Energy - Environmental Science - page 307

80% (compared to 30-40% for coal-fired boilers and
nuclear power plants) and emit two-thirds less CO 2
per unit of energy produced than conventional coal-
fired boilers.
Cogeneration has been widely used in Western
Europe for years. Its use in the United States (where it
now produces 9% of the country's electricity) and
China is growing.
Another way to save energy and money in indus-
try is to replace energy-wasting electric motors, which con-
sume one-fourth of the electricity produced in the
United States. Most of these motors are inefficient be-
cause they run only at full speed with their output
throttled to match the task—somewhat like driving a
car very fast with your foot on the brake pedal. Each
year, a heavily used electric motor consumes 10 times
its purchase cost in electricity—equivalent to using
$200,000 worth of gasoline each year to fuel a $20,000
car! The costs of replacing such motors with adjustable-
speed drive motors would be paid back in about 1 year
and save an amount of energy equal to that generated
by 150 large (1,000-megawatt) power plants.
A third way to save energy is to switch from low-
efficiency incandescent lighting to higher-efficiency fluores-
cent lighting.

Solutions

Reducing Energy Waste

Prolongs fossil fuel supplies

Reduces oil imports
Very high net energy
Low cost

Reduces pollution and
environmental degradation

Buys time to phase in renewable
energy

Less need for military protection of
Middle East oil resources
Improves local economy by
reducing flow of money out to pay
for energy
Creates local jobs

Figure 13-22 Solutions: advantages of reducing energy
waste. Global improvements in energy efficiency could save the
world about $1 trillion per year—an average of $114 million per
hour! Critical thinking: which two of these advantages do you
believe are the most important?

Science: Saving Energy in Transportation
The best way to save energy in transportation is to
increase the fuel efficiency of motor vehicles.
Good news. Between 1973 and 1985, average fuel effi-
ciency for new vehicles sold in the United States rose
37% because of government-mandated corporate aver-
age fuel economy ( CAFE ) standards. Bad news. Between
1985 and 2004, the average fuel efficiency of new
cars sold in the United States leveled off or declined
slightly and in 2004 reached a 23-year low. According
to energy expert Amory Lovins, the average fuel effi-
ciency of Ford cars and trucks is now worse than
when the company started 100 years ago with the
Model A.
Fuel-efficient cars are available but account for
less than 1% of all car sales. One reason is that the in-
flation-adjusted price of gasoline today in the United
States is low (Figure 13-23 and Connections, both on
p. 308). A second reason is that two-thirds of U.S. con-
sumers prefer SUVs, pickup trucks, minivans, and
other large, inefficient vehicles. A third reason is the
failure of elected officials to raise CAFE standards
since 1985 because of opposition from automakers and
oil companies.
Suppose that Congress required the average car in
the United States get 17 kilometers per liter (40 miles
per gallon) within 10 years. According to energy ana-
lysts, this change would cut gasoline consumption in
half, save more than three times the amount of oil in

■ In a coal-burning power plant, two-thirds of the en-
ergy released by burning coal ends up as waste heat in
the environment.

Energy experts call for us to replace these devices or
greatly improve their energy efficiency over the next
few decades.
According to a 2004 study by David Pimentel and
other scientists, the U.S. government could within a
decade implement energy conservation and efficiency
measures that would reduce current energy consump-
tion by one-third and save consumers $438 billion per
year.

Science: Saving Energy and Money
in Industry
Industries can save energy and money by producing
both heat and electricity from an energy source and by
using more energy-efficient electric motors and
lighting.
Some industries save energy and money by using co-
generation, or combined heat and power (CHP) systems.
In such a system, two useful forms of energy (such as
steam and electricity) are produced from the same fuel
source. These systems have an efficiency as high as