Chapter 13 Renewable Energy and Conservation

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Chapter 13Renewable Energy and Conservation
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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

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Net Energy Yield

• Net Energy Yield the total useful energy
  derived from a resource minus the energy required
  to obtain the resource and make it available.
• Low Nuclear Energy
• High passive solar

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Cogeneration

• Production of two useful forms of energy from the
  same fuel

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Electrical Grids

• Electrical plants are attached to a grid
  connected to each other and to their customers.
• Peak demand time of day when electricity is
  most needed (dinner time)
• Brownout power not sufficient to meet demand,
  grid does not completely fail
• Blackout malfunction in power plant/grid

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August 14 2003 Blackout

• Affected several cities in the North East,
  including ours.
• High demand, high temperatures, and faulty
  powerlines were to blame.

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Going off the grid

• Benefits.
• Cons.

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Increasing Efficiency

• Cogeneration
• Simultaneous production of both electricity and
  steam in the same plant.
• Take waste heat from one process and use it in
  another process

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Increasing Efficiency

• Energy efficient appliances are more costly, but
  over the lifetime of appliance save money.

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Increasing Efficiency

• Regular lightbulbs much less efficient than
  compact fluorescent bulbs
• Negative mercury

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Increasing Efficiency

• Make automobiles more efficient
• US Car companies complain about cost efficiency
• US standards are far below those of other
  developed countries
• Personal options
• Drive more efficiently
• Keep car in shape
• Plan/combine trips
• Buy efficient car

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Hybrids
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Hybrids
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Hybrids

• Internal combustion engine and a rechargeable
  battery
• Battery charged by regenerative breaking or by
  plugging in
• Smart meter system allow for recharge during off
  peak hours
• Energy source should come from renewable
  source, otherwise its just a shift in point
  source pollution

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  67-invention-nation-super-hybrid-video.htm

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Direct Solar Energy

• Varies with latitude, season, time of day, and
  cloud cover

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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

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Window placement
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Tree Placement
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Solar Cooker
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Solar sunspace

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

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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
  fields
• Typically a black panel or plate
• Used to heat water

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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
• More efficient than other solar technologies
• Benefits
• No air pollution
• No contribution to global warming or acid
  precipitation

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Solar Thermal Electric Generation
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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
• No pollution and minimal maintenance
• Used on any scale
• Lighted road signs
• Entire buildings

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Photovoltaic Solar Cells

• Can be incorporated into building materials
• Roofing shingles
• Tile
• Window glass

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Cost of Electrical Power Plants
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Indirect Solar Energy

• Biomass
• Plant materials used as fuel
• Ex wood, crop wastes, sawdust, and animal wastes
  
• Contains energy from sun via photosynthesizing
  plants

• Renewable when used no faster than it can be
  produced
• Can convert to biogas or liquids
• Ethanol and methanol

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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

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Indirect Solar Energy

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

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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

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Indirect Solar Energy

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

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Hydropower

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

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Other Indirect Solar Energy

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

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Other Renewable Energy Sources

• Geothermal Energy
• Energy from the Earths interior for either space
  heating or generation of electricity
• From Hydrothermal Reservoirs (left)
• Created by volcanoes
• Reservoirs used directly for heat or to generate
  electricity

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Geothermal Energy

• From hot, dry rock
• Geothermal heat pumps
• Use difference in temperature between surface and
  subsurface
• Great for heating buildings
• Expensive installation

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  rmal_home-basics

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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
• Narrow bays may have greater variation
• Energy can be captured with
• A dam across the bay
• A turbine similar to a wind turbine

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Hydrogen as a Fuel Source

• 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

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Hydrogen as a Fuel Source-Electrolysis
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Hydrogen Fuel Cell

• Fuel cell
• Device that directly converts chemical energy
  into electricity

• Requires hydrogen from a tank and oxygen from the
  air
• Similar to a battery, only the reactants are
  supplied from outside source

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Future Applications of Fuel Cells

• Vehicles
• Not yet commonly available
• Hydrogen is not yet readily available as a fuel
  source
• Batteries in cells phones or laptops

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Energy Consumption Trends and Economics
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Energy Efficient Technologies

• Compact Fluorescent light bulbs
• Condensing furnaces

• Super-insulated buildings (right)
• Energy efficient appliances
• Automobiles
• Aircraft technology

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Energy Savings in Commercial Buildings
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Saving Energy at Home
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