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Objectives
Analyze the need for alternative energy sources.
Compare the advantages and disadvantages of various alternate energy sources
Describe alternate methods for generating electricity.
Renewable resource
Can be replaced almost as quickly as it is usedExample: Because only about one billionth of
the Sun’s energy falls on Earth, and because the Sun is expected to continue producing energy for several billion years, solar energy cannot be used up
Solar Energy
Converted into electricity by a photovoltaic cell, or solar cell
A solar cell contains one layer of electron-rich semiconductor material and one layer that is electron-poor
Solar cells
Energy produced by solar cells is more expensive than energy produced with fossil fuels
Energy from solar cells must be stored in batteries when the sun is not shining
Hydroelectricity
Produced by moving waterIt is about twice as efficient as fossil fuels
or nuclear power
Tidal energy
Uses moving waterAs the tide comes in, the moving water
spins a turbine that generates electricityThe water is then trapped behind a damAt low tide the water behind the dam flows
back out to the ocean, spinning the turbines and generating electric power
Windmills
Can be used to generate electricity Wind spins a propeller that is connected to
an electric generatorOnly useful when the wind blows
consistently
Geothermal energy
Thermal energy contained in hot magmaLimited to areas where magma is close to
the surface
Alternative fuels
Biomass = renewable organic matterSuch as wood,
sugarcane fibers, rice hulls, and animal manure
Burned in the presence of oxygen to convert the stored chemical energy to thermal energy