Wind Power, Introduction

Windmills have existed for at least 3,000 years, mainly for grinding grain or pumping water. The use of windmills to generate electricity is a twentieth-century development and in the early 1970s started the development toward modern wind turbine technology. Wind power has increased significantly during the last decade and there are currently many power systems, or subsystems, with comparatively large amounts of wind power. In 2009, Spain covered 14% [1] of their electric energy demand with wind power. The corresponding figures were for Portugal 15% [2], Ireland 11% [3], and Western Denmark 25% [4].

This means that wind power has developed from a marginal source to a source with important impact on national power system balances. But in many countries, wind power still only contributes to a small part of the electric supply. The total installed capacity at the end of 2009 reached 158,000 MW including 37,000 MW installed during 2009. A third of these additions were made in China, which...