Environmental Problems, Their Causes, and Sustainability 1

AdvantagesModerate to highnet energyHigh efficiency(80%)Large untappedpotentialLow-cost electricityLong life spanNo CO 2emissionsduring operationin temperate areasMay provide floodcontrol below damProvides waterfor year-roundirrigation ofcroplandReservoir isuseful for fishingand recreationT rade-OffsLarge-Scale HydropowerDisadvantagesHigh constructioncostsHigh environmentalimpact from floodingland to form areservoirHigh CO 2 emissionsfrom biomass decayin shallow tropicalreservoirsFloods natural areasbehind damConverts land habitatto lake habitatDanger of collapseUproots peopleDecreases fishharvest below damDecreases flow ofnatural fertilizer (silt)to land below damthe wind turbines sold in the global marketplace.Denmark has banned coal and gets 90% of its electricityfrom wind. Nine of the world’s 10 leading windturbine manufacuring companies are in three countries—Denmark,Germany, and Spain—mostly becauseof strong and consistent government subsidiesand tax breaks.Wind power is also being developed rapidly in India(the world’s number-two market for wind energy)and to a lesser degree in China. By 2030, India coulduse wind to generate a fourth of its electricity.Much of the world’s potential wind power remainsuntapped. According to the 2003 Wind Force 12report, wind parks on only one-tenth of the earth’sland could produce twice the world’s projected demandfor electricity by 2020.ElectricalgeneratorPower cableGearboxFigure 18-22 Trade-offs: advantages and disadvantages ofusing large dams and reservoirs to produce electricity. Pick thesingle advantage and the single disadvantage that you thinkare the most important.Wind turbine18-5 PRODUCING ELECTRICITYFROM WINDWhat Is the Global Status of WindPower?A Star Is BornSince 1995 the use of wind turbines to produceelectricity has increased almost sevenfold.The greater heating of the earth at the equator than atthe poles and the earth’s rotation (Figure 6-8, p. 107)set up flows of air called wind. This indirect form of solarenergy can be captured by wind turbines (Figure18-23) and converted into electricity.Since 1990, wind power has been by far the world’sfastest growing source of energy, with its use increasingalmost sevenfold between 1995 and 2004.Europe is leading the world into the age of windenergy and out of the age of coal and other fossil fuels.About three-fourths of the world’s wind power is producedin Europe in inland and offshore wind farms.And European companies manufacture about 80% ofWind farmFigure 18-23 Solutions: wind turbines can be used to produceelectricity individually or in clusters, called wind farms orwind parks. Since 1990, wind power has been the world’sfastest growing source of energy. Our energy future may beblowing in the wind.396 CHAPTER 18 Energy Efficiency and Renewable Energy