Questions and Answers of Sustainable Engineering

If the sea power plant described in Problem 11.5 is to deliver power at $\$ 8 / 10^{6} \mathrm{Btu}$, estimate the maximum permissible cost of the condenser and evaporator heat-exchanger surface in
On February 2006, President George W. Bush said, "All of a sudden, you know, we may be in the energy business by being able to grow grass on the ranch and have it harvested and converted into
A BMW hydrogen car uses $2.5 \mathrm{kWh} / \mathrm{km}$. Compare this performance with that of an average U.S. car that is able to get $22 \mathrm{mpg}$ of gasoline.
From the information supplied in the following text, estimate the percentage of the total land area in the lower 48 states that would have to be used to replace all of the gasoline currently used for
The combustion of ethanol goes according to the following equation:\[ \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}+\ldots \mathrm{O}_{2} \rightarrow \ldots \mathrm{CO}_{2}+\ldots \mathrm{H}_{2}
An automobile storage battery with an open circuit voltage of $12.8 \mathrm{~V}$ is rated at $260 \mathrm{~A} / \mathrm{h}$. If the internal resistance of the battery is $0.2 \Omega$, estimate
Make a preliminary design for the power train of a hydrogen/oxygen fuel cell-powered automobile. Provide a system description with preliminary design estimates of the power and fuel supply
Explain the difference in operation between HEVs with parallel and series designs.
The hallways of a three-story building in Denver, Colorado, use 600 lights per floor, and each light is an incandescent bulb rated at $60 \mathrm{~W}$.a. Estimate the amount of energy that could be
On May 27, 2009, U.S. Senator Lamar Alexander proposed to build 100 new nuclear power plants in 20 years "for a rebirth of industrial America while we figure out renewable electricity." In his talk,
Since meat is higher on the food chain than grains, the more calories you get from meat, the more agricultural land you use. Using the arable land area in your state and data from [30] (which
If $10 \%$ of your state would be covered with PV collectors, estimate the power produced in $\mathrm{kWh} /$ day per capita on average. If $10 \%$ of the people in your state had to drive
Assuming that a heat pump has a coefficient of performance equal to 4, how much heat could this device deliver to the interior of a building with $1 \mathrm{kWh}$ of electricity?
If there were a carbon tax of $\$ 250 /$ ton of $\mathrm{CO}_{2}$ on fossil fuels, estimate the increase in the price of a barrel of oil.
In 2009, the administration of President Obama instituted a so-called Cash for Clunkers program. You are to evaluate the effectiveness of the program, which was intended to stimulate the economy and
While completing your homework, imagine the study space you are using employs a space heater with a rating of $30 \mathrm{~kW}$, a refrigerator (for snacks) that is rated for $5 \mathrm{~kW}$,
In 2009, a group of environmentalists approached the Boulder City Council with a request to deny an application to continue operating the local coal-fired $200 \mathrm{MW}$ power plant in order to
A large nuclear power plant has a rated capacity of $1 \mathrm{GW}$ electric. Its actual output is estimated to average about $80 \%$ of capacity due to the need for maintenance and imperfect
The yearly average solar flux incident on a horizontal surface in the United States is about $180 \mathrm{~W} / \mathrm{m}^{2}$. The average total energy demand in the United States is
Calculate the doubling time for annual percentage increases of $2 \%$ and $10 \%$, assuming an exponential growth function.
In 2011, the United Nations announced that the human population reached 7 billion and was increasing at approximately $1.5 \%$. Estimate the doubling time of the human population and then estimate
Experts claim that there is enough coal left for at least another 400 years at current rates of consumption. Estimate how long the coal would last if its annual usage rate increase by $5 \%$ and by
The doubling time of any quantity $n$ is related to the continuous growth rate $R_{\text {cont }}$ by the relation $2=\exp n R_{\text {cont }}$. Derive an expression for $n$ in terms of the
What is the present value of a $\$ 10,000$ payment in 2015 if the discount rate is $7 \%$ ?
Repeat the previous problem in constant dollars for the $\$ 10,000$ payment if the inflation rate is $4 \% /$ year.Problem 2.2What is the present value of a $\$ 10,000$ payment in 2015 if the
Calculate the annual payments for a solar system whose initial extra cost is $\$ 10,000$. Assume that the interest rate is $8 \%$ and the mortgage term is 15 years.
Assuming that the price of fuel is $\$ 5.00 / \mathrm{GJ}$ and is increasing at a rate of $4 \% /$ year while the discount rate is $6 \%$, calculate the equivalent levelized price over 20 years.
A home buyer obtains a mortgage of $\$ 100,000$ at an interest rate of $8 \%$ over 20 years. Estimate the annual payments to repay this loan.
A rooftop solar hot water heater with collector areas of $8 \mathrm{~m}^{2}$ and storage of $640 \mathrm{~L}$ is installed in Phoenix, Arizona, on a house that uses $160 \mathrm{~L} /$ day of
Repeat the previous problem, but assume that the cost of installation is to be repaid at $7 \%$ interest over 15 years and that the electricity costs escalate at $10 \%$ per year. Compare the NPV
Repeat the previous problem, but assume that the cost of the equipment is reduced from a government grant by $20 \%$.Problem 2.8Repeat the previous problem, but assume that the cost of installation
Compare the capital costs and the levelized costs of operation for a $1000 \mathrm{MW}$ nuclear power plant and a 1000 MW PV system constructed in the Mojave desert in California. The PV system is
A solar system is to be installed in Phoenix, Arizona. The estimated amounts of energy from the system as a function of collector area are shown in the following tabulation. If the solar system costs
Calculate and tabulate the annual cash flows associated with a solar system for a 10 year period of analysis if the initial solar cost is $\$ 6000$ and if Interest rate $=9 \%$Power cost \(=\$ 30
If the initial extra cost of a solar system is $\$ 5,000$, what are the annual payments of a self-amortization loan if the interest rate is $12 \%$, the inflation rate is $4 \%$, and the
A factory uses 700.40 $\mathrm{W}$ standard fluorescent lamps for its lighting. The lamps are to be replaced by 34/W high-efficiency lamps that can operate on the existing standard ballasts. The
The hallways of a university are lit by 40 fluorescent lights, each containing two lamps rated at $60 \mathrm{~W}$ each. The lights are on all day and night during the year, but the building is
While completing this homework, imagine the study space you are using employs a space heater with a rating of $30 \mathrm{~kW}$, a refrigerator (for snacks) that is rated for $5 \mathrm{~kW}$,
A residential size WT has a diameter of 1 meter. Due to the size, its efficiency is only $25 \%$ of the Betz limit. What is the expected power output at a wind speed of 20 miles per hour? Assume
You have assembled a modern three-bladed upwind WT with a rotor radius of $5 \mathrm{~m}$ at sea level where the density is $1.225 \mathrm{~kg} / \mathrm{m}^{3}$.a. If the wind is blowing at an
An investor comes to you and tells you that a company wants to invest in a new turbine design with the following performance characteristics:$112 \mathrm{~m}$ rotor diameter\(13 \mathrm{~m} /
Weibull distribution: From an analysis of wind speed data (hourly interval average, taken over a 1 year period), the Weibull parameters are determined to be $c=6 \mathrm{~m} / \mathrm{s}$ and
Given a WT with the following parameters, calculate the annual energy production assuming a Rayleigh PDF:$C_{p}=C_{p \max }=0.40\left(C_{p}\right.$ value assumed maximum and constant for all wind
(a) What is the COE for a turbine with the following assumptions: 5 MW rating $31 \%$ capacity factor $\$ 1250 / \mathrm{kW}$ turbine cost $\$ 91,000$ operations and maintenance cost/year Fixed
Power deficit inside wind farms-Barthelmie et al. [59], present results of modeling the behavior of WT wakes in order to improve power output predictions. The following figure shows the predicted
Wisconsin produced 13,260,000 bushels ( $25.4 \mathrm{~kg}$ per bushel) of oats on 195,000 ac ( $4046.85 \mathrm{~m}^{2}$ per acre) of land. What is the corresponding yield of oat residue in
Use the USDA Quick Stats service (http://quickstats.nass.usda.gov//) to compare the 2009 oat yields between New York and California. What additional land would California require to meet the same
We can estimate future crop yields using the exponential growth formula\[ \begin{equation*} \text { Yield }(t)=\text { Yield }_{0} e^{k t} \tag{4.36} \end{equation*} \]where $k$ is the growth
The U.S. total land area is almost $9,307,800 \mathrm{~km}^{2}$. Thirty percent of the land is forestland. How much above-ground biomass is available in the U.S. forestland assuming a \(15,240
A common assumption for biorefinery capacities is $2000 \mathrm{Mg} /$ day of feedstock input capacity. What is the land area required to grow this quantity of biomass from corn stover with land
Given the enthalpy of formation for food waste to be $-394.7 \mathrm{MJ} / \mathrm{kmol}$, use the combustion reaction from Equation 4.11 to calculate its HHV (assume that the molecular formula is
Solar irradiation in parts of California exceeds $9 \mathrm{kWh} / \mathrm{m}^{2} /$ day ( 32 million MJ $/ \mathrm{km}^{2} /$ day). What are theoretical maximum C3 and C4 biomass energy yields
How many people can Hawaii feed? Different diets require different energy inputs. Since meat is higher in the food chain than grains, the more calories you get from meat, the more agricultural land
A gasifier can convert $1 \mathrm{~kg}$ of wood ( $19.5 \mathrm{MJ} / \mathrm{kg}$ ) into $1.5 \mathrm{~m}^{3}$ of syngas (5.2 MJ/m³). If we define energy conversion efficiency as the ratio of
A lactating cow can produce more than $60 \mathrm{~kg}$ of manure (about $7 \mathrm{MJ} / \mathrm{kg}$ on a dry basis) per day. What is the energy efficiency of converting cow manure to biogas if
Gasification uses an oxygen-to-fuel ratio that is $25 \%$ of the required oxygen for complete combustion. What is the amount of oxygen required to gasify $1 \mathrm{~kg}$ of wood
Steam gasification employs steam as the oxygen carrier. How much steam would be needed to gasify $1 \mathrm{~kg}$ of wood $\left(\mathrm{CH}_{1.4} \mathrm{O}_{0.66}\right)$ ?
How much air is needed to fully combust fuel oil $\left(\mathrm{CH}_{1.67} \mathrm{O}_{0.006} \mathrm{~N}_{0.005} \mathrm{~S}_{0.002}\right)$ if $25 \%$ excess air is required?
Calculate the energy conversion efficiency of biomass to gasification products assuming the yields and energy contents from Table 4.8.Table 4.8 Biomass Gasification Product Distribution and Energy
In 2005, California had almost 440 MW of coal power-generating capacity. What amount of biomass would be required to produce the same amount of electricity? Assume a biomass heating value of \(17
Assuming a chain growth probability of 0.8, calculate the mole yields for hydrocarbons with 1-24 carbon atoms using the ASF distribution. How does this distribution compare to that of a 0.9 chain
Calculate the heat of reaction for ethanol (heat of formation $-277.7 \mathrm{MJ} / \mathrm{kmol}$ ) synthesis with the mixed-alcohol process and with the methanol (heat of formation -238.4
Assuming nominal annual yields of $700,000,5,500,000$, and $3,800,000 \mathrm{~kg} / \mathrm{km}^{2}$ for corn grain, sugar cane, and sweet sorghum respectively, which conversion pathway is the
A group proposes a 2000 barrel-per-day ethanol output biorefinery using Jerusalem artichokes. What is the daily feedstock requirement for this biorefinery? What is the minimum amount of land required
If the yield of bio-oil to liquid fuels (gasoline- and diesel-like fuels) is $42 \mathrm{wt} . \%$, what is the overall energy efficiency? Use the values in Table 4.12 for energy content and
How many liters of bio-oil can be generated with Iowa's 2009 corn stover yield? Use appropriate data from Quick Stats, a $65 \mathrm{wt} . \%$ yield of bio-oil from corn stover, and a bio-oil
Using an ethanol fuel content of 21.2 MJ/L and TTW efficiency of 3.08 MJ per $\mathrm{km}$, calculate the theoretical travel distance (units of $\mathrm{km}^{2}$ per $\mathrm{km}^{2}$ of land)
Assuming a $10 \%$ improvement in the production of $\mathrm{H}_{2}$ from coal, what is the new WTW efficiency for a $\mathrm{H}_{2}$ ICE and what is the reduction in $\mathrm{CO}_{2}$
Calculate the declination, the zenith angle, and the azimuth angle of the sun for New York City (latitude $40.77^{\circ} \mathrm{N}$ ) on October 1 at 2:00 p.m. solar time.
A solar energy system in Gainesville, Florida, requires two rows of collectors facing south and tilted at a fixed $30^{\circ}$ angle. Find the minimum normalized distance at which the second row
Find the sunrise and sunset times for a location of your choice on September 1.
Construct a table of hourly sun angles for the 15th day of each month for a location of your choice. Also show the sunrise and sunset times for those days.
Determine the following for a south-facing surface at $30^{\circ}$ slope in Gainesville, Florida (latitude $=29.68^{\circ} \mathrm{N}$, longitude $=82.27^{\circ} \mathrm{W}$ ) on September 21
Prepare shadow maps for point $\mathrm{P}$ on the sun-path diagrams for $35^{\circ} \mathrm{N}$ and $40^{\circ} \mathrm{N}$ for the following three geometries shown in a, b, and c. Determine
Repeat Problem 5.8c if the surface containing point P faces due west instead of due south for a $40^{\circ} \mathrm{N}$ location.
Calculate the incidence angle at noon and 9 a.m. on a fixed flat-plate collector located at $40^{\circ} \mathrm{N}$ latitude and tilted $70^{\circ}$ up from the horizontal. Find $i$ for June 21
a. If the surface in Problem 5.10 faces $\mathrm{S} 45^{\circ} \mathrm{E}$, what are the incidence angles?b. If the collector in Problem 5.10 has a cylindrical surface, what are the incidence
Using a one-term Fourier cosine series, develop an empirical equation for solar declination as a function of day number counted from January 1 (see Table 5.1 and Figure 5.7).Figure 5.7Table 5.1
Derive an equation for the lines of constant declination in a sun-path diagram, for example, Figure 5.10d. Check your equation by plotting a few declination lines on a piece of polar coordinate graph
At what time does the sun set in Calcutta $\left(23^{\circ} \mathrm{N}\right)$ on May 1 and December 1?
What is the true solar time in Sheridan, Wyoming $\left(107^{\circ} \mathrm{W}\right)$, at 10:00 a.m. Mountain Daylight Time on June 10? What is the true solar time at 10:00 a.m. Mountain Standard
Using the Angström-Page method, calculate the average horizontal insolation in Hamburg in May and in October with $\overline{\text { PS }} 40 \%$ and $60 \%$, respectively.
Predict the hourly beam and diffuse radiation on a horizontal surface for Denver $\left(40^{\circ} \mathrm{N}\right)$ on September 9 at 9:30 a.m. on a clear day.
Derive an expression for the minimum allowable distance between east-west rows of solar collectors that will assure no shading of one row by the row immediately to the south. Use the law of sines and
Using the $\bar{H}_{h}$ data calculated in Example 5.7 in place of the long-term measured data for the North Central Sahara Desert at latitude $25^{\circ} \mathrm{N}$, find the monthly averaged
Ethanol is a required additive in gasoline in the USA and many other countries. The main steps in producing ethanol from corn include farming to grow corn and the manufacturing step in which corn
This problem utilizes the process model in Problem 10.1 and the EEIO model in Problem 10.8. Develop a hybrid model to determine the life cycle SO2 emission for producing 1000 kWh of electricity.Data
Consider the economic input-output system shown in Problem 10.6. Suppose the energy consumptions of the three sectors are t1 = 100 MJ/$, t2 = 500 MJ/$, and t3 = 200 MJ/$. 1. Calculate the life cycle
Visit the web pages of some corporations that describe their efforts toward sustainable development. Are these efforts addressing all the requirements for sustainability presented in Section
1. Explain why Milton Friedman recommended that companies should not try to reduce emissions beyond the minimum regulatory requirement. What must he have assumed about negative externalities due to
For the environmentally extended input-output data given in Table 14.7, answer the questions that follow given one million dollars of final demand from sector 2. 1. Calculate the monetary throughput
Fill in the blanks. "Eco-efficiency aims to create more ______________with less_________________."
A history of chlorofluorocarbon (CFC) compounds and the ozone hole is provided in Chapters 2 and 5.history of chlorofluorocarbon (CFC):What role did the cultural narrative and political aspects play
Ernie Engineer has developed a new plug-in electric vehicle with a 24 kWh battery pack. Charging the pack to its full capacity requires a total of 30 kWh of electricity from the charging station.
Suggest an industrial symbiosis for establishing an eco-industrial park (EIP) based on the industrial processes and their inputs and outputs shown in Table 19.5. The current site only has the pulp
You plan to take a loan of $500,000 and wish to pay it off each month over a 30-year period. If the annual interest rate is 5 percent, what will your monthly payment be?
We learned in Chapter 2 about the islands of trash in global oceans (Figure 2.7). Figure 2.7:Will the concept of a circular economy be able to address this problem? Describe the changes that will be
What is the intervention matrix?
The life cycle network for manufacturing widgets is shown in Figure 10.12. Figure 10.12:1. Write down the technology and intervention matrices for this network. 2. Calculate the life cycle flows
Explain allocation by displacement with an example.

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