Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Alternative Sources – Ch. 20 & 21

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Nuclear energy Nuclear energy = the energy that holds together protons and neutrons within the nucleus of an atom nuclear fission = the splitting apart of atomic nuclei

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Nuclear Power Plant 101 in U.S101 in U.S.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 436 online436 online Under ConstructionUnder Construction CTCT NYNY

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Coal versus nuclear power

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Radioactive WasteHalf-Life Iodine days Strontium 9028 years Cesium years Uranium million years Waste stored onsite in pools – expected to be at capacity in 2015

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings NIMBY – not in my backyard

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Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Yucca Mountain, Nevada NRDC Testimony on Fukushima

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Breeder Reactors

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fusion Research Nuclear fusion = the process that drives our Sun’s vast output of energy -The force behind hydrogen (thermonuclear) bombs -Involves forcing together the small nuclei of lightweight elements under extremely high temperature and pressure

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Renewable Energy Around the World

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Biomass Biomass sources include a variety of materials Biopower = produced when biomass sources are burned in power plants, generating heat and electricity Biofuels = biomass sources converted into fuels to power automobiles

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Biomass sources are widely used More than 1 billion people use wood from trees as their principal energy source In developing nations, families gather fuelwood for heating, cooking, and lighting Fuelwood, charcoal, and manure account for 35% of energy use Fuelwood and other biomass sources constitute 80% of all renewable energy used worldwide

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Biomass can be overharvested Biomass is only renewable when it is not overharvested -With rapid deforestation, soil erosion, and forest failures to regrow, biomass is not replenished As developing nations industrialize, fossil fuels are replacing traditional energy sources Biomass use is growing more slowly than overall energy use

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Biofuels can power automobiles Ethanol = produces as a biofuel by fermenting carbohydrate-rich crops -Ethanol is widely added to U.S. gasoline to reduce emissions -Any vehicle will run well on a 10% ethanol mix

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Biodiesel is produced from vegetable oil U.S. biodiesel producers use soybean oil -Animal fats, used grease, and cooking oil can also be used -Vehicles can run on 100% biodiesel, but the engine needs to be modified -Biodiesel cuts down on emissions; its fuel economy is almost as good and costs slightly more than gasoline

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Biomass Energy Advantages Carbon neutral (IF not overharvested) Supports rural communities Reduced emissions: SO2, mercury Reduced dependence on fossil fuels Disadvantages Indoor air pollution if not vented IF crops used – competes with food production, fertilizers, pesticides, high energy input Alternative Sources of Biofuel

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Hydroelectric power Hydroelectric power = uses the kinetic energy of moving water to turn turbines and generate electricity Storage technique = impoundments harness energy by storing water in reservoirs behind dams -Water passing through the dam turns turbines Run-of-river approaches generates energy without greatly disrupting the flow of river water

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings A typical dam

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings A run-of-river system

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Hydropower Advantages Renewable No emissions High Efficiency EROI = 10:1 Disadvantages People displaced Habitat destruction upstream and downstream Diadromous fish blocked from migrating to spawn Natural flooding cycles disturbed Thermal pollution Most large rivers already dammed

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Hydropower may not expand much more China’s Three Gorges Dam is the world’s largest dam Most of the world’s large rivers have already been dammed People have grown aware of the ecological impact of dams Developing nations will probably increase hydropower if they have rivers

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Solar energy Passive solar energy = the most common way to harness solar energy Buildings are designed to maximize direct absorption of sunlight in winter and keep cool in summer Active solar energy collection = uses technology to focus, move, or store solar energy

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Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Active – Solar Water Heating

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Ecohomeduluth.com Passive – space heating

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Location is a drawback Not all regions are sunny enough to provide enough power, with current technology -Daily and seasonal variation also poses problems

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings U.S. wind-generating capacity Wind's capacity to generate power varies according to wind speed