Mechanical Engineering 300 – Engineering Thermodynamics I

 

Sections 1 and 3                                               Spring Semester 2008

 

Homework 4a                                        Due Wednesday, March 19, 2008 

 

Imagine that you are an engineer.  The company for whom you are working is considering a billion-dollar investment in distilleries and related facilities to produce ethanol, which the company would market as a motor fuel.  Your task is to recommend to management either to pursue the investment in ethanol production or to terminate it.  You should base your recommendation on technical, economic, and ethical considerations. 

 

Read the following article from Chemical & Engineering News, Dec. 17, 2007, pp. 12-16.  This article provides two diametrically opposed opinions offered by two acknowledged experts, who, despite their expertise and professional stature, present very one-sided points of view and incomplete information. 

 

Reading this article will not prepare you to formulate a recommendation.  Instead the information in the article should suggest the questions that need to be answered.  The two, following chemical reactions may be useful.  (C8H18  represents octane, which you can consider as representative of “gasoline.”   C2H6O represents ethanol.)

 

C8H18 (l) + 12.5 O2 (g) ¾¾®  8 CO2 (g) + 9 H2O (g)       Dh = 44.43 MJ/kg C8H18

 

 

C2H6O (l) + 3 O2 (g) ¾¾®  2 CO2 (g) + 3 H2O (g)           Dh = 26.81 MJ/kg C2H6O

 

 

Based on your knowledge of thermodynamics and economics, answer the following questions.  Present your responses in the form of complete sentences.  (You may consult other sources of information, although it is not required.)

 

  1. Production of gasoline and ethanol are subject to a variety of governmental regulations.  Name two crucial economic factors, related to government policy as opposed to technical necessity, about which you will need complete, quantitative information, in order to execute your analysis.

 

 

 

 

 

  1. Suppose that ethanol were used as a primary fuel for spark-ignition, automobile engines, as opposed to an additive at concentrations < 10%, which is a current practice.  Name two technical considerations affecting automotive design, and speculate on their economic consequences. 

 

 

 

 

 

 

  1. To grow corn for producing ethanol, name two significant uses of petroleum. 

 

 

 

 

 

 

 

  1. To produce ethanol from corn, name two energy-intensive processes. 

 

 

 

 

 

 

 

 

  1. To recover oil from the earth, other than from existing oil reservoirs and wells, name two major costs. 

 

 

 

 

 

 

 

 

  1. To produce gasoline from crude oil, recovered from existing wells, name three processes requiring energy.  List them from the most energy-intensive to the least energy-intensive steps.

 

 

 

 

 

 

  1. In the context of growing food, does using corn to produce motor fuel give rise to an ethical dilemma?  Explain. 

 

 

 

 

 

 

 

 

 

  1. Some experts have proposed world-wide population control as a means to mitigate future energy and food shortages.  However, currently this proposal receives little publicity.  With a brief justification, state whether this proposal should be either promoted or discouraged. 

 

 

 

 

 

 

 

 

 

  1. Does burning ethanol in place of gasoline reduce the emissions of CO2?  Name several factors that you would need to know to answer this question. 

 

 

 

 

 

 

 

 

 

  1. Suppose that your company concludes that it can produce ethanol at approximately the same cost as gasoline per mile traveled.  What is the likely outcome, if this conclusion were erroneous?