Environmental Science

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Environmental Science

• Renewable/Alternative Energy Sources
• Lecture Notes

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Biomass Energy

• Biomass garbage from organisms
• Dead trees, branches, yard clippings, left-over
  crops, wood chips, bark and sawdust from lumber
  mills (even manure)
• Trash that can't be recycled ? landfill ? using
  biomass for fuel cuts down landfill space

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Biomass to Electricity

• 60 million tons of biomass (amount produced by
  most states) ?2,000 megawatts of electricity
  (enough for 2 million homes!)
• How biomass works
• 1. Biomass collected in trucks ? taken to
  biomass power plant
• 2. Biomass burned ?boils water ? steam turns
  turbogenerators

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Landfill Gas

• Biomass also tapped at landfills (LANDFILL
  GAS)
• 1. Garbage decomposes ? methane gas
• 2. Pipelines collect methane gas ? burned in
  power plants to make electricity
• Also done on animal farms Manure decomposes ?
  methane gas ? burned at farm to make energy
• Using biomass does NOT add to global warming
  (unlike fossil fuels). WHY NOT??

Turning Landfill Gas into Energy (4")
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(No Transcript)
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The Future of Biomass

• Biomass is renewable because plant biomass can be
  regrown
• Another use of biomass is ethanol, a liquid
  alcohol fuel
• Ethanol used in cars designed to use alcohol fuel
  instead of gasoline
• Alcohol can also be mixed with gasoline to reduce
  dependence on oil

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Geothermal Energy

• "Geo" earth "thermal" heat
• Below earths crust, top layer of mantle is hot
  liquid rock called magma
• For every 328 feet below ground, temperature
  ?5.4oF. At 10,000 feet below ground, the
  temperature is hot enough to boil water.
• Deep under the surface, hot water can reach
  temperatures more than 300oF (water boils at
  212oF). It doesn't turn to steam because it is
  not in contact with the air.
• What are geysers? (Old Faithful pictured on the
  right)

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Geothermal Today

• In U.S., geothermally heated water is used in
  swimming pools and health spas
• In Southern California, hot water from
  underground is used to heat buildings during
  winter. Hot water runs through miles of insulated
  pipes to public buildings.
• In Iceland, many buildings/swimming pools are
  heated with geothermal hot water. The country has
  at least 25 active volcanoes and many hot springs
  and geysers.

Geothermal Heating (1")
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Geothermal Electricity

• Underground steam ? electricity in geothermal
  power plant
• 1. Holes drilled in ground pipes lowered
  into steam
• 2. Steam comes up pipes
• 3. Steam spins turbine blades and generator to
  make electricity
• 4. Steam cooled off in cooling tower and
  pumped back underground to be reheated by earth
• California's geothermal power plants produce
  about 1/2 of world's geothermally generated
  electricity (enough for 2 million homes)

Geothermal Electric Power Plant (4.5")
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Hydro Power

• Moving water ?kinetic energy ?electricity
• First used to turn wooden wheels attached to
  grinding wheels to grind (or mill) flour or corn
• Water can either go over the top of the wheel
  (see photograph at right), or the wheel can be
  placed in the moving river. The flow of the river
  turns the wheel at the bottom (see moving graphic
  in the upper right)

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Hydroelectricity

• Hydroelectric power ? kinetic
• energy of moving water ? electricity
• Dams built across large rivers
• Hydro power today is found in mountainous areas
  of states where there are lakes or reservoirs and
  along rivers
• Washington state leads nation in hydroelectricity
  ?87 is produced by hydroelectric facilities

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How a Hydro Dam Works

• 1. Water behind dam flows through intake pipe
  called penstock.
• 2. Water pushes against blades in a turbine.
• 3. Turbine spins generator to produce
  electricity. Electricity travels via electric
  lines to homes, schools, factories and
  businesses.

Hydroelectricity (2")
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Ocean Energy

• 3 basic ways to tap the ocean for its energy
• 1. ocean's waves
• 2. ocean's high and low tides
• 3. temperature differences in the water

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Wave Energy

• Moving waves ? Kinetic energy
• Wave turbine
• 1. Wave rises into chamber
• 2. Rising water forces air out of chamber
• 3. Moving air spins turbine to turn a generator
• 4. When wave goes down, air flows through
  turbine and back into chamber through doors that
  are normally closed
• Most wave-energy systems are very small and can
  be used to power a warning buoy or small light
  house

Wave Energy Video
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Tidal Energy
Tidal Electricity Generation Animation (1")

• Tides come into shore and are trapped in
  reservoirs behind dams. When tide drops, water
  behind dam is let out just like a hydroelectric
  power plant
• An increase of at least 16 feet between low to
  high tide is needed for tidal energy to work
• Only a few places where this tide change occurs
  around the earth. One plant in France makes
  enough energy from tides (240 megawatts) to power
  240,000 homes.

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Ocean Thermal Energy Conversion (OTEC)

• Uses temperature differences in ocean
• Sun warms surface water more than deep water
• Ocean's warm surface water is used to heat a
  fluid with a low-boiling point, such as ammonia
• Steam turns turbine ?activates generator to
  produce electricity

OTEC Video (4")
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Renewable Energy Pros

• 1. No shortage of renewable energy from the sun,
  wind and water and even stuff usually thought of
  as garbage (biomass). (Sunlight falling on the
  United States in one day contains more than twice
  the energy we consume in an entire year.
  California has enough wind gusts to produce 11
  percent of the world's wind electricity.)
• 2. Less pollution

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• 3. Renewable energy resource development ? new
  jobs for people and less oil we must buy from
  foreign countries.
• 4. Continued research has made renewable energy
  more affordable than 25 years ago. (The cost of
  wind energy has dropped from 40 per
  kilowatt-hour to less than 5. The cost of solar
  electricity, through photovoltaics has dropped
  from more than 1/kilowatt-hour in 1980 to
  20/kilowatt-hour today.)

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Renewable Energy Cons

• ? TAKES UP A LOT OF LAND
• 1. Solar thermal energy (often huge mirrors)
  needs large tracts of land as a collection
  site.
• 2. Average wind farm requires 17 acres of land
  to produce one megawatt of electricity, enough
  electricity for 750 - 1,000 homes. However,
  farms and cattle grazing can use the same land
  under the wind turbines.
• 3. Environment also impacted when constructing
  power plants, roads, transmission lines and
  transformers.

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• EVEN THOUGH A RENEWABLE POWER PLANT DOESNT
  RELEASE AIR POLLUTION OR USE FOSSIL FUELS, IT CAN
  STILL HAVE A NEGATIVE IMPACT ON THE ENVIRONMENT
• 1. Making PV cells uses toxic chemicals.
• 2. Wind farms could cause erosion in desert
  areas. Most often, winds farms affect the
  natural view because they tend to be located on
  or just below ridgelines. Bird deaths also occur
  due to collisions with wind turbines and wires.
• 3. Dams used in hydroelectric power cause
  farmland and forests to flood. Downstream, dams
  change the chemical, physical and biological
  characteristics of the river and land.