Diesel and Gasoline: Energy Heavyweights

Transcription

1 AK Target grades: 9-12 AK GLEs: Science [9/10/11] SA1.1 [9] SA2.1 [10] SB2.1 Reading Math [9/10] [9] N-3 [9] E&C-3, 4 [9/10] S&P-1 [9/10] PS-3 [9] PS-4 [9/10] PS-5 Set up time: 20 minutes Class time: Two to three class periods Overview: Students will investigate how much energy is contained in a gallon of diesel and in a gallon of gasoline. Then they will compare the energy density of various fuel types. Using conversion factors and estimations, they will rank fuel types on a spectrum. Objectives: Students will learn the units of energy and power, approximate how much energy is in a gallon of diesel and the amount of work that it can do, and how this energy compares to other sources of energy. Materials: How Do Diesel and Gasoline Compare to Other Sources of Energy? student worksheet calculator 5-gallon buckets with lids filled with water, buckets if available, though the activity can be done with fewer (for optional Gear Up activity) stopwatch (for optional Gear Up activity) set of stairs-- either between floors in a building or bleachers in a gym (for optional Gear Up activity) Background: Fossil fuels are an important part of everyday life for many Alaskans, and the amount of concentrated energy that fossil fuels contain is often underappreciated. Many Alaskan communities depend on diesel to fuel generators that produce all of their electricity. Gasoline is important for powering vehicles such as cars, 4-wheelers, and snowmachines. Other important Alaskan energy sources include coal and wood energy. How do these different energy sources compare in terms of how much energy they provide? Vocabulary List: British Thermal Unit (BTU) - a unit used to measure energy. It is the quantity of heat required to raise the temperature of one pound of water one degree Fahrenheit and it is equivalent to 1055 joules. A BTU is approximately the amount of energy that one match stick gives off.

2 2 coal - a fossil fuel formed from dead organisms (mainly ancient plants) that were buried underground under heat and pressure for millions of years. Coal is classified depending on its properties, including how much energy it contains. anthracite - oldest type of coal (over 300 million years) that is hard and shiny with a high heat content and low moisture content; it is primarily mined in Pennsylvania. bituminous - an old coal (50 million to 300 million years) with a high heat content and low moisture content. In Alaska, it is mined at Wishbone Hill Mine in Sutton. It is also mined in Appalachia, the Midwest, and the West. sub-bituminous - a young coal (10 million to 50 million years old) with a medium to low energy content and a medium to high moisture content. In Alaska, it is mined at Usibelli Coal Mine in Healy. It is also mined in Wyoming and Montana. lignite - a very young coal (less than 20 million years old) with a low energy content and a high moisture content. It is mined in Texas, North Dakota, Montana, and the Gulf States. cord - a unit used to measure firewood; one cord is 128 ft 3 of wood and measures 8 feet long x 4 feet wide x 4 feet tall. crude oil - a liquid fossil fuel formed from dead organisms (usually zooplankton and algae) that were buried underground under heat and pressure for millions of years. Crude oil is a mixture of different lengths of hydrocarbons (long molecular chains of carbon and hydrogen atoms) that can be separated out depending on the length of the hydrocarbons to produce fuels, including diesel and gasoline. energy - the ability of a system to do work; this might refer to either potential or kinetic energy. Potential energy (stored energy) includes chemical, mechanical, nuclear, and gravitational energy. Kinetic energy (motion energy) includes radiant, thermal, motion, sound, and electrical energy. joule (j) - a unit used to measure energy. It is equal to the force of one newton on an object acting through a distance of one meter. kilowatt (kw) - a unit used to measure power. One kilowatt equals 1,000 watts (W). kilowatt-hour (kwh) - a unit used to measure energy. A kilowatt-hour is the amount of energy used if you use 1000 watts for one hour and is equivalent to 3,412 BTUs. power - the rate at which work is performed or energy is converted; units of power include both an amount of energy and a length of time. therm - a unit used to measure energy. A therm equals 100,000 BTUs. The term therm is usually used when referring to quantities of natural gas a therm of natural gas is 100 ft 3 of natural gas. watt (W) - a unit used to measure power. One watt equals one joule per second

3 3 (j/s). A typical incandescent light bulb uses 60 W to keep the light bulb lit for one hour. wood energy - energy stored in wood. Wood energy can refer to firewood, wood chips, or wood pellets. Gear Up: Have students brainstorm the sources of energy that they depend on daily. What uses diesel? What uses gasoline? How would their lives be different if they no longer had access to diesel or gasoline? Discuss the different definitions of energy and power with the students; while energy and power are often used interchangably in layman s terms, they are two different (though related) concepts when applied to physical science. Optional Gear Up extension activity Students can experience the physics of energy by doing physical work. Students can convert kinetic energy into potential energy by overcoming gravitation forces and carrying 5-gallon buckets of water up stairs (if 5-gallon buckets are not available, other heavy objects can be substituted, such as bag of kitty litter). Divide the class into small groups and conduct a contest to see how much power each group can produce by having groups race against each other to move the 5-gallon buckets of water up the stairs. 1. Fill as many 5-gallon buckets of water as available (ideally around buckets) and cover with lids to cut down on the amount of spilled water. Take turns timing each team as they carry the buckets up the staircase. If there isn t an available staircase, they can repeatedly lift the buckets onto tables and then place them back on the ground to simulate the height of a staircase. Record each team s length of time to complete the task. 2. Use the following equation to calculate how much work was done (this calculation should be the same for all the groups): work = mgh whereas: work = potential energy of the water (in joules, j) m = mass (in kilograms, kg; 1 gallon of water = 3.8 kg) g = gravity (9.8 m/s 2 ) h = height (in meters, m; this will need to be measured)

4 4 3. Use the following equation to calculate each group s power: power = work / time whereas: power = watts (j/s) work = joules (j) time = total number of seconds (s) the team took to complete the task 4. If one gallon of gasoline contains 125,000 BTUs and one BTU is equivalent to 1055 joules, calculate how much gasoline would be needed to do the equivalent amount of work. gasoline equivalent (gallons) = work (j) x (1 gallon of gas / 125,000 BTUs) x (1 BTU / 1055 j) 5. If 1 joule = 2.8 x 10-7 kwh, calculate how many kwh of work the teams did. Using the local price for a kwh of electricity, how much money did each team earn for their work? earnings = (joules X 2.8 x 10-7 kwh) x (cost / kwh) City Cost/kWh 1 Utility Name Anchorage $0.12 Anchorage ML&P - Residential Barrow $0.11 Barrow Utilities & Electric Co. - Residential Bethel $0.52 Bethel Utilities Corporation - Residential Dillingham $0.39 Nushagak Electric Cooperative - Residential Fairbanks $0.20 Golden Valley Electric Association - Residential Juneau $0.11 AEL&P - Residential Kotzebue $0.58 Kotzebue Electric Association - Residential Tanana $0.69 Tanana Power Company, Inc. - Residential 1 Values courtesy of Cold Climate Housing Research Center Show what a generous teacher you are by paying your students for the work they performed (this shoud be a fraction of a penny!)

5 5 Activity: Students will work through the problems in the How Does Diesel and Gasoline Compare to Other Sources of Energy? student worksheet. This worksheet includes mathemathical equations and conversions, comparisons, and explanatory questions. Extension: 1. Depending on the source, the number of BTUs in a gallon of diesel varies slightly. Why is there not one given standard? Is diesel a pure substance or a mixture? How does this affect the amount of energy in a gallon of diesel? 2. Students can investigate energy prices in their community. Standardizing their costs by price per BTU, what is the most affordable energy and what is the most costly? Why is electricity often one of the more expensive types of energy available? Where does electricity come from? Additional Resources: U.S. Energy Information Administration Energy Units and Calculators Explained Fairbanks Natural Gas, LLC This website includes cost comparisons of locally available fuels. Usibelli Coal Mine Usibelli is a coal mine located in Healy, Alaska; thier website is rich with information about coal and mining. Cooperative Extension Service Rural Development Wood Energy The Cooperative Extension Service provides information regarding harvesting and utilizing wood energy in Alaska.

6 6 Alaska Grade Level Expectations addressed: Science Performance Standards [9] SA1.1 asking questions, predicting, observing, describing, measuring, classifying, making generalizations, inferring, and communicating. [9] SA2.1 formulating conclusions that are logical and supported by evidence. [10] SA1.1 asking questions, predicting, observing, describing, measuring, classifying, making generalizations, analyzing data, developing models, inferring, and communicating. [10] SB2.1 examining energy (i.e., nuclear, electromagnetic, chemical, mechanical, thermal) transfers, transformations, and efficiencies by comparing useful energy to total energy. [11] SA1.1 asking questions, predicting, observing, describing, measuring, classifying, making generalizations, analyzing data, developing models, inferring, and communicating. Reading Performance Standards [9] Explaining connections among main ideas/concepts (text to self, text to text, text to world). [10] Explaining connections among main ideas/concepts (text to self, text to text, text to world). Math Performance Standards [9] N-3 [using models, explanations, number lines, real-life situations L] describing or illustrating the effects of arithmetic operations on real numbers (M1.4.3). [9] E&C-3 multiplying or dividing rational numbers including integers with whole number exponents (M3.4.3). [9] E&C-4 determining rate by using ratio and proportion (M3.4.5). [9] S&P-1 [designing, collecting L], organizing, displaying, or explaining the classification of data in real-world problems (e.g., science or humanities, peers, community, or careers) using information from tables or graphs that display two sets of data [or with technology L] (M6.4.1). [9] PS-3 representing mathematical problems numerically, graphically, and/ or symbolically, translating among these alternative representations; or using appropriate vocabulary, symbols, or technology to explain, justify, and defend strategies and solutions (M8.4.1, M8.4.2, & M8.4.3). [9] PS-4 following and evaluating an argument, judging its validity using inductive or deductive reasoning and logic; or making and testing conjectures (M9.4.1 & M9.4.2). [9] PS-5 using real-world contexts such as science, humanities, peers, community, careers, and national issues (M & M10.4.2). [10] S&P-1 [designing, collecting L], organizing, displaying, or explaining the classification of data in real-world problems (e.g., science or humanities,

7 7 [10] PS-5 using real-world contexts such as global issues and careers (M & M10.4.2). Alaska General Content Standard addressed Cultural Standards CS B 2-4 3) make appropriate choices regarding the long-term consequences of their actions; and 4) identify appropriate forms of technology and anticipate the consequences of their use for improving the quality of life in the community. Acknowledgment: This material is based upon work supported by the Department of Energy under Award Number DE-EE Disclaimer: This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.