10. Moderate to high net energy High efficiency (80%) Large untapped potential Low-cost electricity Long life span No CO 2 emissions during operation May provide flood control below dam Provides water for year-round irrigation of crop land Reservoir is useful for fishing and recreation High construction costs High environmental impact from flooding land to form a reservoir High CO 2 emissions from biomass decay in shallow tropical reservoirs Floods natural areas behind dam Converts land habitat to lake habitat Danger of collapse Uproots people Decreases fish harvest below dam Decreases flow of natural fertilizer (silt) to land below dam Advantages Disadvantages Trade-Offs Large-Scale Hydropower
12. Moderate to high net energy High efficiency Moderate capital cost Low electricity cost (and falling) Very low environmental impact No CO 2 emissions Quick construction Easily expanded Land below turbines can be used to grow crops or graze livestock Steady winds needed Backup systems needed when winds are low High land use for wind farm Visual pollution Noise when located near populated areas May interfere in flights of migratory birds and kill birds of prey Advantages Disadvantages Trade-Offs Wind Power
13. Producing Energy from Biomass Biomass and biofuels Biomass plantations Crop residues Animal manure Biogas Ethanol Methanol
16. Can be produced from plentiful water Low environmental impact Renewable if produced From renewable energy resources No CO 2 emissions if produced from water Good substitute for oil Competitive price if environmental and social costs are included in cost comparisons Easier to store than electricity Safer than gasoline and natural gas Nontoxic High efficiency (65-95%) in fuel cells Not found in nature Energy is needed to produce fuel Negative net energy CO 2 emissions if produced from carbon-containing compounds Nonrenewable if generated by fossil fuels or nuclear power High costs (but expected to come down) Will take 25 to 50 years to phase in Short driving range for current fuel cell cars No distribution system in place Excessive H 2 leaks may deplete ozone Advantages Disadvantages Trade-Offs Hydrogen
17. Utilization Electric utility Transportation Commercial/Residential Industrial Storage Gas and solids Transport Vehicles and pipeline Photo-conversion Electrolysis Reforming Hydrogen Production Electricity Generation Primary Energy Sources Sunlight Fossil fuels Biomass Wind
18. Entering the Age of Decentralized Micropower Decentralized power systems Micropower systems
19. Bioenergy Power plants Wind farm Small solar cell power plants Fuel cells Solar cell rooftop systems Commercial Microturbines Industrial Transmission and distribution system Residential Small wind turbine Rooftop solar cell arrays
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