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Chapter 13 Renewable Energy and Conservation Saving Energy at Home Overview of Chapter 13 Direct Solar Energy Heating Buildings and Water Solar Thermal Electric ... – PowerPoint PPT presentation

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Title: Chapter%2013%20Renewable%20Energy%20and%20Conservation

Chapter 13Renewable Energy and Conservation
Overview of Chapter 13
  • Direct Solar Energy
  • Heating Buildings and Water
  • Solar Thermal Electric Generation
  • Photovoltaic Solar Cells
  • Indirect Solar Energy
  • Biomass Energy
  • Wind Energy
  • Hydropower
  • Other Renewable Energy Sources
  • Geothermal Energy
  • Tidal Energy
  • High and Low Technology Energy Solution
  • Hydrogen and Fuel Cells
  • Energy Efficiency

Direct Solar Energy
  • Varies with latitude, season, time of day, and
    cloud cover
  • Current technology

Heating Buildings and Water
  • Passive solar energy
  • system of putting the suns energy to use without
    requiring mechanical devices to distribute the
    collected heat
  • Certain design features can enhance passive solar
    energys heating potential
  • South facing windows (in N. hemisphere)
  • Well insulated buildings
  • Attic vents
  • Overhangs and solar sunspaces
  • Why dont more homes have passive solar energy

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Solar sunspace
  • Utilizes passive solar energy to heat and cool
  • Can be added to existing homes

Heating Buildings and Water
  • Active Solar Energy
  • System of collecting and absorbing the suns
    energy, and using pumps or fans distribute the
    collected heat
  • Most common
  • Series of collection devices on roofs or in
  • Typically a black panel or plate
  • Used to heat water

Heating Buildings and Water
  • Solar Thermal Electric Generation
  • Means of producing electricity in which the suns
    energy is concentrated by mirrors or lenses to
    either heat a fluid filled pipe or drive a
    Stirling engine
  • Examples
  • More efficient than other solar technologies
  • Benefits
  • No air pollution
  • No contribution to global warming or acid

Solar Thermal Electric Generation
  • Solar thermal plant in CA uses troughs to focus
    sunlight on fluid filled tube

Photovoltaic Solar Cells
  • Thin cells are treated with certain metals so
    that they generate electricity when they absorb
    solar energy
  • Convert sunlight directly into energy
  • Pros
  • No pollution, minimal maintenance
  • Used on any scale
  • Lighted road signs
  • Entire buildings
  • Cons
  • Not very efficient
  • Requires a great deal of land

Photovoltaic Solar Cells
  • Benefit to utility companies
  • Rural areas in developing countries it is more
    economical to use PV solar cells
  • Future - can be incorporated into building
  • Roofing shingles
  • Tile
  • Window glass

Cost of Electrical Power Plants
  • Other technologies
  • Indirect Solar Energy
  • Combustion of biomass
  • Wind energy
  • Hydropower

Indirect Solar Energy
  • Biomass
  • Plant materials used as fuel
  • Ex wood, crop wastes, sawdust, and animal wastes
  • Contains energy from sun via photosynthesizing
  • Renewable when used no faster than it can be
  • Can convert to biogas or liquids
  • Ethanol and methanol
  • Pros and cons

Advantages and Disadvantages of Biomass
  • Advantages
  • Reduces dependence on fossil fuels
  • Often uses waste materials
  • If trees are planted at same rate biomass is
    combusted, no net increase in atmospheric CO2
  • Disadvantages
  • Requires land, water and energy
  • Can lead to
  • Deforestation
  • Desertification
  • Soil erosion

Indirect Solar Energy
  • Wind Energy
  • Electric or mechanical energy obtained from
    surface air currents caused by solar warming of
  • Worlds fastest growing source of energy
  • Wind results from sun warming the atmosphere
  • Varies in direction and magnitude
  • New wind turbines harness wind efficiently

Wind Energy
  • Most profitable in rural areas with constant wind
  • Few environmental problems
  • Kills birds and bats
  • No waste- clean source of energy
  • Biggest constraints
  • Cost
  • Public resistance

Indirect Solar Energy
  • Hydropower
  • Form of renewable energy reliant on flowing or
    falling water to generate mechanical energy or
  • Suns energy drive hydrologic cycle
  • Most efficient energy source (90)

  • Generates 19 of worlds energy
  • Traditional hydropower
  • Only suited for large dams
  • New technology
  • May be able to utilize low flow waterways
  • Impacts of Dams
  • Changes natural flow of rivers
  • Disrupts migratory fish patterns
  • Potential dam breaks

Three Gorges Dam
  • 1990s China began work on the Three Gorges Dam
    (TGD), which will meet several goals
  • Designed to produce electricity equivalent to 18
    nuclear power plants or large coal power plants ?
    advantage because air pollution is a concern in
  • Agricultural productivity downstream will be
  • Will be used for transportation, commercial
    fishing and recreation
  • Range of problems associated w/ building dams
  • China had difficulty finding investors since
    uncertainty about design, construction and
    effectiveness was so great

Other Indirect Solar Energy
  • Ocean waves
  • Produced by winds
  • Has potential to turn a turbine- and create
  • Ocean Temperature Gradients
  • Use difference in temperature of surface and deep
    water to create electricity

Other Renewable Energy Sources
  • Geothermal Energy
  • Energy from the Earths interior for either space
    heating or generation of electricity
  • Typically associated with volcanism
  • From Hydrothermal Reservoirs (right)
  • Created by volcanoes
  • Reservoirs used directly for heat or to generate
  • Renewable?
  • Environmentally benign?

Geothermal Energy
  • From hot, dry rock
  • Technology exists but is expensive
  • Geothermal heat pumps
  • Use difference in temperature between surface and
  • Great for heating buildings
  • Expensive installation

Other Renewable Energy Sources
  • Tidal Energy
  • Form of renewable energy that relies of the ebb
    and flow of the tides to generate electricity
  • Typical difference between high and low tide is
    1-2 ft but range can be higher
  • Narrow bays may have greater variation
  • Energy can be captured with
  • A dam across the bay
  • A turbine similar to a wind turbine

Energy Conservation vs. Energy Efficiency
  • Human requirements for energy will continue to
    increase as the population increases and as
    developing countries raise their standards of
  • Energy conservation using less energy by
    reducing energy use and waste, for example
  • Example
  • Energy efficiency using less energy to
    accomplish a given task, as for example with new
  • Example
  • Important environmental benefits from greater
    energy efficiency and conservation
  • Using energy efficient appliance could reduce CO2
    emissions by millions of tons each year (slowing
    climate change)
  • Reduce air pollution, acid precipitation and
    other environmental damage

Hydrogen as a Fuel Source
  • H2 contains large amounts of available energy
  • Gas at RT, liquid when cooled to -435 F
  • Explode when combined with the O2 ? releasing
    energy and forming water
  • Advantages to Hydrogen as a fuel source
  • Very high energy density
  • Can be produced from any electrical source
  • Electrolysis (see illustration on next slide)
  • No greenhouse gases and few other pollutants
  • Can be use in vehicles
  • Disadvantages to Hydrogen as a fuel source
  • Highly volatile (requires special storage)
  • Relatively inefficient

Hydrogen as a Fuel Source-Electrolysis
Hydrogen Fuel Cell
  • Fuel cell
  • Device that directly converts chemical energy
    into electricity
  • Requires hydrogen from a tank and oxygen from the
  • Similar to a battery, only the reactants are
    supplied from outside source

Applications of Fuel Cells
  • Although technology is improving, not commonly
  • Vehicles
  • Not yet commonly available
  • Hydrogen is not yet readily available as a fuel
  • Batteries in cells phones or laptops

Energy Consumption Trends and Economics
  • Lower energy intensity implies economy is more
    energy efficient as it generates wealth
  • Energy Trends in Developing Countries
  • Per capita energy consumption is substantially
    less in developing countries than in
    industrialized countries

Energy Efficient Technologies
  • Compact Fluorescent light bulbs
  • Condensing furnaces
  • Super-insulated buildings (right)
  • Energy efficient appliances
  • National Appliance Energy Conservation Act
  • Automobiles
  • Aircraft technology

  • Production of two useful forms of energy from the
    same fuel
  • Cost effective on small or large scale

Energy Savings in Commercial Buildings
  • Energy services companies often offer their
    assistance so that businesses make little or no
    financial outlay
  • How does this work?

Electric Power Companies and Efficiencies
  • Traditionally to meet future power needs,
    electric utilities planned to build new power
    plants or purchase additional power from
    alternative sources
  • Now they avoid these large expenses by
    demand-side management help electricity
    consumers save money by reducing energy costs
  • How?
  • Improvements
  • US electric power plants are important target for
    improved energy efficiency much heat is lost
    during generation of electricity
  • Improve our electric grids about 10 of
    electricity is lost during transmission right now

Saving Energy at Home
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