ENERGY, ENVIRONMENT, AND CLIMATE, Second Edition
CHAPTER 1: A Changing Planet
QUESTIONS
1.) Life has changed Earth’s atmosphere.
2.) In the first few hundred million years after the planet’s formation, Earth’s active geology and
bombardment from solar system debris eradicated any evidence of early life.
3.) Oxygen is highly reactive.
4.) Fuels (such as oil or coal) store energy. Flows (such as sunlight) deliver streams of energy.
5.) Volcanoes emitted CO2 (carbon dioxide).
6.) Higher standards of living and greater education, which are associated with higher energy
consumption, tend to enable and encourage people to choose smaller families.
7.) In 1988, more people were reproducing.
EXERCISES
1.) Solar radiation intensity S = 1,364 W/m2 = power/area. The power is the rate at which solar
energy arrives at Earth.
The effective absorbing area of Earth is that of a disk of radius RE = 6.37 × 106 m:
area = πR 2 = π ( 6.37 ×106 m ) = 1.27 × 1014 m 2
2
Therefore, power = S × area = 1.74×1017 W ≈ 170 PW
2.) From Figure 1.8, geothermal energy provides 0.025% of Earth’s total power and solar energy
provides 99.98% of Earth’s total power.
solar power
geothermal power = 0.025% total power = 0.025% ⋅
99.98%
1.74 × 1017 W
geothermal power = 0.025% ⋅ = 4.3 × 1013 W = 43 TW
99.98%
© 2012 by W. W. Norton & Company, Inc.— pg. 1
,Because the Sun’s power provides nearly 100% of Earth’s total power, we could just as well
have approximated this as
geothermal power = 0.025% × 1.7 × 1017 W = 4.3 × 1013 W .
3.) Let P0 = the initial population and P(t) = population at a later time, t. As long as we look at
population increases over short time periods (just a year), we can approximate the population
growth as linear: P(t) = P0 + m × t, where the growth rate in people per year, m, is proportional
to the percentage growth rate, g, and to the initial population: m = P0 × g.
The population grows each year by approximately ΔP = P(t) − P0 = m × t = g × P0 × t,
where t = 1 year.
1965: P0 = 3.4 billion people, g = 2% per year. Population grows this year by approximately ΔP
= g × P0 × t = 3.4 billion people × 2%/y × 1 y = 68 million people.
1985: P0 = 4.9 billion people, g = 1.7% per year. Population grows this year by approximately
ΔP = g × P0 × t = 4.9 billion people × 1.7%/y × 1 y = 83 million people.
2000: P0 = 6.1 billion people, g = 1.2% per year. Population grows this year by approximately
ΔP = g × P0 × t = 6.1 billion people × 1.2%/y × 1 y = 73 million people.
Although there were more people in 2000, the growth rate was lower, so the population grew by
a smaller number than in 1985.
4.) For population growth over a longer period of time, we need to consider cumulative effects
from year to year; the growth is no longer linear. A constant growth rate results in exponential
growth: P(t) = P0(1+g)t.
2012: Initial population P0 = 7 billion people, growth rate g = 1.1% per year.
To find the population in 2050, solve for P(t) where t = 2050 − 2012 = 38 years:
P(t) = 7*(1.01)38 = 10.6 billion people
⎛ total fossil and nuclear energy ⎞
⎜ ⎟ = 0.008%
5.) ⎝ flow to Earth's surface ⎠
solar power = 0.008% × 1.7 × 1017 W ≈ 1013 W = 10 TW
ARGUE YOUR CASE
1.) The natural flows have been in equilibrium. The “human uses” flow, although small, has
significantly disrupted the equilibrium of the Earth system.
© 2012 by W. W. Norton & Company, Inc.— pg. 2
,2.) Water power is fundamentally driven by solar radiation, which evaporates water and drives
the hydrologic cycle.
© 2012 by W. W. Norton & Company, Inc.— pg. 3
, ENERGY, ENVIRONMENT, AND CLIMATE, Second Edition
CHAPTER 2: High-Energy Society
QUESTIONS
1.) Megawatts are not energy units—they measure power, or the rate of energy use. The
newspaper editor should strike the phrase “of energy each hour” to correct the statement.
2.) Efficiencies, economies of scale, and the inaccessibility of the technologies to most people
worldwide, among other things, might account for the apparent discrepancy.
3.) Laptop charger: AC input (120 V × 1.5 A)/2 = 90 W, DC output 20 V × 2.3 A = 46 W
Electric kettle: 1500 W
Blender: 450 W (maximum)
Refrigerator: (115 VAC × 7.1 A)/2 = 409 W
Freezer: (115 VAC × 5 A)/2 = 288 W
4.) Energy intensity (Fig. 2.7). Although Egyptians use less energy and make less money than
U.S. Americans, Egypt’s energy use and GDP have about the same ratio as that of the United
States
5.) No. If 300 million Americans need the equivalent of 100 energy servants each, that requires
at least 30 billion people to supply energy. Only about 7 billion people live on the planet, and
they are not our energy servants.
6.) Japan is more compact than the United States, and has a more efficient transportation system.
Ghana is poorer, and has fewer developed commercial and industrial sectors, than the United
States or Japan.
7.) Spending billions of dollars to try to clean up a blowout of a deep-water oil drilling platform
in the Gulf of Mexico, for example, could increase the GDP, whereas the accident could decrease
the quality of life for countless citizens (and end life for some).
EXERCISES
1.) Production of 1 kW = 1,000 watts would require 10 energy servants producing 100 watts
each. To get a total of 1 kWh, I’d have to hire all the energy servants for an hour, at a cost of 10
× $8 = $80. That’s a factor of $80/$0.10 = 800 more than the typical cost for a kilowatt-hour.
2.) To make the energy servants’ power competitive with conventionally produced electrical
power, I’d have to pay them 1/800 what I paid them in Exercise 1. Their hourly wage would be
just $8/800 = 1¢ per hour.
© 2012 by W. W. Norton & Company, Inc. — pg. 1
CHAPTER 1: A Changing Planet
QUESTIONS
1.) Life has changed Earth’s atmosphere.
2.) In the first few hundred million years after the planet’s formation, Earth’s active geology and
bombardment from solar system debris eradicated any evidence of early life.
3.) Oxygen is highly reactive.
4.) Fuels (such as oil or coal) store energy. Flows (such as sunlight) deliver streams of energy.
5.) Volcanoes emitted CO2 (carbon dioxide).
6.) Higher standards of living and greater education, which are associated with higher energy
consumption, tend to enable and encourage people to choose smaller families.
7.) In 1988, more people were reproducing.
EXERCISES
1.) Solar radiation intensity S = 1,364 W/m2 = power/area. The power is the rate at which solar
energy arrives at Earth.
The effective absorbing area of Earth is that of a disk of radius RE = 6.37 × 106 m:
area = πR 2 = π ( 6.37 ×106 m ) = 1.27 × 1014 m 2
2
Therefore, power = S × area = 1.74×1017 W ≈ 170 PW
2.) From Figure 1.8, geothermal energy provides 0.025% of Earth’s total power and solar energy
provides 99.98% of Earth’s total power.
solar power
geothermal power = 0.025% total power = 0.025% ⋅
99.98%
1.74 × 1017 W
geothermal power = 0.025% ⋅ = 4.3 × 1013 W = 43 TW
99.98%
© 2012 by W. W. Norton & Company, Inc.— pg. 1
,Because the Sun’s power provides nearly 100% of Earth’s total power, we could just as well
have approximated this as
geothermal power = 0.025% × 1.7 × 1017 W = 4.3 × 1013 W .
3.) Let P0 = the initial population and P(t) = population at a later time, t. As long as we look at
population increases over short time periods (just a year), we can approximate the population
growth as linear: P(t) = P0 + m × t, where the growth rate in people per year, m, is proportional
to the percentage growth rate, g, and to the initial population: m = P0 × g.
The population grows each year by approximately ΔP = P(t) − P0 = m × t = g × P0 × t,
where t = 1 year.
1965: P0 = 3.4 billion people, g = 2% per year. Population grows this year by approximately ΔP
= g × P0 × t = 3.4 billion people × 2%/y × 1 y = 68 million people.
1985: P0 = 4.9 billion people, g = 1.7% per year. Population grows this year by approximately
ΔP = g × P0 × t = 4.9 billion people × 1.7%/y × 1 y = 83 million people.
2000: P0 = 6.1 billion people, g = 1.2% per year. Population grows this year by approximately
ΔP = g × P0 × t = 6.1 billion people × 1.2%/y × 1 y = 73 million people.
Although there were more people in 2000, the growth rate was lower, so the population grew by
a smaller number than in 1985.
4.) For population growth over a longer period of time, we need to consider cumulative effects
from year to year; the growth is no longer linear. A constant growth rate results in exponential
growth: P(t) = P0(1+g)t.
2012: Initial population P0 = 7 billion people, growth rate g = 1.1% per year.
To find the population in 2050, solve for P(t) where t = 2050 − 2012 = 38 years:
P(t) = 7*(1.01)38 = 10.6 billion people
⎛ total fossil and nuclear energy ⎞
⎜ ⎟ = 0.008%
5.) ⎝ flow to Earth's surface ⎠
solar power = 0.008% × 1.7 × 1017 W ≈ 1013 W = 10 TW
ARGUE YOUR CASE
1.) The natural flows have been in equilibrium. The “human uses” flow, although small, has
significantly disrupted the equilibrium of the Earth system.
© 2012 by W. W. Norton & Company, Inc.— pg. 2
,2.) Water power is fundamentally driven by solar radiation, which evaporates water and drives
the hydrologic cycle.
© 2012 by W. W. Norton & Company, Inc.— pg. 3
, ENERGY, ENVIRONMENT, AND CLIMATE, Second Edition
CHAPTER 2: High-Energy Society
QUESTIONS
1.) Megawatts are not energy units—they measure power, or the rate of energy use. The
newspaper editor should strike the phrase “of energy each hour” to correct the statement.
2.) Efficiencies, economies of scale, and the inaccessibility of the technologies to most people
worldwide, among other things, might account for the apparent discrepancy.
3.) Laptop charger: AC input (120 V × 1.5 A)/2 = 90 W, DC output 20 V × 2.3 A = 46 W
Electric kettle: 1500 W
Blender: 450 W (maximum)
Refrigerator: (115 VAC × 7.1 A)/2 = 409 W
Freezer: (115 VAC × 5 A)/2 = 288 W
4.) Energy intensity (Fig. 2.7). Although Egyptians use less energy and make less money than
U.S. Americans, Egypt’s energy use and GDP have about the same ratio as that of the United
States
5.) No. If 300 million Americans need the equivalent of 100 energy servants each, that requires
at least 30 billion people to supply energy. Only about 7 billion people live on the planet, and
they are not our energy servants.
6.) Japan is more compact than the United States, and has a more efficient transportation system.
Ghana is poorer, and has fewer developed commercial and industrial sectors, than the United
States or Japan.
7.) Spending billions of dollars to try to clean up a blowout of a deep-water oil drilling platform
in the Gulf of Mexico, for example, could increase the GDP, whereas the accident could decrease
the quality of life for countless citizens (and end life for some).
EXERCISES
1.) Production of 1 kW = 1,000 watts would require 10 energy servants producing 100 watts
each. To get a total of 1 kWh, I’d have to hire all the energy servants for an hour, at a cost of 10
× $8 = $80. That’s a factor of $80/$0.10 = 800 more than the typical cost for a kilowatt-hour.
2.) To make the energy servants’ power competitive with conventionally produced electrical
power, I’d have to pay them 1/800 what I paid them in Exercise 1. Their hourly wage would be
just $8/800 = 1¢ per hour.
© 2012 by W. W. Norton & Company, Inc. — pg. 1
