Wind power
The use of wind energy has become increasingly important in recent years. Since the 'modern' use of wind power for electricity supply started in Denmark and the United States at the beginning of the 1980s, installed capacity worldwide has risen to more than 39 GW at the end of 2003, with Germany and Spain also being responsible for growth in the last decade to a significant degree. At the beginning of 2004 around 77% of the global capacity was installed in these four countries. Use of wind power was characterised by significant growth during both these decades. The worldwide installed capacity of wind energy converters, commonly referred to as wind turbines, doubled around every 32 months in the two decades from 1983 to 2003 and grew annually by around 30% on average,1 both in the first and second decades. This rate of expansion was achieved by a rise in the annual growth rate of new instal lations averaging 15% between 1983 and 1993, and further increasing to 33% between 1993 and 2003. At the same time there was a constant increase in the rated capacity of individual wind turbines. In Germany the larger proportion of newly installed capacity is at present provided by powerful wind turbines with rated capacities over 1,000 kW. The megawatt class wind turbine with rated capacities of 1-2 MW continually gained ground after its commercial introduction at the beginning of 1995, attaining a share of the rated power of more than a third of new installations by the start of 1998, and had apparently passed its zenith in Germany in 2002 at more than 70%, 'ousted' by even larger turbines. A long side turbine capacity the hub height (HH) has also increased from around 30 m at the beginning of the 1990s to an average of almost 80 m in 2002, which helps increase yields due to greater wind speeds. With technical development, the costs of wind energy have fallen sharply. When the wind industry started to develop in California in the early 1980s, electricity from wind energy cost 38 USct (cents) per kilowatt hour. Since then, costs at the best sites have fallen to USct or less, and some long-term supply contracts have been signed for USct per kilowatt hour. If these figures and the global installed wind turbine capacity are applied, cost reductions of 24% are achieved for a doubling of the output of all installed turbines. The development of wind energy yield therefore follows a very dynamic course, both from a technical and an economic angle.
Wind power, Page 1 of 2
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