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Environmental Science Chapter 18 Section 1
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Energy from sources that are constantly being formed. Examples: ◦ Solar ◦ Wind ◦ Water ◦ Earth’s heat
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Only a small fraction of the sun’s energy reaches the Earth. The energy is enough to power the wind, plant growth, and the water cycle. All forms of energy come either directly or indirectly from the sun.
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Passive Solar Heating ◦ Uses the sun’s energy to heat something directly. ◦ May use windows facing the direction where the sun strikes most directly in order to heat a building. ◦ Could potentially eliminate heating bills, but can definitely greatly reduce them.
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Active Solar Heating ◦ Energy from the sun is gathered by collectors and used to heat water or to heat a building. ◦ Collectors are usually mounted on a roof and capture the sun’s energy. ◦ Used primarily for water heating.
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Photovoltaic Cells ◦ Convert the sun’s energy into electricity. ◦ Solar cells have no moving parts. ◦ Solar cells produce a very small electrical current, so it cannot meet all of our energy needs. ◦ Solar energy production has doubled every four years since 1985. ◦ Provide energy for more than 1 million households in the developing world.
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Wind Farms ◦ Large arrays of wind turbines. ◦ In CA, supply electricity to 280,000 homes. ◦ Wind turbines take up little space, so can be placed on farms where the land can still be used for other purposes.
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An Underdeveloped Resource ◦ Scientists estimate that the windiest spots on Earth could generate more than ten times the energy used worldwide. ◦ One problem is transporting the electricity from rural areas where it is generated to urban centers where it is needed.
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Biomass fuel ◦ Plant material, manure, and any other organic matter that is used as an energy source. ◦ Renewable: wood and dung. ◦ Nonrenewable: fossil fuels.
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Methane ◦ A byproduct of bacteria decomposing organic waste. ◦ Gas that is used for heating and cooking. ◦ Some landfills in the U.S. use the produced methane to generate electricity. ◦ Britain opened the first dung-fired power station in 2002.
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Alcohol ◦ Ethanol can be made by fermenting fruit or agricultural waste. ◦ Corn is a major source of ethanol. ◦ Cars and trucks can run on gasohol (a blend of gasoline and ethanol).
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Hydroelectric energy ◦ Energy produced from moving water. ◦ Renewable resource that accounts for about 20% of the world’s electricity. ◦ Canada, U.S., Brazil, China, Russia, and Norway are the major producers (in decreasing order).
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The Benefits of Hydroelectric Energy ◦ Hydroelectric dams are expensive to build, but relatively inexpensive to operate. ◦ Do not release air pollutants that cause acid precipitation. ◦ Tend to last longer than fossil fuel-powered plants. ◦ Provide benefits such as flood control and water for drinking, agriculture, industry, and recreation.
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Disadvantages of Hydroelectric Energy ◦ A dam changes a river’s flow. ◦ A reservoir floods large areas of habitat above the dam and ecosystems downstream are disrupted by reduced water flow. ◦ Fertile sediment does not travel as far downriver. ◦ If a dam bursts, people may perish and property may be destroyed.
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Geothermal energy ◦ Deposits of water in the Earth’s crust are heated by energy within the Earth. ◦ The heat below Earth’s crust can be used to generate electricity. ◦ Geothermal power plants pump heated water or steam from rock formations and use the water or steam to power a turbine that generates electricity. ◦ The water is returned to the Earth’s crust where it can be heated and used again.
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Geothermal Heat Pumps: Energy for Homes ◦ More than 600,000 homes in the U.S. are heated and cooled using geothermal heat pumps. ◦ Temperature of the ground is nearly constant year- round. ◦ Heat pump is a loop of piping that circulates a fluid underground. In summer, the ground is cooler. In winter, the ground is warmer.
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