Questions and Answers of Sustainable Engineering

For the widget manufacturing system in Figure 10.12, Figure 10.12:Consider a modified case in which the plastics production process produces 1.5 kg of expanded (exp.) plastic and 0.85 kg of
Explain the direct and total requirement matrices.
Five life cycle modules involved in washing a cup in a standard size residential dishwasher are shown in Figure 10.14. Figure 10.14:For simplicity, many operations, emissions, and resources are not
What is a tiered hybrid model? Explain with an example and figure.
Inventory data for a paper towel dispenser are given in Problem 9.7. Problem 9.7:Using this information, determine the technology and environmental intervention matrices for this product. 1 paper
Consider the network shown in Figure 10.15. It consists of three sectors (nodes) and shows the monetary exchange between the sectors. The final demand and value added flows are shown as flows to and
An input-output model consists of the following flows in dollars: x11 = 10, x12 = 20, x21 = 30, x22= 10. The throughputs are x1= 50 and x2 = 40, and the emissions of CO2 from sectors 1 and 2 are 50
In its efforts toward sustainability, an American university campus is replacing paper towel dispensers in restrooms with electric hand dryers based on air drying. Another hand-drying system popular
Consider six common products: cars, shoes, laundry detergent, fleece jackets, beer, and milk, and the following five steps in their life cycles: resource extraction, manufacturing, transportation,
You wish to conduct a sustainability assessment to compare the impacts of commuting by a personal vehicle versus by car pooling. Define the goal of this study and determine the appropriate functional
A life cycle assessment of disposable cold cups conducted for Starbucks Coffee Company and NatureWorks LLC compared cups and lids made out of polypropylene (PP), polyethylene terephthalate (PET), and
Answer the following questions for assessing a polyethylene terephthalate (PET) bottle. 1. Identify the processes in the life cycle of this plastic bottle that may be the most important. Draw the
In today's globalized economy, it is common for supply chains to extend across multiple countries. Draw the process network for the following products. 1. A shirt sold in the USA says "Made in
Find the following data from the appropriate database in Table 9.3. State your assumptions, if any.Table 9.3:1. The fossil energy use and particulate matter emission to air from hauling a ton of
Explain the meaning of a scaling factor.
Define final demand.
Process 1 produces P, Q, and R. The masses of P, Q, and R are 100 kg, 20 kg, and 5 kg, respectively, and their monetary values are $1000, $100, and $20. This process emits 500 kg of CO2. Process 2
Which are the three methods that can be used to allocate emissions from a process between multiple products?
A life cycle assessment of disposable cold cups conducted for Starbucks Coffee Company and NatureWorks LLC. Compared cups and lids made out of polypropylene (PP), polyethylene terephthalate (PET),
If different allocation methods give conflicting results, what is the recommended approach?
Sustainability assessment of emerging technologies can be very useful for guiding their development in a way that prevents unintended harm. Since such technologies are often not yet implemented,
Which method should be used for uncertainty analysis if information about uncertainty is qualitative?
An integrated gasification combined cycle (IGCC) plant can convert coal and water to electricity and hydrogen. The carbon dioxide from such a process may be captured by a double-stage solvent such as
A well produces 6000 standard cubic feet (scf) of gas for every barrel (bbl) of hydrocarbon liquid. 1. Assuming a heating value of 1000 BTU/scf for gas and six million BTU/bbl for hydrocarbon
The information about some LCI modules is as follows. ∎ 1 kWh of electricity requires 0.64 kg of water, and the process emits ∎ 1.12 kg of CO2, 1.1 x 103 of S02, and 1.97 x 10- kg of NOx.
Answer the following questions using data from Table 9.2. Table 9.2:1. A company spends $10,000 per year on courier services. Determine the resulting life cycle emission of carbon dioxide and
A life cycle assessment of an office building finds the climate change impact of the building materials to be 4818 tons CO2 equivalent, of the construction to be 822 tons CO2 equivalent, of the
In a product life cycle, the emission of CO2 and the use of water depend on three variables, xi, i= 1,2,3, according to the following equations: yco2 = 100x + 11x2-7x3; YH20=22x1-x2 +50x3. The
What is a technology matrix?
Process A uses 10 m of oil and 10 kWh of electricity to produce 8 m of fuel. It emits 1.5 m of SO2. Process B uses 1 m of fuel to produce 5 kWh of electricity and emits 0.2 m of SO2. Answer the
Explain how electricity is a higher-quality resource than coal.
Consider the coal to electricity process that we studied in the previous chapter. Calculate the industrial CDP and the ecological CDP for this process and compare the results with those from energy
Explain why exergy is a common currency that flows through all systems.
A gas-electric hybrid truck has an internal combustion engine that provides 24 mpg and a battery that uses 40 kWh per 100 miles. Calculate the miles per gallon equivalent for this vehicle.
What is a unit emergy value? What are its units?
Discuss whether there is a relationship between energy quality and the power or energy density of various renewable and non-renewable resources.
Explain the emergy yield ratio. Why is its value always larger than or equal to 1?
This question is based on the debate between Professors Dale and Pimentel about "The cost of biofuels". One statement made by Professor Dale is as follows. One megajoule of coal is simply not
The supply chain of a plastic bottle involves transportation, bottle manufacturing, polymer manufacturing, and monomer manufacturing. The exergy consumed in each of the three manufacturing steps is
1,3-propanediol (PDO) is an important intermediate in the production of various plastics and fibers. It may be derived from fossil or biomass resources. Tables 14.8 and 14.9 contain information about
Data about commercial cabbage cultivation in Kenya is provided in Table 14.10. Answer the following questions. 1. Calculate the emergy of each flow and the renewability index, environmental loading
Data related to the installation and operation of a rain garden in Syracuse, New York are provided in Table 14.11. Table 14.11:The total emergy of the purchased materials is 943,006 sej. Calculate
What are the four steps in life cycle assessment?
Emissions from a life cycle include 1000 kg of CO2, 200 kg of SO2, 100 kg of NO2, and 10 kg of CH4. Convert this information to mid-point indicators.
Using the life cycle assessment results for grocery bags in Table 15.4.Table 15.4:Normalize and create the bar plot shown in Figure 15.2.Figure 15.2: Table 15.4 Mid-point indicators for different
What are the steps in life cycle impact assessment?
For the partial life cycle inventory of electricity production from natural gas given in Table 9.1: apply life cycle impact assessment to determine the mid-point and end-point indicators.Table 9.1:
What are the units of eutrophication and ecotoxicity?
Why does end-point impact assessment rely on subjective weighting factors?
The cradle-to-gate inventory of acetic acid includes the following emissions to air: 5.70E-04 kg of ammonia, 1.76E-03 kg of carbon dioxide, 3.97E-03 kg of carbon monoxide, and 4.00E-05 kg of
The life cycle inventory data for soybean oil after allocation are given in Table 15.11.Table 15.11: Answer the following questions using the data available here. Discuss the shortcomings of each
What are the advantages and disadvantages of representing life cycle impact in terms of a single indicator?
The availability of ecosystem services is essential for sustaining all activities on Earth. Compare the methods of emergy (ECEC) analysis, life cycle assessment, and water footprint analysis by
Food packaging can reduce food spoilage but also has a large environmental impact owing to the nature of the packaging materials. In an effort to reduce the environmental impact of food packaging,
Calculate the carbon footprint for manufacturing a cup made of polyethylene terephthalate using the data in Table 15.12.
Ionic liquids form a new class of solvents that are expected to be more environmentally friendly than conventional solvents owing to their low volatility and high stability. Since these solvents are
How is the goal and scope step in TES-LCA different from conventional LCA?
Describe how you may determine the service shed of the following ecosystem services: insect pollination, flood regulation, crude oil provisioning.
What is an island of sustainability?
Read the article available at http://nyti.ms/1p45jNW. Connect the concepts of economic externalities and tragedy of the commons to the issues discussed in this article. On the basis of this
Discuss in brief the relationship between the Jevons paradox and the present cultural narrative. Can the Jevons paradox be affected by changing the cultural narrative?
Explain how (a) viewing wilderness as a cursed land and (b) stripping nature of any sacrality can contribute to decisions that are not sustainable.
Discuss how environmentally beneficial farming activities would need to be communicated to conservative and to liberal farmers.
A large number of decisions about changes in land use due to the construction of large dams, long pipelines, and roads have resulted in conflicts between indigenous populations and businesses.
As an effort toward addressing plastic pollution, many cities and communities are proposing bans of plastic bags, disposable food packaging, and other products. What political challenges is such a
State the goal of a sustainability assessment of grocery sacks.
A common quandary for the environmentally conscious shopper is about the type of bag that should be used to carry groceries. Identify the process network to approximate the life cycles of grocery
What are the four steps in assessing life cycle networks?
The average projected lifespans of 60-W-equivalent incandescent, CFL, and LED bulbs are 1200 hours, 10,000 hours, and 50,000 hours. Determine the functional unit for comparing the life cycles of
Explain the concept of functional units, with the help of an example.
Determine the functional unit for comparing the life cycle impact of a textbook printed on paper versus one that is delivered electronically. Identify the most important processes in both life
Which are the three methods that can be used to determine the life cycle boundary?
Many studies identify the importance of changing global diets for addressing issues related to environmental sustainability and health. For a comparison of the life cycle impacts of different diets,
What is a cradle-to-gate life cycle boundary?
The flows in an economic input-output model are as follows: x11 = 50, x12 = 50, x21 = 30, x22=0, ƒ1= 10, ƒ2 = 25. 1. Determine the input-output model for this network. You need to derive two
Consider the economic input-output model represented by the following equations: The energy intensity of sectors 1 and 2 is 10 J/$ and 20 J/$, respectively. Calculate the total life cycle energy use
For the system in Example 10.1, Example 10.1:determine the sensitivity of the flows of crude oil, SO, and CO for producing 100 kWh of electricity. You may consider a 10 percent variation in the
Define the carbon footprint and water footprint.
An economic input-output model consists of the following flows: x11 = 50, x12 = 50, x21 = 30, x22 = 0, ƒ1 = 10, ƒ2 = 25.1. Determine the input-output model for this network. You need to derive two
Define exergy.
Large volumes of fresh water and sea water mix where rivers meet the sea. This concentration gradient could be used to do work and generate electricity. Calculate the maximum work that can be done
A hot stream provides 2 kg/s at 200 C, with specific heat 3 kcal/kg C. A cold stream is available at 30 οC and with specific heat of 2 kcal/kg οC. 1. Determine the flowrate of the cold stream
A large number of commuters walk in and out of train stations every day. The changing pressure on the floor could be utilized to generate electricity. Each weekday, 3.64 million passengers walk
Post-combustion carbon capture is increasingly being considered in power plants that burn fossil fuels such as coal or natural gas. Typical flue gas is at 40 οC and has 13 percent CO2; the remainder
Define cumulative exergy and cumulative degree of perfection.
For a light bulb, the exergy efficiency of fuel mining is 93 percent, of fuel conversion to electricity is 34 percent, and of the device is 12 percent. Calculate the cumulative degree of perfection
Define the TES-LCA absolute sustainability metric.
A watershed has a land area of 10,000 m2 and receives annual precipitation of 100 m2. Two towns occupy areas of 1000 m2 and 800 m2. Farmland occupies 6000 m2, and the remaining area is publicly
The information in Table 16.4 is for three companies that share the same service shed for air quality regulation and water provisioning ecosystem services. Within this service shed also lies 1500
Give an example of how TES-LCA can encourage ecosystem restoration.
A partial life cycle of corn ethanol accounts for the farming, ethanol production, nitrogen and phosphorus fertilizer manufacturing, and diesel production steps. The local demand and supply of CO2
What is a serviceshed?
Consider the systems shown in Figure 16.12. Figure 16.12:Answer the following questions. 1. What are the intervention, technology, ecology, and management matrices for this system? 2. The total
The NREL life cycle inventory database contains information about the manufacture of phosphate fertilizer, which quantifies the demand for the air quality regulation ecosystem service in the form of
A small water catchment has three activities nested within it, each requiring water for their operations. The water demands from the three activities are 100 m3/year, 150 m3/year, and 250 m3/year.
A land use study at a refinery in Texas finds that 10 percent of the land under consideration is covered by trees, 20 percent has no trees, 34 percent is roads, 7 percent is impervious buildings, and
Consider rice production activities in three farms located in China, India, and the USA. The runoff of nitrate fertilizer requires the ecosystem service of water quality regulation. The nitrate
A residential system uses 61.64 GJ of electricity per year for cooling during summer, in the absence of any trees around the house. If shading trees were present, they would reduce electricity
What is a desirable value of the following measures for an investment to be attractive: (a) Return on investment, (b) Payback period, (c) Discounted cash flow rate of return?
A cellulosic ethanol process is estimated to have capital costs of $15 million two years before the present, $118 million one year before the present, and $63 million in the present year. Operation

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