Transcript Chpt 18 - fantinisfantastic

Alternative Energy
Chapter 18
Solar Energy
 Renewable
Energy Source
 Found every where at least part of
the year.
 Three
(3) Types:
– Passive Solar Heating
– Solar Water Heating
– Solar Cells
Passive Solar Heating

How it works:
–
–
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–
–
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Build your home facing south.
Large, double pane windows.
Thick walls & insulation on north side.
Concrete, adobe or stone construction.
Venting for hot air out during summer.
Drapes in winter to keep heat in at night.
Deciduous trees planted on south side
 Block
sunlight in summer
 Allow sunlight in winter
Passive Solar Heating
Passive Solar Heating

ADVANTAGES

DISADVANTAGES
– Free energy
– Unattractive
– Renewable
– Is there enough
available sunlight in
all areas?
– Clean
– Safe
– Construction costs
– Requires backup
heat source
Solar Water Heating
 How
it works:
– “Solar Collectors” on roof
 Pipes
with water or anti-freeze are coiled
through box on roof.
 Heated water transferred to basement.
 Heat exchanged to fresh water; water
pumped back to roof to be reheated.
Solar Water Heating
Solar Water Heating

ADVANTAGES

DISADVANTAGES
– Free energy
– Unattractive
– Renewable
– Is there enough
available sunlight in
all areas?
– Clean
– Safe
– Requires a backup
hot water source
Solar Cells (Photovoltaics)
 How
it works:
– Converts sunlight to electricity!
– Sunlight strikes semi-conductor
– Electrons are excited and move; creates
electricity.
– Energy can be stored in a chemical
battery for use when sunlight is absent.
Photovoltaics (Solar Cells)
Solar Cells

ADVANTAGES

DISADVANTAGES
– Free energy
– Expen$ive!
– Renewable
– Need large surface area
– Clean
– Unattractive
– Safe
– Is there enough
available sunlight in all
areas?
– Requires a backup
electricity source
Wind Energy
 How
it works:
– Sunlight heats Earth’s surface
– Warm air rises; cooler air replaces it (wind)
– Wind (mechanical E) turns giant blades
– Connected to a generator; creates
electricity
Wind Energy

ADVANTAGES

DISADVANTAGES
– Free energy
– Unattractive
– Renewable
– Few regions with
consistent winds
– Clean
– Well developed
technology
– Electricity is cheaper
per watt than coal
produced.
– Noisy
– Interfere with
microwave
communications
– Harm birds & wildlife
Wind Energy
Hydroelectricity
 How
it works:
– Dam is constructed to make a reservoir
– Need height change to create enough
power of moving water
– Flowing water through dam turns
turbines, turns generator, makes
electricity
Hoover Dam
Hydroelectricity

ADVANTAGES
– Free energy
– Renewable
– Clean
– Flood control
– Reservoir for recreation
& irrigation

DISADVANTAGES
– Disrupts ecosystems &
floods upstream land
– Tremendous
environmental damage
during construction
– Dam construction is
extremely expensive
– Limited to areas with
rivers & streams
Geothermal Energy
 How
it works:
– Uses Earth’s heat to create steam to
make electricity
– Hot Dry Rock Method
 Pump
cold water below ground
 Turns to steam
 Extract pressurized steam
 Turns turbine, turns generator, creates
electricity
Geothermal Energy
Geothermal Energy
Geothermal Energy

ADVANTAGES
– Free energy
– Potentially
Renewable***
– No greenhouse gases
– Minimal environmental
damage during set-up

DISADVANTAGES
– Limited availability on
Earth.
– Earth takes a long time
to replace the heat.***
Biomass
 How
it works:
– Burn organic matter to produce heat
– Examples:
 Wood
(#1 fuel in world usage)
 Municipal Waste (garbage)
 Sugar cane (Hawaii)
 Chicken droppings
– Convert to other products
 Corn
to ethanol (gasoline additive)
Waste to Energy Plant
Biomass

ADVANTAGES

DISADVANTAGES
– Reduces “wastes”
– CO2 emissions
– Renewable
– Noxious gases
released
– Conserves fossil
fuels
– Sell extra electricity
to public
– Who wants to live
near a plant that
burns trash or
chicken poop?
Tidal Energy
 How
it works:
– Offshore Turbines
 Similar
to underwater windmills
– Tidal Barrage
 Similar
to hydroelectric dams
Offshore Turbines
Tidal Barrage
Tidal Energy

ADVANTAGES

DISADVANTAGES
– Free energy
– Affects ecosystems
– Renewable
– Unattractive
– Clean (nonpolluting)
– Expensive to build
– Affects shipping
Energy Concepts
& Efficiency
Introductory Energy Concepts
 Energy
– “The ability to do work”.
 KEY
CONCEPT!
– The amount of energy in the universe is
constant.
Six (6) Forms of Energy

Mechanical
– The energy of moving
things.


EX: wind, moving
water
Electrical
– The energy of moving
electrons

Heat
– The energy of
temperature change

Hotter temperatures
can do more work.
Six (6) Forms of Energy

Light
– The energy of moving
photons

Chemical
– The energy stored in
the bonds between
atoms.


EX: food, wood,
gasoline, batteries,
coal, oil…
Nuclear
– The energy stored
between the subatomic
particles

EX: Nuclear power
plants
Kinetic vs. Potential Energy
 Kinetic
Energy
– The energy of something moving.
– EX: Ball rolling down a hill.
 Potential
Energy
– Stored energy; can be moved and used
when needed.
– EX: Ball on the edge of a hill.
Kinetic vs. Potential

At Top = 100% potential

At Bottom = 100% kinetic
1st Law of Thermodynamics
 “Conservation
of Energy Law”
– Energy can neither be created nor
destroyed.
 Energy
in the universe is constant.
 If you can’t destroy energy, you CAN change
its form!
– EX: Matches
– EX: Light Bulb
2nd Law of Thermodynamics
 “Energy
Quality Law”
– When energy changes form, some
useful energy is always degraded to
lower quality, less useful energy.
 Low
temperature heat is the least useful
energy form!
– EX: 90% of energy in gas (chemical) is
changed to heat!
Energy Efficiency

Net Energy
– Total E – (E input & wasted E)

Energy Efficiency
– % of total E that does work.
– Wasted energy reduces E efficiency

Life cycle costs
– Initial energy costs + lifetime operating costs
Electricity



The movement of
electrons.
Created by moving a
conducting material
(copper wire)
through a magnetic
field.
“Electric Generator”
Coal & Turbine Pictures