Objectives
•
Describe fossil fuels and explain why coal is a fossil
fuel
•
Summarize the processes of nuclear fission and
nuclear fusion.
•
Explain how nuclear fission generates electricity
•
Explain how geothermal energy may be used as a
substitute for fossil fuels
•
Compare passive and active methods of harnessing
energy from the sun
•
Explain how water and wind can be harnessed to
generate electiricty
Fossil Fuels
•
Fossil fuel: a
nonrenewable resource
formed from the remains
of organisms
• Oil
• Coal
• Natural gas
•
Nonrenewable
resources: resources
which form at a rate
much slower than the
rate at which they are
consumed
•
Much of the energy
humans use every day
comes from the burning
fossil fuels.
Problems with Fossil Fuels
•
Impurities in fossil
fuels are a major
source of pollution
•
Burning fossil fuels
produce large
amounts of CO2,
which contributes to
global warming
Coal Energy
•
Coal is the most
abundant fossil fuel in the
world. 2/3 of all coal
deposits are in the US,
Russia, and China.
•
Coal is formed during
carbonization, which
occurs when partially
decomposed plant
material is buried in
swamp mud and
becomes peat.
•
As bacteria consume
some of the peat,
methane and CO2 are
released, and the
contents gradually
change until mainly
carbon remains.
•
Alternative Energy: Nuclear
Nuclear fission: process
by which the nucleus of an
atom splits into two or
more fragments
• releases neutrons &
energy
•
Newly released neutrons
strike and split nearby
nuclei, which causes the
release of more neutrons
and energy, initiating a
chain reaction
•
Uncontrolled fission
reactions escalate quickly
and result in a nuclear
explosion
•
Controlled reactions
produce heat which can be
used to generate electricity
How Fission Generates Electricity
•
Nuclear reactor:
specialized area where
controlled nuclear fission
is carried out
•
Chain reaction from
nuclear fission causes fuel
rods to become very hot.
•
Water is pumped around
the rods to absorb heat
•
The water is then pumped
into an area where it
becomes steam and turns
turbines which provide
power for electric
generators.
•
A third water area carries
away excess heat and
releases it into the
environment.
www.bio.miami.edu/beck/esc101/Chapter14&15.pp
t
Advantages/Disadvantages of
Nuclear Fission
• Nuclear power plants
do not burn fossil fuels
or produce air
pollution.
• However, they
produce radioactive
material which decay
slowly, so they must
be stored for
thousands of years
• The material emits
doses of radiation
which may be harmful
if not stored properly
Yucca Mountain
www.geology.fau.edu/course_info/fall02/
EVR3019/Nuclear_Waste.ppt
Geothermal Energy
• Renewable
resource: a natural
resource which can be
replaced at the same
rate at which it is
consumed
• Geothermal energy:
energy produced by
heat of the Earth
• The steam from hot
water passing near
magma produces a
large amount of energy
• Scientists drill wells to
reach the hot water
• The hot water drives
turbines, which
generate electricity.
Solar Energy
• Solar energy: energy
from the sun
• Solar energy can be
converted to heat
• In a passive system,
sunlight enters the
house and warms it
• An active system
includes solar
collectors, which
convert solar energy
into electricity.
Energy from Moving Water
•
Hydroelectric energy:
electrical energy produced
by the flow of water
•
Energy can be harnessed
from the running water of
rivers, streams, or ocean
tides
•
11% of the electricity in the
US is derived from
hydroelectric power
•
At a hydroelectric plant,
massive dams hold back
running water and channel
the water through water
spins turbines, which turn
generators and produce
electricity.
Energy from Biomass
•
Biomass: plant
material, manure, or any
other organic matter
used as an energy
source
• major source of
energy in many
developing countries
•
Bacteria which
decompose organic
matter produce gases or
liquids, which can be
burned.
•
More than half of all
trees that are cut down
are used as fuel for
heating or cooking.
Energy from Wind
•
Wind energy may be
used to produce
electricity in locations
with constant wind.
•
Wind farms: hundreds
of giant turbines which
produce enough energy
to meet the electric
needs of entire
communities.
•
Not practical
everywhere because the
wind does not always
blow
Preserving the Environment
•
Conservation:
preservation of natural
resources
•
Recycling: recovering
valuable or useful
materials from waste or
scrap
• requires energy, but uses less
than manufacturing new
resources
•
Fossil fuels can be
conserved by reducing the
amount of energy used
every day
•
Reducing the amount of
driving, using insulation for
a house, energy-efficient
appliances, all help
conserve energy