th century. Currently wind turbines with three blades and horizontal shaft prevail. The drivenelectricgeneratorsareoftheasynchronousorsynchronoustype,withorwi- out interposed gearbox. Modern systems are designed for variable speed operation which make power electronic devices play an important part in wind energy conv- sion. Manufacturing has reached the state of a high-tech industry. Countries prominent for the amount of installed wind turbine systems feeding into the grid are in Europe Denmark, Germany and Spain. Outside Europe it is the United States of America and India who stand out with large rates of increase. The market and the degree of contribution to the energy consumption in a country has been strongly in?uenced by National support schemes, such as guaranteed feed-in tariffs or tax credits. Due to the personal background of the author, the view is mainly directed on Europe, and many examples are taken from the German scene. However, the sit- tion in other continents, especially North America and Asia is also considered.
