In the Classroom
Alternative Fuels and Hybrid Technology A Classroom Activity Designed To Evaluate a Contemporary Problem Amy H. Roy MacArthur and Christine L. Copper* United States Naval Academy, Department of Chemistry, Annapolis, MD 21402; *
[email protected] A recent editorial in this Journal addressed energy issues and the need for student exposure to them (1). The editorial centers around information offered by Nathan S. Lewis in a presentation entitled “Scientific Challenges in Sustainable Energy Technology” (2). Among other things, Lewis presents feasibility data about several types of renewable energy such as biomass, wind, solar, and nuclear. Moore, in his editorial, suggests various ways in which Lewis’s work could be incorporated into assignments for chemistry students. He also suggests that classroom discussions of energy issues could lead to a wider propagation of this information throughout society and would show students that chemistry is relevant to solving a current worldwide problem. The assignment we present in this article could be used to fulfill Moore’s suggestion of addressing energy issues in a general chemistry class. While we acknowledge that energy calculations similar to those in this activity are sometimes found in “call out” boxes in general chemistry textbooks, we feel that this exercise goes beyond what is typically presented and puts the topic in the context of a real-world problem to be solved through the use of an executive order. Description of the Activity The activity described herein is derived from Executive Order 13423 entitled “Strengthening Federal Environmental, Energy, and Transportation Management” that President Bush signed on 24 January 2007 (3). The overall policy set forth by this directive is as follows: It is the policy of the United States that Federal agencies conduct their environmental, transportation, and energyrelated activities under the law in support of their respective missions in an environmentally, economically and fiscally sound, integrated, continuously improving, efficient, and sustainable manner.
Since we teach at a federal institution, it seemed reasonable to build an activity based on the executive directive. We chose to focus on the transportation portion of the directive since our general chemistry curriculum already contains a unit on fuels and lubricants and a laboratory experiment that allows students to compare the fuel content of several fuels. With regard to transportation, Executive Order 13423 states that any federal agency that operates a fleet of at least 20 motor vehicles, not including military tactical vehicles, must …(i) reduce the fleet’s total consumption of petroleum products by 2 percent annually through the end of fiscal year 2015, (ii) increase the total fuel consumption that is non-petroleum-based by 10 percent annually, and (iii) use plug-in hybrid (PIH) vehicles when PIH vehicles are commercially available at a cost reasonably comparable, on the basis of life-cycle cost, to non-PIH vehicles…
Table 1. Representative Compounds Used in This Exercise Fuel
Formula
2,2,4-Trimethylpentane, “isooctane” (representative hydrocarbon in gasoline)
C8H18
Hydrogen
H2
Methane (main component in natural gas)
CH4
Propane C3H8 (main component in liquefied petroleum gas, LPG) Methanol
CH3OH
Ethanol
CH3CH2OH
Methyl Linoleate C19H34O2 (main component in biodiesel made from soybeans)
Accomplishing point (i) above could come in the form of addressing energy efficiency issues of automobiles (e.g., buying vehicles that have better mile-per-gallon ratings, more focus on maintenance of vehicles to ensure high engine efficiency, etc.). To address mandate (ii) above, there are several viable alternatives to gasoline for use in fueling automobiles and these will be the focus of the items presented in this exercise (4–6). Specifically, each student is assigned to calculate the fuel value and energy density of a particular alternative fuel and then compare his or her fuel to gasoline and to fuels studied by other students in the class. For simplification, specific chemical compounds have been chosen to represent gasoline and several of the alternative fuels (Table 1). Calculations of standard enthalpy, entropy, and Gibbs energy are included in this activity; therefore, it can be incorporated into the coverage of thermodynamics. In addition to asking students to choose the best fuel to fulfill the requirements of Executive Order 13423 based on the energy density and physical characteristics of the fuel, the activity also requires them to consider how alternative fuels are produced and what impact their use has on the environment. Furthermore, since the executive order specifically mentions the need to use PIH vehicles when feasible, students are asked to research PIH vehicles and to describe how these vehicles are different from conventional and other hybrid vehicles. Assumptions Used To Simplify the Activity As with many other exercises that incorporate applications of material presented in the general chemistry curriculum, the calculations in this exercise have been simplified through the use of a few assumptions. It is important to point out to the students the complexity of comparing alternative and conventional fuels. We have guided the students to consider some of the
© Division of Chemical Education • www.JCE.DivCHED.org • Vol. 86 No. 9 September 2009 • Journal of Chemical Education
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In the Classroom
assumptions used in the questions asked in the activity (see the online material). For example, one substantial issue that should be addressed when comparing fuels is the life-cycle energy and greenhouse gas emissions impacts of the production and use of a fuel. The questions we ask about the production of biodiesel or ethanol and the environmental effects of hydrogen, methane, and biodiesel are meant to cause students to think about these life-cycle issues. The instructor can further discuss these issues by using resources such as those found in references (7, 8). Implementing the Activity The initial calculations of the thermodynamic data associated with each fuel could be completed during one hour of class time with students reporting results for their fuel to the class for compilation. Each fuel would be assigned to more than one student, which allows for collaborative work if desired. Once the initial data are compiled, the students could complete the exercise outside of class or could spend an additional in-class hour working on the activity. It should be noted that the later sections of the activity require the use of the Internet to acquire information regarding fuel production, environmental impacts of fuels, and characteristics of PIH vehicles. Specific Internet sites are provided in these parts of the exercise to guide the students’ work. The assignment could be expanded to incorporate a written communication component by asking students to summarize the class data and their conclusions in a succinct memo that states how they plan to comply with the requirements of part (ii) of Executive Order 13423. Conclusion The exercise presented herein can be used in a general chemistry course to address the very timely topic of alternative fuels and hybrid vehicles. It not only presents topics such as combustion and thermodynamics in a practical context, but also gives students the opportunity to critically assess data as they evaluate available fuel choices. The fact that this activity is based on a recent presidential order should lend it credibility in
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the eyes of students; that is, it is based on a real-world issue that must be addressed. After learning about the chemistry and issues surrounding the use of alternative fuels and hybrid vehicles, students will have the ability to understand and to educate others about these emerging technologies. Acknowledgments The authors acknowledge funding for this work provided by the Naval Academy Research Council in the form of a curriculum development grant. They also sincerely thank Bob Ferrante and Deb Dillner for their valuable input during the construction of this activity. Literature Cited 1. Moore, J. W. J. Chem. Educ. 2008, 85, 891. 2. Lewis, N. S. http://nsl.caltech.edu/energy.html (accessed Jul 2009). 3. Bush, G. W. Strengthening Federal Environmental, Energy, and Transportation Management: Executive Order 13423; Federal Register 2007, 72 (17), 3919. 4. Kemsley, J. Chem. Eng. News 2007, 85 (49), 55–59. 5. Demirbaş, A. Energy Sources 2002, 24, 601–610. 6. Ritter, S. K. Chem. Eng. News 2004, 82 (22), 31–34. 7. Wang, M.; Wu, M.; Huo, H. Environ. Res. Lett. 2007, 024001, 1–13. 8. Argonne GREET Model. http://www.transportation.anl.gov/ modeling_simulation/GREET/index.html (accessed Jul 2009).
Supporting JCE Online Material
http://www.jce.divched.org/Journal/Issues/2009/Sep/abs1049.html Abstract and keywords Full text (PDF) with links to cited URLs and JCE article Supplement
Student handout
Instructor guide
Journal of Chemical Education • Vol. 86 No. 9 September 2009 • www.JCE.DivCHED.org • © Division of Chemical Education
