Name: ___________________________________________________________________ Date: ______________________________ Period: __________
Chapter 25: Energy Resources
25.1 Conventional Energy Resources
Main Idea: Biomass and fossil fuels store energy from the Sun.
Earth’s Main Energy Source
 The energy that humans and all other organisms use comes mostly from the Sun.
o
Plants are producers—they capture the Sun’s light energy in the process of photosynthesis.
o
Organisms called consumers eat producers and use that stored energy for their own life processes.

Humans use energy to keep them warm in cold climates, cook food, pump water, and
provide electricity. There are kinds of fuel sources available to humans for this energy

Most of these fuels store energy that originated from the Sun.
Fuels: materials that are consumed to produce energy.
Biomass Fuels
 The total amount of living matter in an ecosystem is its biomass.
Biomass Fuel: fuels derived from living things (and they are renewable resources).
 Plants and other biomass materials burn readily because of the presence of hydrocarbons—molecules
with hydrogen and carbon bonds only.
o
Wood - Humans have been using wood for fuel for thousands of years. Billions of people, mostly
in developing countries, use wood as their primary source of fuel for heating and cooking.
o
Field Crops - The simplest way to use field crops, such as corn, hay, and straw, as fuel is to burn
them. Crop residues left after harvest, including the stalks, hulls, pits, and shells from corn,
grains, and nuts, are other sources of energy.
o
Fecal Material - Feces from cows often meet the energy needs of people in developing
countries with limited forest resources.
Peat
 Bogs are poorly drained areas with spongy, wet ground composed mainly of dead and decaying plant
matter. Over time, as plant material in a bog is compressed by the weight of water and by other
sediments that accumulate, it becomes a light, spongy material called peat (precursor to coal).
o
Highly decomposed peat burns with greater fuel efficiency than wood.
o
Today, peat is used to heat many homes in eastern and northern Europe, and the United States.
Fossil Fuels
Fossil Fuels: energy sources that formed over geologic time as a result of the compression and
decomposition of plants and other organic matter.

Fossil fuels are nonrenewable resources because their formation occurs over millions of years, but
we are using them at a much faster rate.

Although fossil fuels are diverse in their appearance and composition, all of them originated from
organic matter trapped in sedimentary rock.
Types of Fossil Fuels
 The three main kinds of fossil fuels are Coal, Oil (or Petroleum), and Natural Gas
Coal Formation and Types
Burial  Pressure  Heat  Time
Peat (not yet coal)
Lignite
Soft, brown, low-grade coal with low
sulfur content—less than 1%.
Because the carbon concentration in
lignite is generally around 40%, it is
inefficient as a fuel.
Bituminous
Carbon concentrations as high as
85%. When it burns, it releases
carbon dioxide and gases containing
sulfur and nitrogen in the air,
causing air pollution.
Oil Formation
The
remains
of
tiny
organisms and sediments are
deposited on the ocean
bottom and accumulate to
form sediment layers.
Sediment
layers
get
pressed down by the
weight of overlying layers
and become sedimentary
rocks.
With further burial, organicrich rock layers are subjected
to increasing pressure and
temperature and undergo
chemical & bacterial changes,
resulting in the formation of
oil and natural gas.
Anthracite
Carbon concentrations as high as 90
to 95%, and it stores more energy
and burns cleaner than other coal
types. However, less than 1% of the
coal reserves in the U.S. are
anthracite.
Oil and gas migrate upward
through spaces in rock until
an impermeable barrier is
reached.
Oil (Petroleum) and Natural Gas

Natural gas forms along with oil and is found beneath layers of solid rock, which prevent the gas from
escaping to Earth’s surface.

Oil shale is a fine-grained rock containing a solid, waxy mixture of
hydrocarbon compounds called kerogen.
o
When kerogen vapor is extracted from oil shale, it can be condensed
to form a heavy, slow-flowing, dark-brown oil known as shale oil.
o
Oil shale is found primarily in sedimentary rocks.

One of the most abundant sources of oil shale known is the
Green River Formation in Utah (see darker regions on right).
Name: ___________________________________________________________________ Date: ______________________________ Period: __________
25.2 Alternative Energy Resources
Main Idea: Many resources other than fossil fuels can be developed to meet the energy needs of people on Earth.
Solar Energy
The Sun is the source of most of the energy on Earth. The main advantages of solar energy are that sunlight
is free and it does not directly cause pollution.
 Nonrenewable fossil fuels (oil, coal, and natural gas) are used to generate approximately 85 percent of the
total energy consumed for electricity, heat, and transportation in the U.S.
o
Scientists, private companies, and government agencies are all studying renewable resources, such as
solar energy, as alternatives to traditional energy resources, including fossil fuels.
Passive Solar Heating
o
Floors and walls made of concrete, adobe, brick, stone, or tile have heat-storing capacities and can help
to hold thermal energy from the Sun inside a home.
o
Solar energy that is trapped in materials and slowly released is called passive solar heating.
Active Solar Heating
o
Active solar-heating systems include collectors such as solar panels that absorb
solar energy and fans or pumps that distribute the energy throughout a house.
Photovoltaic Cell: a thin, transparent wafer that converts sunlight into electrical energy and is
made up of two layers of two types of silicon.

Photovoltaic cells are reliable, quiet, and typically last more than 30 years.
Hydroelectric Energy
 Hydroelectric power is generated by converting the energy of free-falling water to electricity.
o
Today, hydroelectric power provides about 20% of the world’s electricity and
6% of its total energy.
 Ocean water is another potential source of energy. The energy of motion in waves,
which is created primarily by wind, can be used to generate electricity.
Geothermal Energy

Geothermal Energy is produced by Earth’s naturally
occurring heat, steam, and hot water.
o
In areas where large amounts of geothermal energy are
released, which usually coincide with plate boundaries,
geothermal energy can be used to produce electricity.
Wind Energy
 Windmills in the Netherlands have been capturing wind power for human use for 2000+ years.
o
Experts suggest wind power could supply more than 10% of the world’s electricity by 2050.
o In 2012, the U.S. accounted for 26% and Europe 48% of the world’s total wind energy output.
Nuclear Energy
 Nuclear fission is the process in which a heavy nucleus (mass number greater than 200) divides to form
smaller nuclei and one or two neutrons. This process releases a large amount of energy.
 Nuclear reactors rely on fission to generate heat.
o
Heated water is converted to steam which turns a
turbine to generate electricity.
 In the 1950s, scientists suggested that nuclear power
could produce electricity at a much lower cost than coal
and other types of fossil fuels. Nuclear power plants do not
produce carbon dioxide or any other greenhouse gases.
 After 50 years of development, nuclear reactors are
currently producing only 17 percent of the world’s electricity. High operating costs, poor reactor designs,
and public concerns about radioactive wastes have contributed to the decline of nuclear power.
Biofuel
 Ethanol is a liquid produced by fermenting crops such as barley, wheat, and corn that can be blended with
gasoline to reduce consumption of fossil fuels.
o
Ethanol fuels burn more cleanly than pure gasoline.
o
Biodiesel can be manufactured from vegetable oils, animal fats, or recycled restaurant greases.

Biodiesel is safe, biodegradable, and reduces air pollution.
Comparing the Alternatives
Energy Type
Solar
Hydro
Geothermal
Wind
Nuclear
How It Works
 Passive- directly using Sun’s
radiation to heat buildings.
 Active- solar cells capture Sun’s
radiation and convert it into an
alternating current (AC) or
electricity that can be use directly or
stored in a battery for later use
 Dam blocks free-flowing water
(reservoir) and allows it to pass
through a penstock; there is a
turbine at the end of the penstock
which is connected to generator
(which converts the mechanical
energy into usable electricity)
 Recall: geothermal gradient which
states that temperatures generally
increase with Earth’s depth
 Produced by Earth’s naturally
occurring heat, steam, and hot water
by bringing that heat to the surface
via some type of conductor
 Wind spins turbine blades, which in
turn rotates a shaft connected to a
generator (which converts the
mechanical energy into usable
electricity)
 Process in which heavy uranium
atoms are split (nuclear fission) in a
reactor, which releases a large
amount of thermal energy used to
heat water and create steam; the
steam is then used to turn a turbine
which is connected to a generator
(converts mechanical energy into
usable electricity)

Biofuel
Ethanol is a liquid produced by
fermenting crops such as barley,
wheat, and corn that can be blended
with gasoline to reduce
consumption of fossil fuels.
Advantages




Renewable fuel (sun)
Sunlight is free
No pollution
Can be used in a small
scale
 Renewable fuel (water)
 Free-flowing water is
free where it exists
 Reliable
 No time limitations













Renewable fuel source
Doesn’t rely on sun
No pollution aside from
bringing natural
chemicals to surface
(radon)
Can be use 24/7/365
Renewable fuel (wind)
Wind is free where it
exists
Cost-efficient once
turbines installed
Relatively low
maintenance costs
Highly efficient
Can produce large scale
electricity with small
amount of uranium
No air pollution
Cost-efficient once plant
is built
Can be used anytime
 Renewable fuel (corn)
 In some cases can be
cheaper than fossil fuels
 Burns cleaner than
fossil fuels
Disadvantages






It’s not always sunny (night)
Inefficient on cloudy days
Cells are expensive
Hard to store energy
Not great for large-scale
Passive solar not strong
enough for electricity
 Expensive to build dam
 Takes up large space
 Impacts river balance and
natural ecosystem
Location
 Where there is a lot of
sunlight (not shady)
 The closer to the equator
the better, away from
poles
 Can be used on building
rooftops
 Where there is abundant
free-flowing water
 Large river systems
 Generally warmer
climates where water
doesn’t freeze over in
colder months
Time
 When there is
sunlight
 Daylight hours
 Summer is most
ideal
 24/7/365
 Power plants are expensive
to build
 Not cost effective if not near
plate boundary
 Have to monitor natural
pollutant levels (radon)
 Near plate boundaries or
where is close proximity
to geothermal heat
 No mountains
 Hot springs
 If in right location
can be used
24/7/365






It is not always windy
Turbines are noisy
Can kill migrating birds
Turbines are expensive
Need to be maintained
Not ideal near population
 Where it is windy
 Flat rural areas (Midwest
United States)
 On large bodies of water
or near coasts
 Points of highest
elevation (mountain tops)
 Currently is costcompetitive for
electricity
production
 When there is
wind






Expensive to build plant
Radioactive waste
Can be dangerous
Strict regulations
Public perception
Nonrenewable fuel
 Near a water source
 Away from densely
populated areas, but not
too far (costs rise to
transport energy)
 Government support
 Away from earthquake or
hurricane prone areas
 24/7/365
 Currently is costcompetitive for
electricity
production

Need to surplus of ethanol –
based crops
Still does produce air
pollution




Where there is a corn or
crop surplus
Humid climates
But can be transported
anywhere like a fossil fuel


Cheaper in
harvesting seasons
(locally)
When fossil fuel
prices are high
25.3 Conservation of Energy Resources
Main Idea: Using energy efficiently reduces the consumption of nonrenewable resources.
Global Use of Energy Resources
 Petroleum is the most
widely used energy
resource worldwide
followed closely by coal
and natural gas (see right).
 Developing countries obtain 41% of their energy from a renewable resource, compared to industrialized
countries where renewable resources account for only 10% of the energy used.
o
Using renewable energy resources that are locally available conserves the fuel that would be used
to transport and process resources at a different location.
 Using a variety of energy resources rather than a single, nonrenewable energy resource can also help
conserve resources.
Energy Efficiency
Energy: the ability to do work.
Energy Efficiency: the amount of work produced compared to the amount of energy used.

Energy resources do not produce 100% of the potential work that is stored in the energy source.

Most of the electricity in the U.S. is generated by burning fossil fuels to heat water, forming steam.
o
This is an inefficient process. Approximately one-third of the energy potential within the original
fuel source can be converted into steam pressure.

Although most transportation currently relies on oil, conservation practices can help reduce dependency
on oil resources used for transportation.
o
People in metropolitan areas can improve energy efficiency by using public transportation.
o
The use of fuel-efficient vehicles also reduces the amount of petroleum resources consumed.

Increased demand for fuels requires a greater supply and results in higher costs.

If energy is used more efficiently, less energy would be needed, thus decreasing the total cost of energy.
Cogeneration: the simultaneous production of two usable forms of energy.
 While industries use one-third of all energy produced in the United States, cogeneration has allowed some
industries to increase production while reducing energy use.
Sustainable Energy
Sustainable Energy: global management of Earth’s natural resources to ensure that current and future energy
needs will be met without harming the environment.
 Global cooperation can help maintain the necessary balance between protection of the environment
and economic growth.