chapter 11 section 2: renewable sources of energy
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Chapter 11 Section 2: Renewable sources of energy. Key Concepts: What forms of energy does the sun provide? What are some renewable sources of energy? Key terms: Solar energy, hydroelectric power, biomass fuel, gasohol, geothermal energy. Renewable sources. Solar Water Wind Biomass - PowerPoint PPT PresentationTRANSCRIPT
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Chapter 11 Section 2: Renewable sources of energy• Key Concepts:• What forms of energy does the sun
provide?• What are some renewable sources of
energy?• Key terms:• Solar energy, hydroelectric power, biomass
fuel, gasohol, geothermal energy
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Renewable sources
• Solar• Water• Wind• Biomass• Geothermal• Hydrogen
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Sun’s energy• Solar energy – energy from the sun• The sun constantly gives off energy in the forms of heat and light• It’s hard to use the sun’s energy because:• Only useful when it’s shining• Widespread, so hard to harness a lot of it within a small area
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Solar stuff• Solar Power Plants – use giant mirrors to heat
water to steam• Solar cells – like a battery. Light hits it and
electric current is produced. Takes a lot of them.• Passive Solar Heating – converts sunlight into
thermal energy• Active Solar Heating – captures energy on a
dark metal surface of a solar collector, converts it to thermal energy
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Hydroelectric power• Hydroelectric power is electricity
produced by flowing water• Flowing water can move turbines, just
like steam or wind, and create an electric current
• Hydroelectric is the most widely used form of renewable energy• Requires a dam, which can affect
ecosystems• Inexpensive and no air pollution, once
dam is built
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Capturing Wind• Wind energy is an indirect form of solar energy• Wind is caused by uneven heating of the earth by the sun• Wind can be used to turn a turbine• Does not cause air pollution, but can be noisy and ineffective. AND
the metal to make the turbine has to be mined and then processed into steel. Very few people mention that the MAKING of “green energy” materials are very un-green.
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Biomass fuels• Biomass fuels are made from living things• The best example is wood• Leaves, food wastes, manure• Can be burned or converted to other fuels• For example, corn, sugar cane, and other crops can be used to make alcohol• Adding alcohol to gasoline makes gasohol, which can be used as car fuel
• Bacteria produce methane when they decompose biomass, and the methane can also be captured and used as fuel• Biodiesel fuel – oil produced by some crops• Drawbacks: takes time, expensive
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Tapping Earth’s Energy
• Intense heat from Earth’s interior is called geothermal energy• In CERTAIN (not everywhere!) areas, like Iceland and New Zealand,
magma heats underground water to boiling. Hot water and steam can be valuable energy sources. • Disadvantages: doesn’t work everywhere, requires deep drilling
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Promise of hydrogen power
• Pure hydrogen can be obtained by passing electricity through water• Takes more energy to obtain the hydrogen than it produces