Biobattery

1. Ecowatt Biobattery Calvin College Engineering Senior Design Team 10 April 24, 2008

2. Outline • Introduction • Microbial Fuel Cells • Regulation • Monitoring • Feeding / Case

3. Team 10: Members Jared Huffman Chris Michaels Achyut Schrestha Brianna Bultema

4. Why Biobattery? • Problems of Conventional Batteries • “Hard to Do” • Interdisciplinary Talents Introduction Microbial Fuel Cells Regulation Monitoring Feeding/Case

5. Design Goals • USB Power output • 5V, 5% tolerance • 0.1-0.5A • Refillable Food Supply with Alert • Semi-Continuous • System Monitoring • User friendly • Indicates Failure Mode • Improved Power/Volume Ratio • Anode Cube Introduction Microbial Fuel Cells Regulation Monitoring Feeding/Case

6. Decision-Making Process • Brainstorm (Group and Individual) • Discuss Design Requirements • Research • Design • Present Design to Team • Refine Design • Present Refined Design to Team • Order Parts • Assembly • Testing Introduction Microbial Fuel Cells Regulation Monitoring Feeding/Case

7. Project Division Four Main Parts of Our Biobattery Project • Microbial Fuel Cells • Monitoring • Regulation • Feeding and Waste Introduction Microbial Fuel Cells Regulation Monitoring Feeding/Case

8. How Microbial Fuel Cells (MFC) Work • Story of Electrons: • Anode • Electrons from Acetate to Geobacter • Geobacter sends electrons outside itself to electrode • Cathode • Electrons combine with Oxygen and Protons to form water Schematic courtesy of Derek R. Lovely (Microbial Energizers: Fuel Cells the Keep Going?) Introduction Microbial Fuel Cells Regulation Monitoring Feeding/Case

9. Microbial Fuel Cells • Bacteria: Geobacter Metallireducens • Electrode Material: Carbon Cloth • Membrane Material: Nafion vs Cellophane • Membrane Electrode Assembly: Sandwich • Facultative Aerobic Bacteria Introduction Microbial Fuel Cells Regulation Monitoring Feeding/Case

10. Regulation • Output: 4.75V-5.25V, 100mA-500mA for USB Compatibility • Must step up voltage from 3.0V to 5.0V • Will use the Maxim MAX1524 Boost Controller Introduction Microbial Fuel Cells Regulation Monitoring Feeding/Case

11. Regulation Introduction Microbial Fuel Cells Regulation Monitoring Feeding/Case

12. Parallel vs. Series Configuration Regulator Regulator M F C M F C Fault signal Fault signal Monitor Monitor Parallel Configuration Series Configuration Introduction Microbial Fuel Cells Regulation Monitoring Feeding/Case

13. Monitoring System • Goal • Monitor the status of the system and communicate relevant status to user • Requirements • Update user the system status • feed and waste removal • voltage produced by MFC • circuit integrity, for e.g. over-current, short circuit • Use minimum power to monitor the system • User friendly • Components RoHS compliant and lead free Introduction Microbial Fuel Cells Regulation Monitoring Feeding/Case

14. Monitoring System Initial State Vin MFC Waste Interrupt Output interrupt alert warning good bad State Machine Introduction Microbial Fuel Cells Regulation Monitoring Feeding/Case

15. Monitoring System • AVR butterfly kit • Atmega169 micro-controller • 10 bit ADC & LCD • Low power consumption: < 500µA • RoHS compliant • No speciality hardware/software need for programming Block diagram Introduction Microbial Fuel Cells Regulation Monitoring Feeding/Case

16. Anode Cube Waste Output Food Input Electrode Location (Each Face) Introduction Microbial Fuel Cells Regulation Monitoring Feeding/Case

17. Feeding and Waste System • Food Solution Bladder • Tubes and Valves • Thumbscrew Valves to Control Rate • Check Valves to Prevent Backflow • Cubes Fed in Sets of 2, Bottom to Top • Waste Tank Introduction Microbial Fuel Cells Regulation Monitoring Feeding/Case

18. Feeding and Waste System Food Solution Bladder Replaced by User Periodically Cathode Tank Anode Cube Anode Cube Anode Cube Anode Cube Waste Tank Emptied by User Periodically Introduction Microbial Fuel Cells Regulation Monitoring Feeding/Case

19. Conclusion • Achieved Goal of Advancing Existing Designs Toward Feasible Product • Future Projects • Full Testing of Cellophane Membrane • Produce Smaller Cube: Fabrication Methods • Platonized Electrodes to Allow Air Cathode

20. Acknowledgements • Professor Ray Hozalski, Civil Engineering, University of Minnesota – Twin Cities, for samples/supplies of electrodes, membranes, and information on MEAs. • Chris Harrington, Graduate Student Researcher, University of Minnesota – Twin Cities, for help with implementation procedures. • Professor Randall Brouwer, Engineering Department, for supplying VHDL code for ADC interface. • Sam Brower, Media Productions Calvin Alum, for various visual design and photographic assistance. • Bob DeKraker, Engineering Department, for logistical support with procurement of circuit components. • Rich Huisman, Chemistry Department, for assistance with salt bridge supplies. • Lori Keen, Biology Department, for assistance in biological procurement and lab support. • Professor Walter Rawle, Engineering Department and Senior Design Team Mentor, for meeting with our team and assisting us with the in progress reviews. • Professor Gemma Reguera, Michigan State University, for providing technical information and expertise. • Professor J. Aubrey Sykes, Engineering Department, for his ongoing role as the senior design advisor and for all of this feedback about our project. • Professor John Wertz, Biology Department, for assistance in Microbiology growth and experimentation.

21. Questions?