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.