Winds in Complex Terrain

Abstract

More and more onshore wind turbines are built away from flat regions near the coasts in complex (i.e. hilly or mountainous) terrain. The most favourite sites in complex terrain are at elevated positions such as hilltops. But sites in complex terrain also bear risks. In Japan, e.g. 1516 wind turbine accidents have been recorded between year 2004 and 2012, and 84% of them were for turbines in complex terrains. The longest downtime was associated with damage to main shafts or bearings with an average downtime of 5.7 months. Careful micrositing in complex terrains can prevent these accidents from happening (Watanabe and Uchida in Wind Eng 39:349–368, 2015). Therefore, this chapter introduces a few of the main flow features which influence wind energy yields in complex terrain.