Industrial Ecology and Sustainable Engineering
T.E. Graedel and B.R. Allenby
EXERCISES
ANSWER KEY
CHAPTER 1
1.1 In 1983, the birthrate in Ireland was 19.0 per 1000 population per year and the death
rate, immigration rate, and emigration rate (same units) were 9.3, 2.7, and 11.5,
respectively. Compute the overall rate of population change.
R=[19.0 – 9.3] + [2.7 – 11.5] = 9.7 – 8.8 = 0.9
1.2 If the rate of population change for Ireland were to be stable from 1990 to 2020 at the
rate computed in the above problem, compute the 2020 population. (The 1990 population
was 3.72 million.)
P=3.7 e.0009 (30) = 3.80 million
1.3 Using the “master equation,” the “Units of Measurement” section in the Appendix,
and the following data, compute the 2007 GDP/capita and equivalent CO2 emissions per
equivalent US dollar of GDP for each country shown in the following table:
2007 Master Equation Data for Five Countries @
Country Population* GDP ** CO2 Emissions+
Brazil 188 621 106
China 1314 2512 1665
India 1095 796 338
Nigeria 132 83 114
United States 298 13220 1709
.
* Millions ** Billion of US dollars + Teragrams C/yr
,Solution:
Country GDP/capita ECO2/dollar of GDP
(in g C/yr)
Brasil 3303 171
China 1912 663
India 727 425
Nigeria 629 1370
United States 44360 129
1.4 Trends in population, GNP, and technology are estimated periodically by many
institutions. Using the typical trend predictions below, compute the equivalent CO2
anticipated for the years 2010 and 2025 for the five countries. Graph the answers,
together with information from 2007 (previous problem), on an ECO2 vs. year plot.
Comment on the results.
Master Equation Predicted Data for Five Countries @
Country Population * GNP growth (%/yr) Decrease in
2000 2025 1990-2000 2000-2025 ECO2/GNP(%/yr)
Brazil 175 240 3.6 2.8 0.5
China 1290 1600 5.5 4.0 1.0
India 990 1425 4.7 3.7 0.2
Nigeria 148 250 3.2 2.4 0.1
United States 270 307 2.4 1.7 0.7
* Millions
@ Data for this table were drawn primarily from J.T. Houghton, B.A. Callander, and S.K.
Varney, Climate Change 1992, Cambridge, U.K.: Cambridge University Press, 1992.
Solution:
The easiest way to find the solution is to use the following formula (taking ECO2/GDP
numbers from the previous question and dividing by 1012 at the end to put it into Tg):
(ECO2/GDP2007)((1-((%decrease in ECO2/GNP)/100))years)(GDP2007*(1+(%increase GDP)/100)years/(1012)
Example for Brazil in 2010:
171*(.995)3*(621*109)*(1.028)3/1012=114
The quickest way to do the computation is to take the 2007 ECO2 values and decrease
them by the percentages given.
2
,Country 2007: ECO2 (Tg/yr) 2010: ECO2 (Tg/yr) 2025: ECO2 (Tg/yr)
Brazil 106 114 160
China 1665 1818 2816
India 338 375 628
Nigeria 114 122 171
United States 1709 1756 2036
As shown in the chart, although China has the largest rate of decrease in ECO2/dollar
GDP, it also has the largest rate of growth for GDP, so it will overtake the US as the
largest emitter before 2010.
CHAPTER 2
2.1 Section 2.2 proposes that 25-50 years is the best choice for a sustainability planning
time scale. Do you agree? Explain.
The response could involve discussion of human adult lifetime, scales of carbon and
climate cycles, the multifaceted nature of the transition, monitoring of change, or
development of technology. It may also address differences in time scale between
planning for “weak” or “strong” sustainability.
2.2 Use the information in Table 2.1 to estimate how much zinc could be used in a
“sustainable” automobile. Clearly show your reasoning.
Solution Notes: The key here is obviously to use the Sustainable Rate of Use of 1.5
kg/(person-year) from Table 2.1. The answer should consider the replacement rate of
cars and consumption of zinc in other forms (doorknobs, etc). The final calculation
should be something similar to:
(1.5–[other uses])*[number of years car is expected to last]=[zinc estimate in kg]
2.3 Consider the quantitative sustainability example of greenhouse gases in Section 2.3.3.
Discuss the options for allocating the allowable CO2 emissions, together with the benefits
and problems of the options.
3
, The response should address the target of 1 metric ton per person as the sustainability
goal. Allocation may be made to transportation, heating, electricity, product production,
etc. The response should address these issues and the challenges associated with meeting
the carbon limit required for sustainability. Alternative transportation and energy
schemes should be considered.
2.4 Section 2.4.1 defines four “example” Grand Objectives for sustainability. Do you
agree that this is the ideal set? If so, why? If not, present and discuss alternatives.
The response should mention each of the four presented Grand Objectives for
sustainability: (1) Maintaining the existence of the human species, (2) Maintaining the
capacity for sustainable development and the stability of human systems, (3) Maintaining
the diversity of life, and (4) Maintaining the aesthetic richness of the planet. Responses
should address whether or not these are generally accepted issues of universal importance
and whether or not societal consensus could be reached.
CHAPTER 3
3.1 Choose a room of your apartment, dormitory, or house. Conduct an inventory of the
physical items or “artifacts” in the room. Divide them into four categories: (1) The
artifact is necessary for survival; (2) The function performed by the article is necessary,
but the artifact represents unnecessary environmental impact (e.g., clothes may be
necessary, but a fur coat or ten pairs of shoes may not be); (3) The artifact is unnecessary
for survival but is culturally required; (4) The artifact is both physically and culturally
unnecessary (albeit probably desirable, or it wouldn’t be there). Can you extrapolate this
result to your general consumption patterns? Based on these results, what percentage of
your consumption represents unnecessary environmental impact?
The response should categorize student possessions into the four categories. Based on
the student response, a percentage of consumption based on unnecessary environmental
impact should be given.
Example Solution:
Category 1 Category 2 Category 3 Category 4
Boots Extra pairs of shoesDress shoes Earrings
Blanket Extra pairs of sheets
Pillow Throw Pillows
Canteen Extra plates Silverware Slow-cooker
Winter coat Extra clothes Books Wall decorations
Desk Rug
Computer Television
Unnecessary environmental impact is about 50% of my consumption.
3.2 Technology brings benefits, such as food, home heating, and medications. It also
brings potential problems, such as air pollution and ecosystem disruption. Considering
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