Hydroelectric Power

Advantages:

  • Concentrated potential energy (versus light)

  • Relatively inexpensive to operate a dam

  • Conversion of the forces of water to electric energy can be up to 90 % efficient

  • No chemical or waste heat pollution

  • Reservoirs can be used to breed fish


Disadvantages:

-Dams dramatically change natural flow of a river

  • Backs up one side, creates a reservoir which destroys preexisting habitats

  • Migration of spawning fish is disrupted

  • Other side is reduced to relative trickle which changes the countryside and wilderness recreation

  • Does not receive nutrient rich silt

-Reservoir-induced seismicity (earthquakes where there were none before)

  • The larger and faster a reservoir is filled the greater the intensity of the seismic activity

  • Reservoirs increase surface area of water

  • increase evaporation

  • 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:

  • Incredible potential (1% heat in Earth’s crust = 500 x Energy in all of Earth’s oil and natural gases)

  • once the initial investment is paid for, and energy is cheap

  • Geothermal Heat Pumps are the most efficient heating system available according to the EPA – lowest carbon emissions

  • Inexpensive, reliable electricity

  • 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:

  • initial expense, can cost thousands of dollars to dig out the land and lay the pipes

  • water used to generate electricity is not efficient enough

  • in the Geysers geothermal field ½ of the water was depleted after only 5% of the heat was tapped

  • some geothermal sites emit enough hydrogen sulfide (H2S) to require mitigation to meet air quality standards

  • pollution control is effective, but adds to the energy cost

  • surrounding land may subside as water from hot springs is removed

  • uncertainty about how long each geothermal well will last



Biomass Energy

Advantages:

  • Reduces dependence on fossil fuels

  • Makes use of waste reduction of waste disposal problem

  • 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

  • Biomass combustion produces significantly less sulfur and ash than bituminous coal

  • levels of carbon released can be absorbed by regenerating (planting trees) biomass

  • largest biomass power plant in North America uses sugar cane fiber and recycled urban wood to generate power for its milling and refining operations

  • excess energy supplies renewable electricity for nearly 60,000 homes

  • reduces dependence on oil by more than one million barrels per year


Disadvantages:

  • requires land/water to produce biomass

  • agricultural land needs both of these as well, so a shift to biomass production might raise food prices

  • some scientists propose the use of oils from desert shrubs (wouldn’t interfere with agriculture)

  • biomass typically isn’t replaced as quickly as it is used

  • Intensive use of wood for energy leads to soil erosion, deforestation, desertification, air pollution, and degradation of water supplies

  • use of agricultural crop residues depletes the minerals in the soil and lowers future productivity

  • Sweden attempted to phase out all of its nuclear power, and replace it with biomass

  • Biologists pointed out the many way’s growing large tracts would reduce biodiversity

  • the projections for the amount of biomass was cut in half