main module mudWatt NGSS teacher’s guide © Keego Technologies LLC. All rights reserved.
Table of Contents Table of Contents 1 Introduction 2 Teaching Rationale Learning Objectives Essential Questions By The End of This Lesson...
Introduction Teaching Rationale Microbial fuel cells (MFCs) represent an exciting, emerging technology for generating electricity that is clean and reliable. In this module students will learn how electricity is produced by certain bacteria during their natural metabolic process and how a microbial fuel cell works. The progression of lessons provided in this module has been designed to give students the background and instruction necessary to engage in their own exploration of microbial fuel cells.
Introduction Learning Objectives 1. Microbial fuel cells (MFCs) are a clean energy source that can be used to generate electricity. 2. Natural metabolic processes of certain “electrogenic” bacteria can be used to generate electricity. 3. Nearly all soils, sediment and water contain electrogenic bacteria. 4. Energy can be transformed from one form to another: chemical energy (energy stored in the bonds of chemicals) into electrical energy (energy of moving electrons). 5.
Introduction Students will be able to: • • • • • Assemble a functional Microbial Fuel Cell Explain how a microbial fuel cell works Plan and conduct a scientific experiment using a MudWatt™ Microbial Fuel Cell Kit Measure the amount of power generated in a microbial fuel cell Explain how Microbial Fuel Cells are a clean, renewable energy source NGSS Alignment core ideas Core Idea LS1: From Molecules to Organisms: Structures and Processes LS1.
Introduction practices 55 Asking questions (for science) and defining problems (for engineering) 55 Developing and using models 55 Planning and carrying out investigations 55 Analyzing and interpreting data 55 Using mathematics, information and computer technology, and computational thinking 55 Constructing explanations (for science) and designing solutions (for engineering) 55 Engaging in argument from evidence 55 Obtaining, evaluating, and communicating information Vocabulary Microbe Photosynthesis Ce
Introduction Cathode Cellular respiration Electricity The site at which electrons are released (+) The process in which nutrients and sugars (e.g. glucose) are broken down and turned into useful energy within a cell The movement of electrons Electrogenic bacteria Bacteria capable of donating electrons to external receptors outside their bodies (e.g.
Pre-Assessments Pre-Assessment: Free Response Ask students to write down their ideas on the following questions using only what they already know: 1. What does “metabolism” mean? 2. How do plants get their energy? 3. How do animals get their energy? 4. How do microbes get their energy? 5. Do all animals require oxygen to survive? 6. Do all microbes require oxygen to survive? 7. What are independent and dependent variables in a scientific investigation? 8.
Pre-Assessments Pre-Assessment: Multiple Choice Ask students to answer the following questions using only what they already know: 1. The process by which plants get their energy is called: a. respiration b. photosynthesis c. breathing d. fermentation 2. The process by which food is burned to release energy in organisms is called: a. respiration b. photosynthesis c. breathing d. fermentation 3.
Pre-Assessments 7. In a scientific investigation, the “independent variable” is: a. what is changed in the set up b. what is kept the same in all the set ups c. the set up that has not been changed and is used for comparison d. what is measured 8. In a scientific investigation, the “dependent variable” is: a. what is changed in the set up b. what is kept the same in all the set ups c. the set up that has not been changed and is used for comparison d. what is measured 9.
Background Teacher Background Microbial fuel cells, also referred to as biological fuel cells, have been of interest to scientists as a source of electricity since the early 1900s. As our demand for energy continues to increase and our supply of energy resources continues to be stressed, we are constantly looking for alternative energy sources.
Background What are Microbial Fuel Cells? What are microbes? The term microbe, short for microorganism, is used to describe any tiny organism that is too small individually to be seen with the naked eye. To see a microbe you need to use a powerful microscope. Microbes are often associated with disease or illness, but microbes are also essential players in the recycling of nutrients on earth and in providing key ingredients necessary to support life.
Background Some bacteria are also autotrophs but use a process called chemosynthesis. In chemosynthesis bacteria take in materials such as carbon dioxide and hydrogen sulfide, or iron or ammonia and process them to make organic material. Finally, many other bacteria and organisms (like us) are heterotrophs, meaning they rely on external sources of organic matter from which they can get their energy. The bacteria that make the MudWatt work are heterotrophs.
Background sediment and surface water environment where oxygen is limited. Two common types of electrogenic bacteria, Shewanella (a.k.a “Mr. Clean”), and Geobacter (a.k.a. “The Iron-Breather”). How microbial fuel cells harness energy from microbial metabolism (Please refer to the MudWatt diagram on page 16.) Microbial fuel cells work because anaerobic bacteria create a thin film on an electrode buried in soils or sediment.
Background STUDENT HANDOUT What are Microbial Fuel Cells? Microbial fuel cells (MFCs) generate electricity using the natural ability of microbes to produce electrical power when they process food. To understand this process we need to understand how microbes get their energy. All living organisms need energy to live but where does that energy come from? You need microbes to make a microbial fuel cell work! The energy organisms need to live comes from the energy stored in the “foods” they eat.
Background Other organisms, particularly certain types of bacteria, are able to respire without oxygen being present. This is called anaerobic (without oxygen) respiration. Organisms that metabolize when oxygen is not present are called anaerobes. When oxygen is not present the electrons are taken up by elements other than oxygen, particularly metals like iron and sulfur. Chemistry Connection! Metals and other materials change their chemical form when used as electron acceptors, and become less toxic.
Background STUDENT HANDOUT How does a microbial fuel cell work? A microbial fuel cell takes advantage of electrogenic bacteria’s ability to give electrons to external materials. Physics Connection! For a fuel cell to function there must be two electrodes, an anode and a cathode, separated by a protonexchange membrane (PEM), which allows very small ions (such as protons) to move through it but will not allow larger ions, such as oxygen, to pass through.
Background Power generation from an MFC will continue as long as there are nutrients readily available. Since mud is full of complex sugars and other nutrients from decaying plant and animal matter that have accumulated over millions of years, there is plenty of food for the microbes and thus the MudWatt can continue to produce power for months to years! Quick Recap! MudWatt Microbial Fuel Cell Operation 1.
Scientific Investigations Activity 1: How does a microbial fuel cell work? Teachers: In this lesson students gain familiarity with the assembly and operation of the MudWatt™ Microbial Fuel Cell. Students make a prediction of the expected outcome and then measure, record, and graph the voltage produced over time to see how the power production changes with time. Students are evaluated using the experimental and group work rubrics provided at the end of these investigations.
Activity 1 Scientific Investigations Scientific Investigations STUDENT HANDOUT Activity 1: How does a microbial fuel cell work? How does a microbial fuel cell work? In this activity you and your partner will assemble a MudWatt™ Microbial Fuel Cell. You will be monitoring the MudWatt over 20 days to see how much power it generates over time. You will be evaluated using the experimental and group work rubrics provided. Procedure 1. Gather MudWatt™ kit and a few cups of dirt (1 kit per group). 2.
Activity 1 Scientific Investigations Predictions 1. When will the MudWatt LED begin blinking? 2. What will be the maximum amount of power (in μAmps) produced in 20 days? Data Collection 1. Check the MudWatt™ each day to see if the LED light is blinking. 2. Use the MudWatt Explorer app to measure and record the amount of current being produced (the app converts the number of blinks per minute the LED light produces into power in microWatts (μW)). 3.
Activity 1 Scientific Investigations Graphing Once all the data have been collected make a graph of the voltage (y axis) versus time (x axis). Be sure to include a title, axes labels, and units. Title: _________________________________________ 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Analysis 1. An independent variable is something that is changed on purpose during the experiment. What was the independent variable in this investigation? 2.
Activity 1 Scientific Investigations Analysis (cont.) 1. Describe the results. 2. Examine the graph and describe any trends, patterns, or interesting changes in the data over time. How (in what ways) did the amount of power change over time? Critical Thinking 1. What evidence did you have that electricity was being generated in the MudWatt™? 2.
Activity 1 Scientific Investigations Critical Thinking (cont.) 3. In a MFC what type of energy is being converted into electricity? 4. Write 4 questions that you still have after doing this investigation: 1. 2. 3. 4. 5. What changes could you make to the MudWatt™ to increase its power production? I could change: 1. 2. 3. 6. What else besides power output could you make on the MudWatt™? I could measure: 1. 2. 3. 7.
Activity 2 Scientific Investigations Activity 2: Maximizing Power Output in a MudWatt Teachers: In this investigation students manipulate variables to determine cause and effect between the variables with the goal of optimizing the amount of power output from the MudWatt™. Two MudWatts™ per group are used to conduct an experiment using a control. Students select one independent variable (of their own choosing) to change in one MudWatt™ while keeping the second MudWatt™ unchanged to serve as the control.
Activity 2 Scientific Investigations Scientific Investigations STUDENT HANDOUT Activity 2: Maximizing Power Output in a MudWatt In this investigation you are trying to find ways to modify the MudWatt so that it will produce the greatest amount of power. Your team will have two MudWatts. Both MudWatts should be identical except you will change one thing in one of the MudWatts. What can you think of to change? Use your imagination.
Activity 2 Scientific Investigations Selecting Variables (cont.
Activity 2 Scientific Investigations Activity 2: Maximizing Power Output in a MudWatt Time Procedure 1 class period for MudWatt assembly 1. Gather MudWatt™ kits (2 per group) and a 5-6 cups of dirt. Periodic monitoring over the course of 20 days 2. Acquire materials needed for manipulated variable. Materials 3.
Activity 2 Scientific Investigations Data Collection 1. Check the MudWatt™ each day to see if the LED light is blinking. 2. Use the MudWatt Explorer app to measure and record the amount of current being produced (the app converts the number of blinks per minute the LED light produces into power in microWatts (μW)). 3. Record the power output each day for 20 days in the data table. If the light is not blinking, record the value as 0.
Activity 2 Scientific Investigations Analysis 1. Describe the results. Examine the graph to see any trends, patterns, or interesting changes in the data and record those observations below. 2. What was similar about each of the Mudwatt™ set ups in this investigation? 3. What was different in each of the Mudwatt™ set ups in this investigation? 4.
Scientific Investigations Analysis (cont.) 5. Can you provide a scientific explanation for why the Mudwatts™ produced different amounts of power? What evidence can you provide to support your answer? (refer to your data) 6. Compare your results with those of another team. Which group’s MudWatt™ produced the most power? What was the highest and lowest amount of power, voltage and/or current recorded for each Mudwatt™? Team Highest power Recorded (uW) Lowest Power Recorded (μW) 7.
Scientific Investigations Analysis (cont.) 8. What would you change or do differently if you ran this experiment again? Explain why you would make that change. Critical Thinking 1.
Scientific Investigations Scientific Investigation Design Template What are you curious about? Design your own investigation using a MudWatt™ Microbial Fuel Cell! Develop a testable question and design and run your own investigation using a MudWatt™. Use the following template to help you through the steps involved in designing your own experiment.
Scientific Investigations Experiment Design Template Materials Procedure List all the materials and supplies you will need to conduct this investigation Write out each step in enough detail that someone else could do the same experiment from your directions.
Scientific Investigations Experiment Design Template Data Collection Record what happened. (Include units, times of measurements, sketches, etc.) Data Display Find the best way to display the data for ease of interpretation and viewing.
Scientific Investigations Experiment Design Template Analysis Examine the data and describe any patterns, trends, changes you can see. Conclusions Were you able to answer the investigation question from the results of this experiment? What did you find out? Did you get the results you expected? Why or why not? Did anything go wrong along the way? Identify anything that went wrong or that had to be changed during the experiment.
Scientific Investigations Experiment Evaluation Rubric Name: _______________________________ Section: ____ Date: _____________ 3 Problem Hypothesis Variables Observations Analysis/ Conclusion 1 0 Is clearly testable and is written in a clear and concise manner Is not clearly testable or not written in a clear manner Is not testable and is not written in a clear manner No problem given Relationship or trend predicted.
Scientific Investigations Group Experiment Evaluation Rubric Name: _______________________________ Section: _______ Date: ____________ Basic Skills 1 Working with others/ Cooperation Focus on task/ Commitment Team role fulfillment Communication/ Listening/ Information sharing Thorough Extensive 2 3 4 Sometimes cooperative, sometimes offered useful ideas. Rarely displays positive attitude. Cooperative, usually offered useful ideas.
Experiment Ideas Teacher’s Guide: MudWatt Experiment Ideas Note: For all of experiments mentioned below, you can use the “MudWatt Soil Standard” (aka the “MudWatt DirtBag”) to ensure you have a viable soil.
Experiment Ideas Independent Variable: Special ingredient from a the fridge Dependent Variable(s): Voltage, Current, and/or Power Experiment Notes: • With any special ingredient, you’ll want to add just a modest amount, and mix it well into the soil. We recommend using 1-part of special ingredient for every 5-parts (or more) of soil. • We recommend using liquid special ingredients. If you are using a solid special ingredient (e.g.
Experiment Ideas at very various time points until the temperature has stabilized (higher limit). Then place the MudWatt in an ice bath or refrigerator and do the same thing until the temperature has stabilized again (lower limit). • Be sure to compare your graphed results to known relationships of microbial growth vs temperature that can be found on the web (also copied below).
Experiment Ideas end of another), their voltages will be added, and the current will be averaged between them all. • When hooking up MudWatts in parallel (i.e. All the (+) ends together and all of the (-) ends together) their current will be added, and the voltage will be averaged between them all.
Experiment Ideas Experiment B B) Experimental Question: How can you find a MudWatt’s Maximum Power Point? (The art of Potentiometry) Independent Variable: The resistor value that is placed within the MudWatt’s Hacker Board Dependent Variable(s) / Measurables: Voltage, Current, Power Experiment Notes: • Microbial Fuel Cells behave much like solar panels do, in that they have a “Maximum Power Point” that is achieved when you apply an external resistance (i.e.
