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International Student Science Conference. 2-8 July 2012 Hong Kong. Optimizing the Microbial Fuel Cell as an Alternative Fossil Fuel Source Philip Ong, Alex Cheah, Daniel Chew Anglo-Chinese School (Independent), Singapore. Introduction – The Microbial Fuel Cell.
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International Student ScienceConference 2-8 July 2012 Hong Kong Optimizing the Microbial Fuel Cell as an Alternative Fossil Fuel Source Philip Ong, Alex Cheah, Daniel Chew Anglo-Chinese School (Independent), Singapore
Introduction – The Microbial Fuel Cell • A bio-electrochemical system that uses bacteria to produce electricity • Converts chemical energy to electrical energy by catalytic reaction of microorganisms • Used to generate electricity for storage
Our Aims • Curbing carbon emissions by offering a cheap, efficient method of obtaining energy • To conserve fossil fuels and oil • To reduce the emissions of environmentally-unfriendly substances into the earth
Our Set-Up • Our experiment involved the use of a soil-based Microbial Fuel Cell (MFC) through the construction of a Winogradsky Column. • Variables: • [Independent]: Salinity as controlled by the amount of NaCl per set-up • [Dependent]: Current (in miliamperes) • [Controlled]: Temperature, Location, Container Size & Shape, Type of electrode, Amount of soil.
Materials and Apparatus • Materials: • 1. Clay soil used: 50% clay [Al2Si2O5(OH)4]50% soil [SiO2] • (400g per set-up) • 2. Sulfur • (50g per set-up) • 3. Water • 4. Newspaper Shreds • (10g per set-up) • 5. NaCl • Apparatus: • 1. 2 Graphite Electrodes per set-up (as the anode and cathodes) • 2. 2 Crocodile Clips • 3. Multimeter • 4. Stopwatch • 5. Plastic containers
Analysis • Increase ionic strength Decrease resistance • I = 1.6 x 10-5 x Specific Conductance (in µmho/cm) • I = ½ Σ zi2 mi • Provide nutrients • Tonicity: Too much salt causes crenation • Lower oxygen levels
Limitations • Carbon surfaces not pure • Denitrification of nitrogen containing functionalities • Pt electrodes might oxidize separate substrates • Electroactive chemicals naturally present • Contaminants easily absorbed
Conclusion • Optimal range: 4000ppm-7000ppm • Good current output • Renewable energy source • Easily accessible
Further Research • Different genera involved • Optimal soil for involvement in MFC • Using other substitutes for soil eg. Wastewater • Research into MFCs as a method of reducing toxicity of soil • Use of Sulfate Reducing Bacteria • Polysulfides to sulfur • Electrochemically active bacteria
References • Newton. Oxygen Levels in Salt and Fresh Water. http://www.newton.dep.anl.gov/askasci/chem03/chem03339.htm • U.S. Geological Survey. Saline water. http://ga.water.usgs.gov/edu/saline.html • CaCt. Chemical Reactivity: A Study Guide. http://www.science.uwaterloo.ca/~cchieh/cact/applychem/reactivity.html • University of Massachusetts: College of Engineering. Chapter XVIII: Electrochemical methods. http://www.ecs.umass.edu/cee/reckhow/courses/572/572bk18/572BK18.html • Glass Properties. Definitions: Resistance, Specific resistance (resistivity), Conductance, Specific conductance (conductivity). http://glassproperties.com/resistivity/Conductivity_Resistivity.pdf • Xi Wang et al., Impact of salinity on cathode catalyst performance in microbial fuel cells (MFCs). International Journal of Hydrogen Energy [online] 2011, 36, 13900-13906 http://www.engr.psu.edu/ce/enve/logan/publications/2011-Wang-etal-IJHE.pdf • Korneel Rabaey et al., Microbial Fuel Cells for Sulfide Removal. Environ. Sci. Technol. [online] 2006, 40, 5218-5224 http://www.microbialfuelcell.org/Publications/LabMET/Rabaey%20Environ%20Sci%20Techn%2040%205218-5224%20Sulfide%20removal.pdf