Section III: Applying Knowledge Pyrolysis Lab Summary In this lab activity, students learn about converting biomass into energy through the activity 12 process of pyrolysis. The experiment demonstrates pyrolysis through the heating of biomass material in the absence of oxygen to produce gas, liquid oil, and char. Students conduct the experiment in groups and complete a lab journal. n Subjects Mathematics, Science n Key Questions Background 1. What is pyrolysis? There are a variety of systems that can 2. What forms of energy are transform wood into energy for residential, generated through the process commercial, and industrial uses. Energy of pyrolysis? from wood can be used to generate n Objectives electricity, heat buildings, and produce steam for industrial purposes. In addition, By the end of the activity, combustible gas and liquid oil can be students will be able to do the following: extracted from wood through the process 1. Explain the process of pyrolysis of heating wood at a high temperature and the resulting energy forms in the absence of oxygen. This process, (SC.912.P.10.1; SC.912.P.10.4; called pyrolysis (pyro means fire and lysis SC.912.P.10.5). means decomposition), distills the wood 2. Explain the potential advantages into three main products: combustible gas, and disadvantages of creating liquid oil, and char. Pyrolysis is one of the energy through the process of first chemical reactions that occur when pyrolysis (SC.912.L.17.11). a biomass material is burned. The flames 3. Calculate and compare masses of biomass materials before and that are visible when the material is burning after the process of pyrolysis are not a result of the combustion of the (MA.912.A.2.7). material itself, but instead flames occur because of gases released through the process n Materials of pyrolysis. For example, when you build Bunsen burner and test tube should be assembled For each lab station: with care. a campfire, it slowly lights because it takes • Two samples of biomass materials time for the wood to be heated to the point Caution: The gas produced in this experi- (small wood splints, chips, pellets, of releasing gas. When the wood becomes ment can be explosive under pressure. In addi- shavings, mulch, or other readily hot, pyrolysis gas is released, and the fire tion, the oil produced is hot and can spew from available biomass materials) • Large test tube begins to burn. As more and more gas is the end of the glass tubing. Close supervision of • Rubber stopper with small hole released, the fire grows larger and larger. students is needed to prevent injury. Students that fits snuggly in test tube top Eventually, only ash is left. The fire goes out should wear safety goggles and should not • Glass tube that fits snuggly in because the ash does not release any gas. stand in front of the end of the test tube. The rubber stopper hole This lab activity demonstrates the test tube will be hot at the end of the experi- • Ring clamp stand process of pyrolysis through the heating ment—make sure students wait an adequate • Triple beam balance of wood chips and wood pellets (or other amount of time for the test tube to cool down • Bunsen burner or portable biomass materials) over a Bunsen burner or before disassembling the experiment. butane burner portable butane burner in a test tube sealed • Wood splint or matches Check each group’s setup before they light with a rubber stopper. Heating biomass • Stop watch the burner and begin the experiment. Also, • Safety goggles material will create a combustible gas that smoke will be released, so be sure to provide • Copies of Instructions and burns as it escapes through the glass tube in adequate ventilation. Student Lab Journal (one copy the rubber stopper. As the gas continues to per student) burn, you will see liquid oil begin to form in This activity was adapted from Renewables are Ready, the test tube. In addition, the biomass in the Creating Fuel from Biomass, Union of Concerned n Time Estimate Scientists, 2003 (http://www.ucsusa.org/assets/ test tube will be converted into char. documents/clean_energy/renewablesready_TOC.pdf). 50 minutes to 1 hour
Should We Use Wood for Energy? • Section III – Activity 12: Pyrolysis Lab 129 teacher Teacher Instructions
Assessment Preparation 1. It is highly recommended that students complete Activity 3: Biomass Basics Web- Suggestions quest prior to doing this activity. Activity 3 provides students with important knowledge and information about biomass and bioenergy that better enable them Objective 1: to understand this activity. Review answers to 2. Read the Background Information provided at the beginning of this activity Student Lab Journal and make copies if you plan to assign student reading before this activity. More summary questions 1 background information on woody biomass and conversion technologies is through 4. Answers to available in Activity 5: Case Study Jigsaw. Additional information on wood to questions 2 and 4 can be checked by reviewing energy conversion processes is available in the Resources section of this activity and student data tables, in fact sheets in the Supplemental Reading section of the curriculum: Systems That and sample answers to Convert Wood into Energy; Technological Processes: Bio-chemical; and Technological questions 1 and 3 are Processes: Thermochemical. provided in the Teacher 3. Review the complete lab setup and procedure instructions found in the Key. Instructions. Pay particular attention to the safety precautions noted. 4. Gather the required lab materials and supplies listed at the beginning of the Objective 2: activity. Biomass materials may be available from local lumber operations or Review answers to gardening centers. If time permits, it is helpful to try out the experiment on your Student Lab Journal own before doing it with your class. summary questions 5 and 6. Sample 5. Make copies of the Instructions and Student Lab Journal (one copy of each per answers are provided student). in the Teacher Key. Review calculations Procedure and measurements in 1. Divide your class into groups (four or five students per group is optimal) and Student Lab Journal distribute the Instructions and Student Lab Journal. data tables. 2. Introduce students to the process of pyrolysis. Ask students to give some examples of biomass and explain ways in which energy can be extracted from biomass. 3. Give instructions for or demonstrate set up of lab experiment, go over the lab procedure instructions, and answer questions students may have about the Extensions experiment. 4. Check each group’s setup before beginning the experiment. If time permits, try the 5. Instruct groups to begin the experiment. Walk around the classroom to ensure experiment with differ- students are wearing safety goggles at all times and provide assistance as needed. ent types of biomass. 6. Have students complete all portions of his or her Student Lab Journal. Each student Discuss the differences in should turn in his or her own Student Lab Journal, with completed data tables, the amount of time gas is diagrams, observations, and conclusion questions. released and burned when using different biomass types; compare before and after masses of the different biomass materials; discuss Resources • National Renewable Energy Laboratory: Biofuels: http://www.nrel.gov/learning/ the varying amounts of oil re_biofuels.html U.S. Department of Energy-Energy Efficiency and Renewable Energy-Biomass and char produced and • Program: Pyrolysis and Other Thermal Processing: http://www1.eere.energy.gov/ also how this relates to the biomass/printable_versions/pyrolysis.html concepts of efficiency and sustainability of various bio- mass sources.
130 Should We Use Wood for Energy? • Section III – Activity 12: Pyrolysis Lab Pyrolysis lab
Instructions LAB
After your teacher has demonstrated the setup and discussed safety procedures, follow the instructions below to conduct the pyrolysis lab experiment. All measurements, calculations, and diagrams should be recorded in the data tables in your Student Lab Journal.
1. Using a triple beam balance, determine the mass of the empty test tube (including the rubber stopper and glass tubing). 2. Fill the test tube half full with wood chips/wood splint pieces. 3. Determine the mass of the test tube half-filled with wood (including the rubber stopper and glass tubing) and record this figure in the data table. 4. Calculate the mass of the wood and record this figure in the data table. (Hint: Mass of wood = mass of test tube half-filled with wood – mass of empty test tube.) 5. Position test tube approximately 8 to10 cm from the top of the heat source. 6. Draw a diagram of your experiment setup thus far. 7. Make sure your teacher checks your setup before you light the burner. Put on your safety goggles and light your burner. 8. Carefully record your own observations throughout the experiment. 9. Start the stop watch and record the amount of time it takes for the gas to be released from the end of the glass tubing. You will see the gas begin to form in the test tube and eventually escape through the glass tubing. Record this time in the data table. 10. Light a splint or match and hold it approximately 2 centimeters from the end of the glass tubing. The gas will begin to burn. CAUTION: Hot gases and oil will be released from glass tubing—DO NOT stand in front of glass tubing and keep hands, arms, and face away from this area. 11. Start the stop watch and keep the burner lit for 2 minutes. Draw a diagram of what you see as the gas burns. 12. Turn the burner OFF after 2 minutes. 13. Restart the stop watch and time how long gas continues to be released from the glass tubing (the gas appears as smoke coming out of the glass tubing). Record this time in the data table. 14. Draw a diagram of what you see after you have completed the experiment. 15. Once the test tube is completely cooled, remove it from the ring clamp stand and determine the mass of the test tube (including the rubber stopper and glass tubing) and the mass of the remaining wood. Record these figures in the data table. (Hint: Mass of remaining wood = mass of test tube half-filled with wood – mass of empty test tube.) 16. Repeat the previous steps using the second type of biomass material provided by your teacher. 17. Answer the Summary Questions at the end of the Student Lab Journal. 18. Clean up your station and put away lab supplies as instructed by your teacher.
Should We Use Wood for Energy? • Section III – Activity 12: Pyrolysis Lab 131 Pyrolysis lab
LAB Student Lab Journal (1 of 4) LAB
______NAME date period
n Data Table 1 Biomass material: ______
Mass of Mass of test Mass of Time: Gas Time: Gas Mass of test Mass of empty test tube, rubber biomass released after released after tube, rubber remaining tube, rubber stopper, glass material (g) burner is lit burner is stopper, and biomass stopper, and tube, and extinguished glass tube material (g) glass tube (g) biomass post-experi- material (g) ment (g)
n Data Table 2 Biomass material: ______
Mass of Mass of test Mass of bio- Time: Gas Time: Gas Mass of test Mass of empty test tube, rubber mass material released after released after tube, rubber remaining tube, rubber stopper, (g) burner is lit burner is stopper, and biomass stopper, and glass tube, extinguished glass tube material (g) glass tube (g) and biomass post-experi- material (g) ment (g)
132 Should We Use Wood for Energy? • Section III – Activity 12: Pyrolysis Lab Pyrolysis lab
LAB Student Lab Journal (2 of 4) LAB
n Diagram 1: Experiment Setup Biomass Material I Biomass Material II
n Diagram 2: Conducting the Experiment Biomass Material I Biomass Material II
n Diagram 3: After Experiment Biomass Material I Biomass Material II
Should We Use Wood for Energy? • Section III – Activity 12: Pyrolysis Lab 133 Pyrolysis lab
LAB Student Lab Journal (3 of 4)
n Observations
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134 Should We Use Wood for Energy? • Section III – Activity 12: Pyrolysis Lab Pyrolysis lab
Student Lab Journal (4 of 4) LAB
Summary Questions
1 Describe the process of pyrolysis that you observed during this experiment.
2 How much mass was lost from each material?
3 Where did this mass go?
4 How did the two biomass materials compare in terms of mass remaining and time gas was released and burned?
5 What are the potential advantages and disadvantages of creating energy from wood and other biomass materials?
6 Brainstorm: what types of industries could use this process to extract energy and fuels from wood?
Should We Use Wood for Energy? • Section III – Activity 12: Pyrolysis Lab 135 136