WIND POWER The term windmill which typically refers to the conversion of wind energy into power for milling or pumping is sometimes used to describe a wind turbine 6 hour Areas are grouped into wind power classes that range from 1 to 7 A wind power class of 3 or above equivalent equivalent to a wind power density of 150 to 200 watts per square meter or a mean wind of 11 5 to 12 5 miles per 5 1 5 6 meters per second at a height of 33 feet 10 m above ground is suitable for utility scale wind power generation although some suitable sites may also be found in areas of classes 1 and 2 In the United States there are substantial wind resources in the Great Plains region and in some offshore locations
INTRODUCTION Wind power is an alternative energy source This means that the power of the wind can be used in place of other energy sources such as coal oil and nuclear reactions Fossil fuels such as oil coal and natural gas are available on Earth only in limited supplies and they will run out one day Fossil fuels also add carbon dioxide to the atmosphere when they are burned Scientists believe that this contributes to global warming Burning fossil fuels also adds other pollutants pollutants such as carbon monoxide and nitrogen dioxide to the atmosphere Unlike fossil fuels wind power is a renewable resource that cannot be depleted It also has the added benefit of being virtually pollution-free Challenges to the large-scale implementation of wind energy include siting requirements such as wind availability aesthetic and environmental concerns and land availability Public advocacy groups have raised concerns about the potential disruptions that wind farms may have on wildlife and overall aesthetics aesthetics For example wind generators have been blamed for injuring and killing birds However experts have shown that modern turbines have a small effect on bird populations 7
Chapter One WHAT IS WIND Wind is a familiar element of weather one that pretty much everyone has some experience with However many people don’t know how to really define wind or what causes it Simply put wind is the movement of air across Earth’s surface LOCAL WINDS All winds from gentle breezes to raging hurricanes are caused by differences in the temperature of the atmosphere by rotation of the Earth and by unequal heating of the continents and the oceans Simple examples of the effect of temperature on wind are land and sea breezes The sun heats land and water differently Over oceans and lakes most 8
WHAT IS WIND warm air of the heat energy is consumed in evaporation cool sea breeze evaporation or is absorbed by the water The air is not heated very much Land however day land warmer sea cooler absorbs only six tenths as much heat as water warm air does and evaporation is less Hence air over cool land breeze land tends to receive more heat than does air over water night land cooler sea warmer Heated air expands 2014 Encyclopædia Britannica Inc and becomes lighter This starts to occur over land soon after By day the land is warm and the sea sunrise Air over the cool The warm air rises and the cool air descends The breeze is off the sea does not heat sea At night the land is cool and the as rapidly and so it sea warm The breeze is off the land remains denser or heavier than the land air Its pressure near the Earth's surface is greater At length this extra pressure starts it flowing landward where it pushes the lighter land air up out of its way This movement is called a sea breeze
