Earth Science 4.2 Alternate Energy Sources
Alternate Energy
Sources
Alternate Energy Sources

Key Concepts:
 What are the advantages of using solar
energy?
 How do nuclear power plants use nuclear
fission to produce energy?
 What is wind powers potential for providing
energy in the future?
 How do hydroelectric, geothermal, and tidal
power contribute to our energy resources?
Solar Energy

Solar Energy is by far the Earth’s
most abundant energy source

Every second the total energy
Earth receives from the sun
amounts to more than 10,000
times the total amount of energy
used by all human societies in a
day

Solar energy has two advantages:
the fuel is free and it’s
nonpolluting
Solar Energy

The simplest and most widely
used solar energy systems are
passive solar collectors such as
south-facing windows.

As sunlight passes through the
glass, objects in the room absorb
the heat. These objects radiate
the heat, which warms the air.
Solar Energy

More elaborate systems for
home heating use an active
solar collector.

These roof mounted boxes
are usually large panels
covered with plastic or
glass. The heat they collect
can be transferred by
circulating air or liquids
through the piping.

Solar collectors are also
used to heat hot water
Solar Energy

Another type of solar collector uses photovoltaic cells that
convert sunlight directly to energy that can be stored in battery
systems
Nuclear Energy

Nuclear power meets about 7% of
the energy demand of the United
States

The fuel for plants comes from
radioactive materials that release
energy through nuclear fission.

In nuclear fission, the nuclei of
heavy atoms such as uranium-235
are bombarded with electrons. The
uranium nuclei then split into smaller
nuclei and emit neutrons and heat
energy.
Nuclear Energy

The neutrons that are emitted then bombard the nuclei of
adjacent uranium atoms, producing a chain reaction.

If the reaction continues in an uncontrolled manner, fission
releases an enormous amount of energy as an atomic
explosion
Nuclear Energy

In a nuclear powerplant however, the
fission material is controlled by
moving neutron-absorbing rods into or
out of the reactor

The result is a controlled nuclear
chain reaction that releases great
amounts of heat.
Nuclear Energy

At one time, energy experts thought nuclear power would be
the solution to all the Earth’s energy needs.

Several issues have developed in the past few years that have
slowed the development of nuclear energy

First: the cost of building safe nuclear facilities has increased.
Secondly: serious hazards are associated with the disposal
and storage of nuclear waste
Third: Severe accidents in the past few decades, Three Mile
Island and Chernobyl, have revealed that nuclear energy
facilities have serious safety concerns.


Wind Energy

According to experts, if just the winds
of North and South Dakota could be
harnessed, they would provide 80%
of the electrical energy used in the
United States

Some experts estimate that in the
next 50 to 60 years, wind power
could meet 5 to 10 percent of the
country’s demand for energy

Obstacles to development are
technical advances, noise pollution,
and cost of large tracts of land in
populated areas.
Hydroelectric Power

Like wind, moving water has been
around for centuries ad used as
an energy source

Hydroelectric power is power
generated from falling water being
used to run turbines that produce
electricity

The water held in a reservoir
behind a dam is a form of stored
energy that can be released
through the dam to produce
electric power
Geothermal Energy

On a commercial level, Geothermal
Energy is harnessed by tapping natural
underground reservoirs of steam and hot
water.

Hot water is used directly for heating and
to turn turbines to generate electric power

On a local level, geothermal energy can
be used to reduce heating/cooling costs
when it is combined with other systems
such as passive or active solar systems.
Water beneath the ground can be run
through a house foundation to bring the
foundation up to a level where less
energy is used to heat the house.
Tidal Power

The development of tidal power is an
area of energy exploration that is just
now being explored for it’s potential to
generate power

Tidal power is harnessed by building a
dam across the mouth of a bay in
coastal areas with a large tidal range.
The strong in-out flow of the tides is
used to drive turbines much like a
hydroelectric dam. These turbines than
generate electricity.

Tidal power isn’t economical unless the
rate of water flow is enough to generate
electricity at a sufficient rate. If the tides
are too strong however, they will tear the
tidal dams apart.
Tidal Power: Passamaquoddy Bay
Tidal Power
http://www.mainetidalpower.com/development/in
dex.html
Computer Lab Project:

Create a one page report on one of the
following topics
 Solar Energy and solar collectors
 Wind Energy and Wind Turbines
 Geothermal Energy
 Tidal Power: Passamaquoddy Bay Tidal
Project