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Renewable Energy Renewable Energy Alternatives to Fossil Fuels

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Renewable Energy Renewable Energy Alternatives to Fossil Fuels Powered By Docstoc
					Renewable Energy
Alternatives to Fossil Fuels
    and Nuclear Power
• Alternative energy sources
  that are more or less
  continuously made available
  in a time framework useful to
  humans
   Nonrenewable Energy
• Energy sources that are
  dependent upon fuels or a
  resource that that may be
  used up much faster than it
  is replaced by natural
  processes
    Types of Renewable Energy
•   Solar
•   Water
•   Wind
•   Biomass
    –burning
    –conversion to liquid fuels
• Geothermal
• Solar-Hydrogen
Current Sources of Energy
    Direct Solar Energy
• Used to
  – Heat houses and buildings
  – Heat water
  – Create high temperature heat
  – Create electricity
Solar Energy Usage
   Passive Solar Heating
• Based on Architectural Design

• Considers exposure direction,
  windows, building materials,
  eaves

• Requires no energy to use
    Active Solar Heating
• Uses mechanical power and pumps
  to circulate air

• A heat absorbing fluid is heated by
  the sun and then transported into
  the structure

• High cost, needs maintenance,
  unattractive
         Water Heating
• Flat box with glass on top, black on
  the bottom, water tubes in middle
 –Hot water coming
  out of tubes is
  placed in top of
  tank
 –Cooler water from
  bottom is returned
  to collector
High Temperature Heating
• Solar Towers
  –many solar panels are used to
   focus solar energy for immediate,
   or later use
High Temperature Heating
• Solar Cookers - inexpensive
  –metal lined box and mirrors focus
   solar energy to cook food
        Solar Electricity
• Photovoltaic cells
  or solar cells
• When photons
  from sunlight hit a
  thin wafer of metal,
  a small electric
  current is
  produced
       Solar Electricity
• Many cells must be linked together
  to produce usable energy
• Mostly used in remote areas,
  calculators, watches
Costs of Photovoltaic Cells
 Solar-Hydrogen Energy-
         Theory
• Hydrogen gas can be used for
  energy in two ways:
 –burned directly - since no carbon,
  it burns cleanly, producing water

 –combined with oxygen gas to
  produce water (fuel cells)
  Solar-Hydrogen Energy
• Problem:
  –Hydrogen gas is very rare in
   the environment

 –H2 gas is costly to make
  through chemical reactions
  Solar-Hydrogen Energy
• Solution:
  –H2 and O2 can be produced
   easily by running a current
   through water - electrolysis

 –Solar cells can be used to
  create electricity to fuel
  electrolysis H2 gas
  Salt Water Solar Ponds
• Heat accumulates in bottom layer
  –Layer is pumped out and used for
   heating or
   electricity
 Fresh Water Solar Ponds
• Holes are dug and lined with black.
 –Water heats up, but heat is prevented
  from escaping
• Both methods are cheap, do not
  pollute
• Don’t require
  expensive storage:
  Save energy.
    Indirect Solar Energy
• Methods of creating electricity
 – Biomass Energy
 – Wind Energy
 – Hydropower
 – OTEC
 – Waves & Tides
     What is BIOMASS?
• Organic matter produced by
  photosynthetic producers

• Total dry weight of all living
  organisms at each trophic level in a
  food web

• Dry weight of all organic matter in
  an ecosystem; plant materials and
  animal wastes used as fuel.
    METHODS OF USING
     BIOMASS ENERGY
• Method #1
  –Burning Biomass to
   create heat
• Method #2
  –Gaseous Biofuels
  –Liquid Biofuels
    Method #1 - Burning
• Dung, Reeds, Wood

• Biomass must
  not be removed
  faster than it
  can be replaced
      Biomass - Burning
• Primarily used in
  developing countries
• Trash can also be
  burned
• Efficient when
  harvested locally
• Burning dung takes
  nutrients from fields
            METHOD #2
• Convert solid biomass into gas and
  liquid biofuels
• BIOGAS (60% methane)
• Ethanol
 –distilled and fermented grains
• Methanol
 –high cost: produced from sewage
  sludge, wood, wood wastes,
  agricultural wastes, garbage & coal
       Biogas - Landfills
• Puente Hills Landfill
•
• Uses local
  solid waste
  as source
       Landfill Mound
• “Capped” landfill mound
• Methane bubble trapped beneath
    Gas Extraction Wells
• Gas Extraction wells on top

• Reclaimed as a nature center

• Return of
wildlife
• Parks for
recreation
           Gas Wells
• Gas pressure,
  temp constantly
  monitored
• Automatic
  shutdown if
  necessary
         Burn-Off Pipe
• Burn-off for noxious materials
• Goes out regularly; has to be relit
  or BOOM! Someone on constant
  duty
      Gas Compressor
• Concentrates methane
   Turbine for Electricity
• Gas mixture burned
• Generates steam; turns turbine
  Ethanol and Methanol
• Excess grain stocks can be
  fermented by bacteria to
  produce these fuels which can
  then be burned as fuel
• Burning both of these fuels still
  produces CO2
           Methane
• Animal dung digested by
  bacteria, converted to methane

• Burning methane = >energy
  than burning dung

• Currently practiced on a small
  scale: great potential
YES, BIOMASS IS GOOD!
      PROS - BIOMASS
• A renewable resource if managed
  as one

• CO2 levels have no net increase

• Emits less SO2 and NO and CO2
  into the atmosphere per unit when
  compared to uncontrolled burning
  of coal
 Current Biomass Supplies
   Could Provide 30% of
    World’s Electricity
• Approximately 55% by year 2050
  Problems with Plantations
• 81% more land for same amount of
  energy when compared to solar
  cells
• HEAVY use of pesticides
• Pollution of drinking water
• Natural environment into plantation
  = no biodiversity
• Monoculture
  Problems with Plantations
• 80% of heat energy is lost when
  converted to electricity

• Paper mills and lumber companies
  occupy the fuel wood markets

• Urban areas require shipping

• Inefficient fireplaces let heat
  escape
  Pollutants from burning
         BIOMASS
• Wood smoke contains
  particulates and policycle
  aromatic hydrocarbons
 –ex bronchitis, emphysema,
  cancer, & other illnesses
 –820 estimated deaths per year
ETHANOL
PROS               CONS
• High octane      • Negative net energy
• Emission         • Larger fuel tank need
  reduction of     • High cost
  carbon dioxide   • Competition for
• Reduction of       cropland
  CO               • Smog formation
• Potentially      • Corrosive
  renewable
                   • Hard to start in cold
METHANOL
PROS             CONS
• High octane    •   Large fuel tank need
• Emission       •   Corrosive on metal,
  reduction of       rubber & plastic
  carbon dioxide •   Increased emissions
• Reduction of       of formaldehyde
  total air      •   Hard to start in cold
  pollution 30%- •   High cost
  40%            •   Created by coal =
                     high CO2 emissions

				
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posted:4/15/2012
language:English
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