Energy - Environmental Science - page 286

Typical citizens of advanced industrialized nations each con-
sume as much energy in six months as typical citizens in de-
veloping countries consume during their entire life.
M AURICE S TRONG

13-1 EVALUATING ENERGY
RESOURCES

Science: Solar and Commercial Energy
About 99% of the energy that heats the earth
and our buildings comes from the sun; the
remaining 1% comes mostly from burning fossil
fuels.
Almost all of the energy that heats the earth and our
buildings comes from the sun at no cost to us. Without
this essentially inexhaustible solar energy ( solar capi-
tal ), the earth's average temperature would be

This chapter evaluates the use of nonrenewable fossil
fuel and nuclear power energy resources, ways to im-
prove energy efficiency, and use of renewable energy
resources. It addresses the following questions:

How should we evaluate energy resources?

■

What are the advantages and disadvantages of
conventional oil, heavy oils, natural gas, coal, and
conversion of coal to gaseous and liquid fuels?

■

240°C

400°F), and life as we know it would not exist.
This direct input of solar energy produces several
other indirect forms of renewable solar energy. Examples
include wind, falling and flowing water (hydropower),
and biomass (solar energy converted to chemical en-
ergy and stored in the chemical bonds of organic com-
pounds in trees and other plants).
Commercial energy sold in the marketplace makes
up the remaining 1% of the energy we use to supple-
ment the earth's direct input of solar energy. Most
commercial energy comes from extracting and burn-
ing nonrenewable mineral resources obtained from the
earth's crust, primarily carbon-containing fossil fu-
els—oil, natural gas, and coal (Figure 13-2).

What are the advantages and disadvantages of
conventional nuclear fission, breeder nuclear fis-
sion, and nuclear fusion?

■

How can we improve energy efficiency and what
are the advantages of doing so?

■

What are the advantages and disadvantages of us-
ing renewable energy in forms such as solar en-
ergy, flowing water, wind, biomass, geothermal en-
ergy, and hydrogen?

■

How can we make a transition to a more sustain-
able energy future?

■

KEY IDEAS
■ About 78% of the commercial energy we use
comes from nonrenewable fossil fuels. These fuels pro-
duce much of the world's air and water pollution and
add carbon dioxide to the troposphere, which can
lead to global warming.
■ The United States—the world's largest oil user—has
only 2.9% of the world's proven oil reserves and only a
small percentage of its unproven reserves. It imports
62% of its oil.
■ The nuclear power fuel cycle has a fairly low envi-
ronmental impact, an ample supply of fuel, and a very
low risk of an accident, but costs are high, radioactive
wastes must be stored safely for thousands of years,
and facilities are vulnerable to terrorist attack.
■ About 43% of the energy used in the United States
is wasted unnecessarily.
■ During this century, we will need to make a transi-
tion from dependence on nonrenewable fossil fuels to
greatly improved energy efficiency and much greater
dependence on renewable energy resources.
■ Making the transition to a more sustainable energy
future depends mainly on citizens insisting that
elected officials and businesses implement policies for
such a shift.

Global Outlook: Types of Commercial Energy
the World Depends On
About 76% of the commercial energy we use comes
from nonrenewable fossil fuels.
About 82% of the commercial energy consumed in the
world comes from nonrenewable energy resources—
76% from fossil fuels and 6% from nuclear power (Fig-
ure 13-3, left). The remaining 18% comes from renewable
energy resources—biomass (11%), hydropower (4.5%),
and a combination of geothermal, wind, and solar
energy (1.5%).
Roughly half the world's people in developing
countries burn wood and charcoal to heat their
dwellings and cook their food. This biomass energy is
renewable as long as wood supplies are not harvested
faster than they are replenished.
Unfortunately, many of these individuals face a
fuelwood shortage that is expected to worsen because
of unsustainable harvesting of fuelwood. Also, at least
2 million people die prematurely each year from
breathing particles emitted by burning wood indoors
on open fires and in poorly designed primitive stoves.

Examine and compare energy sources used in developing
and developed countries at Environmental ScienceNow.