Hydroelectric Power
Advantages:
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Concentrated potential energy (versus light)
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Relatively inexpensive to operate a dam
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Conversion of the forces of water to electric energy can be up to 90 % efficient
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No chemical or waste heat pollution
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Reservoirs can be used to breed fish
Disadvantages:
-Dams dramatically change natural flow of a river
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Backs up one side, creates a reservoir which destroys preexisting habitats
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Migration of spawning fish is disrupted
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Other side is reduced to relative trickle which changes the countryside and wilderness recreation
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Does not receive nutrient rich silt
-Reservoir-induced seismicity (earthquakes where there were none before)
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The larger and faster a reservoir is filled the greater the intensity of the seismic activity
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Reservoirs increase surface area of water
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increase evaporation
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serious water loss and increased salinity in the remaining water
-Waterborne diseases – schistosomiasis – tropical disease caused by a parasitic worm who inhabit the reservoir
-Costly to build, limited lifespan
-Displaces people and cultures
Geothermal Power
Advantages:
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Incredible potential (1% heat in Earth’s crust = 500 x Energy in all of Earth’s oil and natural gases)
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once the initial investment is paid for, and energy is cheap
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Geothermal Heat Pumps are the most efficient heating system available according to the EPA – lowest carbon emissions
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Inexpensive, reliable electricity
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Takes up very small area of land (compared to coal/nuclear/other renewable) suited for integrated industrial use - producing electricity, process steam,and heat for a variety of industries
Disadvantages:
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initial expense, can cost thousands of dollars to dig out the land and lay the pipes
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water used to generate electricity is not efficient enough
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in the Geysers geothermal field ½ of the water was depleted after only 5% of the heat was tapped
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some geothermal sites emit enough hydrogen sulfide (H2S) to require mitigation to meet air quality standards
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pollution control is effective, but adds to the energy cost
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surrounding land may subside as water from hot springs is removed
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uncertainty about how long each geothermal well will last
Biomass Energy
Advantages:
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Reduces dependence on fossil fuels
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Makes use of waste reduction of waste disposal problem
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Mesquite Lake Resource Recovery Project in S. California burns cow manure too salty to be used as fertilizer and generates energy for thousands of people
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Biomass combustion produces significantly less sulfur and ash than bituminous coal
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levels of carbon released can be absorbed by regenerating (planting trees) biomass
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largest biomass power plant in North America uses sugar cane fiber and recycled urban wood to generate power for its milling and refining operations
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excess energy supplies renewable electricity for nearly 60,000 homes
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reduces dependence on oil by more than one million barrels per year
Disadvantages:
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requires land/water to produce biomass
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agricultural land needs both of these as well, so a shift to biomass production might raise food prices
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some scientists propose the use of oils from desert shrubs (wouldn’t interfere with agriculture)
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biomass typically isn’t replaced as quickly as it is used
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Intensive use of wood for energy leads to soil erosion, deforestation, desertification, air pollution, and degradation of water supplies
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use of agricultural crop residues depletes the minerals in the soil and lowers future productivity
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Sweden attempted to phase out all of its nuclear power, and replace it with biomass
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Biologists pointed out the many way’s growing large tracts would reduce biodiversity
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the projections for the amount of biomass was cut in half