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Unit 5: Human/Environment Interaction
(Lessons 4 – 5)
Energy
Energy, the usable power that comes from heat, electricity, motion, etc. is used
every day. Here at school, energy is used in the lights so you can see, in the
heating and cooling so you can be comfortable, in the kitchen appliances that will
make your lunch, in the data projectors and computers that will be used in your
learning, and in the bus or car that will take you home. Energy creation and
utilization is a vital part of life on Earth and can be created from both non-renewable
and renewable natural resources.
Non-Renewable Resources
Non-renewable sources of energy are those
that we use up and cannot be replaced in
more than a few generations. Common non-
renewable energy sources include oil, coal,
natural gas, and nuclear energy. Oil, coal,
and natural gas are all fossil fuels, meaning
they were formed from the remains of once
living organisms. One major disadvantage of
using fossil fuels is that are nearly impossible
to replace. Another major disadvantage of using fossil fuels to create energy is that
they emit greenhouse gases such as carbon dioxide and methane. Greenhouse
gases are chemical compounds found in the earth’s atmosphere, which contribute to
climate change.
• Coal: Coal is the most abundant fossil fuel produced in the United States and
is relatively inexpensive to produce and convert to useful energy. About 93%
of the coal used in the United States is used for generating electricity. The rest
is used as a basic energy source in many industries including steel, cement,
and paper. Coal is mined in 25 states including Wyoming, West Virginia,
Kentucky, Pennsylvania, and Texas. Just extracting coal from the earth has
environmental impacts. Underground coal mining results in the emission of
methane, a strong greenhouse gas. In addition, a controversial mining
technique has been developed where the tops of mountains are literally
removed using explosives and mining equipment. As a result, the
environmental landscape is permanently changed. After coal is mined, it is
burned to produce energy. Burning coal produces numerous emissions that
adversely affect the environment and human health.
• Oil: Products from the fossil fuel oil
(petroleum) help us do many things. We
use them to fuel our airplanes, cars, and
trucks, to heat our homes, and to make
products like medicines and plastics.
There are about 100 countries that
produce crude oil. The graph to the right
shows the top oil-producing countries.
Despite being a top world producer, the
United States relies on imports for about
40% of the petroleum that we use. Even
though petroleum products make life
easier — finding, producing, moving, and
using them can harm the environment through air and water pollution.
• Natural gas: About 25% of energy used in the United States comes from a
fossil fuel called natural gas. Natural gas is used to produce steel, glass,
paper, clothing, brick, electricity, and as an
essential raw material for many common
products including paints, fertilizer,
plastics, antifreeze, dyes, photographic
film, medicines, and explosives. Slightly
more than half of the homes in the United
States use natural gas as their main
heating fuel. Natural gas is also used in
homes to fuel stoves, water heaters,
clothes dryers, and other household
appliances. The major consumers of
natural gas in the United States can be
seen in the pie chart on the right. Most of
the natural gas consumed in the United
States is produced here with Texas being
the largest producing state by far. Some natural gas is also imported from
Canada and shipped to the United States in pipelines. Burning natural gas for
energy results in much lower emissions of nearly all types of air pollutants and
carbon dioxide (CO2) than coal or refined petroleum products. There are,
however, environmental and safety issues with production and use of natural
gas. The exploration and development of natural gas production can greatly
affect an area's environment, wildlife, and human populations.
• Nuclear: Nuclear energy can be used to make electricity, but first the energy
must be released through nuclear fission. In nuclear fission, atoms are split
apart to form smaller atoms, releasing heat, which is used to produce
electricity. The fuel most widely used by nuclear plants is uranium, a
nonrenewable metal that is extracted from the earth through mining. Nuclear
power plants are located in 31 different states and provide about one-fifth of
the electricity in the United States. The vast majority of the uranium used in
these plants is imported from other countries. Unlike fossil fuel-fired power
plants, nuclear reactors do not produce air pollution or carbon dioxide while
operating. The main environmental concern for nuclear power is the waste
that can remain radioactive and dangerous to human health for thousands of
years. Also, although the risk of an uncontrolled nuclear reaction at a power
plant is small, such an event would result in widespread contamination of air
and water with radioactivity for hundreds of miles.
Fermi 2 Nuclear Power Plant located in Monroe County, in southeastern Michigan. http://michiganradio.org/post/dte-investigating-cause-small-fire-fermi-nuclear-plant-afternoon
Renewable Resources
Renewable sources of energy are those that will never run out or can be easily
replaced. Examples of renewable energy are solar, wind, hydropower, geothermal,
and biomass energy.
• Solar: The sun has produced energy for
billions of years. Solar energy is the sun’s
rays (solar radiation) that reach Earth.
When converted to thermal (or heat) energy,
solar energy can be used to heat water (for
use in homes, buildings, or swimming pools),
spaces (inside homes, greenhouses, and
other buildings) and fluids (to operate a
turbine to generate electricity). The main benefit of solar energy systems is
that they produce no air or water pollution and no greenhouse gases. Another
benefit is that solar radiation, in slightly varying degrees, is plentiful in every
country on Earth.
• Wind: Wind is simply air in motion. It is caused by the uneven heating of the
earth's surface by the sun. Today, wind energy is mainly used to generate
electricity. Wind is a renewable energy source because the wind will blow as
long as the sun shines. Like old-fashioned windmills, today’s wind turbines
use blades to collect the wind’s
energy. The blades are connected to
a drive shaft that turns an electric
generator to produce electricity.
Wind power plants, or wind farms, as
they are sometimes called, are
clusters of wind machines used to
produce electricity. A wind farm
usually has dozens of wind
machines scattered over a large
area. Wind is a clean source of
energy, and overall, the use of wind for energy has fewer environmental
impacts than using many other energy sources. There is still the problem of
what to do when the wind isn't blowing. At those times, other types of power
plants must be used to make electricity. Other drawbacks to wind turbines are
that some people do not like the visual impact they make on the landscape or
the sound that wind turbine blades make.
• Hydropower: Energy created
using moving water is called
hydropower. The amount of
available energy in moving water
varies. Swiftly flowing water in a
big river carries a great deal of
energy in its flow. Most dams in
the United States were built
mainly to control floods and to
help supply water for cities and
irrigation. However, a small
number of dams have been built specifically for hydropower generation.
Most hydropower is produced at large facilities built by the federal government.
While hydropower generators do not directly produce emissions of air
pollutants, hydropower dams, reservoirs, and the operation of hydropower
electric generators can affect the environment. These facilities can obstruct
fish migration or change natural water temperatures, water chemistry, and river
flow characteristics. All of these changes can affect the ecology and the
physical characteristics of the river. In addition, the construction of a
hydroelectric facility can result in the necessary relocation of people. Lastly,
greenhouse gases, carbon dioxide, and methane may also form in reservoirs
and be emitted into the atmosphere. The exact amount of greenhouse gases
produced from hydropower plant reservoirs is uncertain but may be equal to or
greater than the emissions from an equivalent amount of electricity generated
with fossil fuels.
• Geothermal: Geothermal energy is heat from within the earth. Temperatures
hotter than the sun's surface are continuously produced inside the earth by the
slow decay of radioactive particles. Deep underground, rocks and water
absorb the heat from magma, and the temperature of the rocks and water gets
hotter and hotter as you go deeper underground. People around the world use
geothermal energy to heat their homes and to produce electricity by digging
deep wells and pumping the
heated underground water or
steam to the surface. The most
active geothermal resources are
usually found along major plate
boundaries where earthquakes
and volcanoes are concentrated
like in the Pacific Ring of Fire.
The use of geothermal energy has
almost no negative impact on the
environment. Geothermal power plants do not burn fuel to generate electricity,
so their emission levels are very low. They release less than 1% of the carbon
dioxide emissions and 97% less acid rain-causing sulfur compounds than are
emitted by fossil fuel plants.
• Biomass: Biomass is organic material made from plants and animals. It
contains stored energy from the sun. Plants absorb the sun's energy in a
process called photosynthesis. The chemical energy in plants gets passed on
to animals and people who eat them. Biomass is a renewable energy source
because we can always grow
more trees and crops. Some
examples of biomass fuels are
wood, crops, manure, and some
garbage. When burned, the
chemical energy in biomass is
released as heat. Biomass fuel
can be burned to produce steam
for making electricity, or to
provide heat to industries and
homes. Burning biomass is not the only way to release its energy. Biomass
can be converted to other useable forms of energy, such as methane gas or
transportation fuels, like ethanol and biodiesel.
Using biomass for energy can have both positive and negative impacts on the
environment. For example, burning biomass may result in more or less air
pollution depending on the type of biomass and the types of fuels or energy
sources that it replaces. Liquid biofuels used in automobile engines are
considered to be carbon-neutral by many. This is because the plants used to
make biofuels (such as corn, sugarcane, and soy beans) absorb CO2 as they
grow offsetting the CO2 produced when biofuels are made and burned.
However, growing plants for biofuels is controversial because the land,
fertilizers, and energy used to grow biofuel crops could be used to grow food
crops instead.
Global Warming and Climate Change
Global warming refers to the recent and ongoing rise in global average temperature
near Earth's surface. Increasing concentrations of greenhouse gases in the
atmosphere are its main cause. Global warming has resulted in climate change, a
long-term change in the earth's climate.
Global warming is complicated, and its impact is difficult to predict. However,
scientists are gaining greater understanding about how it is affecting our planet. If
trends continue, many believe these affects will include the following:
• More intense storms will likely result from having
warmer ocean temperatures, particularly tropical
cyclones. This means that natural disasters could
become more destructive.
• Glaciers will melt as the earth’s temperatures
continue to rise. Most scientists project that,
within a matter of years, the Arctic Sea will be
completely ice-free during the summer months.
Montana’s Glacier National Park once held about
150 glaciers that were larger than 25 acres; today
there are only 25 left.
• Sea levels will rise as the glaciers continue to melt.
Many coastal areas, where roughly half of the
Earth's human population lives, will be affected.
• Flooding will occur as sea levels rise. This may lead
to destruction, displacement, and death.
• Droughts and water shortages will occur as
temperatures rise and fresh water supplies dry up.
This will affect not only the water available to drink,
but it will also affect the water available for crops
and livestock.
• Mosquito-borne diseases will escalate because
flooded areas and warmer temperatures provide the
perfect breeding ground for insects. The lives of
plants, crops, and people will be in danger.
• Natural habitats will be in peril. As sea ice
disappears, ice-dependent mammals like walruses
and polar bears struggle to survive. Coral reefs are
also very sensitive to temperature changes. Even
forests will be in danger as trees will be more likely
to be affected by insect infestations.
Scientists have high confidence
that global temperatures will
continue to rise for decades to
come, largely due to greenhouse
gasses produced by human
activities. China, the most
populated country in the world, is
the largest contributor to carbon
dioxide emissions. However,
U.S. citizens contribute more
than twice as much per capita as
those in China. Coal burning
power plants and automobiles
are the biggest causes of carbon
dioxide pollution. As indicated in the chart above, in 2011, more than 80% of our
energy consumption came from fossil fuels, the energy source most harmful to our
environment and one of the largest contributors to climate change.
Experts say that steps can be taken to reduce the pollution that is contributing to
global warming. These steps would include conserving energy, manufacturing more
efficient appliances, building cleaner cars and more modern electricity generators,
and begin relying more on clean, renewable energy sources like wind, sun, and
geothermal energy. Most people agree that we need to do something about climate
change, but they differ in the approaches they think we should take.
Some people argue that we need strong government and international action to
dramatically cut the production of greenhouse gases, slow down global warming,
and prevent, as much as possible, the damage it would otherwise do. These types
of policies can help people become less dependent on foreign sources of energy,
especially oil. While this approach is likely to hurt the oil business, it will protect the
overall economy from ecological disasters, while also creating new business
opportunities in other areas such as clean energy and “green” construction.
Other people feel that we need to focus on the areas of the world that are most
vulnerable to the effects of global warming and figure out how to help them adapt
and cope with the serious problems climate change will cause. This approach
focuses on saving lives rather than on hoping to stop global warming altogether.
A third approach is to trust that the free
market will make the necessary changes to
address the challenges of global warming
when the time is right. People who support
this approach argue that as long as it is
profitable to “go green” or develop strategies
that help communities adapt to climate
change, creative entrepreneurs will seize the
opportunity.
Which approach is the right one? Who
knows, but one thing is certain. Global
warming and climate change are happening,
and the consequences will be faced sooner if
we do nothing.