Environmental Science: Toward a Sustainable Future Richard T. Wright

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Environmental Science Toward a Sustainable
Future Richard T. Wright
Chapter 14

• Renewable Energy
• PPT by Clark E. Adams

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Renewable Energy

• Putting solar energy to work
• Indirect solar energy
• Renewable energy for transportation
• Additional renewable-energy options
• Policy for a sustainable-energy future

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Renewable-energy Use in the United States
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Examples of Renewable Energy Sources
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Putting Solar Energy to Work
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Principles of Solar Energy
Constant Abundant Free Everlasting
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Hurdles in Using Solar Energy

• Collection
• Conversion
• Storage
• Cost-effectiveness

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Terms and Definitions Solar Heating Systems

• Active moves water or air with pumps and blowers
• Passive moves water or air with natural
  convection currents or gravity

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Components of Active or Passive Solar Heating
Systems?

• Flat-plate collector
• Water pump
• Blowers
• Heat exchanger
• Improved insulation
• Earthen berms

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Solar Heating of Water Flat-plate Solar Collector
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Solar Water Heaters
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Solar Space Heating
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Solar Building Siting
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Landscaping in Solar Heating and Cooling
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Solar Production of Electricity
Photovoltaic Cell
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How Photovoltaic Cells Work Part 1

• Each cell consists of two thin mylar layers.
• Lower layer has atoms with single electron in
  outer orbit easily lost.
• Upper layer has atoms lacking one electron in
  outer orbit easily accepts electrons.

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How Photovoltaic Cells Work Part 2

• Kinetic energy from sunlight dislodges electrons
  from lower layer creates an electric potential
  between the two layers.

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How Photovoltaic Cells Work Part 3

• The potential provides the energy for an
  electrical current through the rest of the
  circuit.
• Electrons from lower layer flow through a device
  back to upper side.

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The Market for PV Cells
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Concentrating Solar Power

• PV power plants
• Solar-trough collectors
• Power towers
• Dish-engine system

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The Solar-trough Collector
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Power Tower
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Solar Dish Engine System
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Disadvantages of Solar Energy Technologies

• Expense
• Only works during the day
• Requires backup energy sources, e.g., batteries
• Some climates not sunny enough

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Hidden Costs of Traditional Energy Sources

• Air pollution
• Strip-mining
• Nuclear wastes

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Indirect Solar Energy

• Hydropower
• Wind power
• Biomass energy

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Wind Power Benefits or Drawbacks?

• Size limitations of wind turbines
• Megawatts of electricity produced
• Level of pollution generated

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Wind Power Benefits or Drawbacks?

• Level of environmental degradation
• Geographical distribution of energy produced
• Aesthetics

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Biomass Energy

• Burning firewood
• Burning wastes
• Burning biogas (methane)

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Biomass Energy Benefits or Drawbacks?

• Availability of the biomass resource
• Access to the biomass resource
• Public acceptance and utilization of biomass
  energy
• Past history of human harvests within a maximum
  sustained yield

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Renewable Energy and Transportation

• Biofuels ethanol and biodiesel
• Hydrogen the fuel for the future

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HydrogenOxygen Fuel Cell
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Fuel Cells Benefits or Drawbacks?

• Substitute for fossil fuels
• Pollution factor
• Production technology
• Portability
• National distribution system

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Additional Renewable Energy Options

• Geothermal energy
• Tidal power
• Ocean thermal-energy conversion (OTEC)

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Geothermal Energy Benefits or Drawbacks?

• Consistent source
• Level of pollution
• Cost-effectiveness
• Technology required for extraction
• Geographical distribution of energy produced

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Geothermal Heat Pump System
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Tidal Power Benefits or Drawbacks?

• Consistent source
• Level of pollution
• Cost-effectiveness
• Technology required for extraction
• Geographical distribution of energy produced

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OTEC Benefits or Drawbacks?

• In an average day the heat absorbed by the
  surface water in only one square mile is
  equivalent to the burning of 7,000 barrels of oil
  
• Cost effectiveness to capture and distribute heat
  energy
• Industrial interest in the OTEC alternative

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Policy for a Sustainable Energy Future

• National energy policy
• A clean energy blueprint

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A Clean Energy Blueprint

• Supply side
• Establish a Renewable Portfolio Standard
• Maintain production tax credits
• Extend net metering
• Substantially increase research-and-development
  on renewable energy and efficiency

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A Clean Energy Blueprint

• Demand side
• Improve efficiency standards
• Enhance building codes
• Provide incentives for combined heat and power
  facilities
• Raise fuel economy (CAFÉ) standards
• Increase research and development on
  high-efficiency vehicles (hybrid electric and
  fuel cell vehicles).

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End of Chapter 14