Wind energy

Energy from the wind is not new. Two hundred years ago windmills were a common feature of the European landscape; for example, in 1800 there were over 10 000 working windmills in Britain. During the past few years they have again become familiar on the skyline especially in countries in Western Europe (for instance, Denmark, Germany, UK and Spain) and in western North America. Slim, tall, sleek objects silhouetted against the sky, they do not have the rustic elegance of the old windmills, but they are much more efficient. A typical wind energy generator installed during the last decade will have three-bladed propeller about 50 m in diameter and a rate of power generation in a wind speed of 12 m s-1 (43 km h-1, 27 mph or Beaufort Force 6), of about 700 kW. On a site with an average wind speed of about 7.5 m s_1 (an average value for exposed places in many western regions of Europe) it will generate an average power of about 250 kW. The generators are often sited close to each other in wind farms that may include several dozen such devices. The size of the largest generators has grown steadily, roughly doubling every five years, the largest now being 5 MW to 6 MW units with rotor diameters of around 120 metres.

From the point of view of the electricity generating companies the difficulty with the generation of electrical power from wind is that it is intermittent. There are substantial periods with no generation at all. The generating companies can cope with this in the context of a national electricity grid that pools electrical power from different sources providing that the proportion from intermittent sources is not too large.46 Some public concern about wind farms

Wind turbines.

arises because of loss of visual amenity. Offshore sites, that are not seen to possess the same amenity disadvantage and that generally provide stronger and steadier winds, are being increasingly used for large wind farms.

Rapid growth has occurred in many countries in the installation of wind generators for electricity generation over the past decade - a growth that continues unabated. Over 100 GW peak operating capacity has now (2008) been installed worldwide providing about 1% of global electricity supply. With this large growth, economies of scale have brought down the cost of the electricity generated so that it is competitive with the cost of electricity from fossil fuels. Because the power generated from the wind depends on the cube of the wind speed (a wind speed of 12.5 m s-1 is twice as effective as one of 10 m s-1) it makes sense to build wind farms on the windiest sites available. Some of these are to be found in Western Europe where rapid growth in wind generation is occurring. In Denmark, for instance, nearly 20% of electricity is now generated by wind - increasingly from wind farms being built offshore. Substantial offshore wind energy generation is also planned for the UK. Developing countries are also making increased use of wind energy. For instance, India with 8 GW

Renewable Energy Eco Friendly

Renewable Energy Eco Friendly

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable.

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