Biobattery

1. Ecowatt Biobattery Calvin College Engineering Senior Design Team 10 March 28, 2008

2. Outline • Introduction • Design • MFC • Power Regulation • System Monitoring • Feed/Waste System • Budget • Moving Forward

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

4. Project Division Four Main Parts of Our Biobattery Project • Microbial Fuel Cell • Electrical Monitoring • Electrical Regulation • Feeding and Case Design Introduction Design Budget Moving Forward

5. 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 Design Budget Moving Forward

6. Microbial Fuel Cell Design • Species: Geobacter Metallireducens • Most Efficient Colonization and Power Density • Widely tested • Membrane: Cellophane vs Nafion • Balance Cost and Permeability • Electrode: Carbon Cloth vs Carbon Porous Block Introduction Design Budget Moving Forward

7. 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 Design Budget Moving Forward

8. Anode Cube Waste Output Food Input Electrode Location (Each Face) MFC Design Regulation Monitoring Food/Waste Budget

9. Design • Fuel cell arrangement and composition • Will use a combination of serial and parallel circuit design • Lower chance of battery and circuit failure Introduction Design Budget Moving Forward

10. Design • Regulation • Must output 4.75V-5.25V and 100mA-500mA for USB compatibility • Must overcome low current problem • Must step up voltage from about 3.3V to 5V • Will use the Maxim MAX1524 Boost Controller Introduction Design Budget Moving Forward

11. Regulator Circuit Fig. Regulator circuit Introduction Design Budget Moving Forward

12. Parallel vs. Series Configuration Regulator Regulator M F C M F C Fault signal Fault signal Monitor Monitor Fig. Parallel configuration Fig. Series configuration Introduction Design Budget Moving Forward

13. Parallel configuration • Parallel configuration of regulator and monitor circuits • Preserve system integrity Introduction Design Budget Moving Forward

14. MFC Monitor Design • 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 Design Budget Moving Forward

15. MFC Monitor Design Voltage output from MFC Feed/waste removal signal ADC micro-controller Fault signal LCD Fig. Block diagram Introduction Design Budget Moving Forward

16. Monitor Design Initial State Vin MFC Waste Interrupt Output interrupt alert warning good bad Fig. State Machine Introduction Design Budget Moving Forward

17. MFC Monitor Design • AVR butterfly kit • Atmega169 micro-controller • 10 bit ADC & LCD • Low power consumption: < 500µA • RoHS compliant • No speciality hardware/software need for programming Fig. Block diagram Introduction Design Budget Moving Forward

18. Feeding and Waste System • Food Solution Bladder • Tubes and Valves • Thumbscrew Valves to Control Rate • One Way Valves to Prevent Backflow • Cubes Fed in Sets of 2, Bottom to Top • Waste Tank Introduction Design Budget Moving Forward

19. Feeding and Waste System Food Solution Bladder Filled by User Periodically Cathode Tank Anode Cube Anode Cube Anode Cube Anode Cube Waste Tank Emptied by User Periodically Introduction Design Budget Moving Forward

20. 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 Design Budget Moving Forward

21. Budget • Preliminary Budget estimation = $750 • Spent • Geobacter & media • Testing components such as tubes, • AVR butterfly kit • $350 Introduction Design Budget Moving Forward

22. Budget • Planned • Electrodes and membrane • Feeding and waste system • Electrical components • $400 Introduction Design Budget Moving Forward

23. Budget • Donation • Test equipments from chemistry and biology departments • Plexiglas, carbon cloth and membrane Introduction Design Budget Moving Forward

24. Obstacles and Plans • Case design • Need to find a tank for the cathode • Need to select and acquire a feed bladder • Must find a waste tank • Must select an appropriate feed rate Introduction Design Budget Moving Forward

25. Obstacles and Plans • Bacteria testing • Must have a bio-film formation on the electrode • Need to select a secondary, non-competitive aerobic bacteria • Plan to allow Geobacter to colonize electrodes before applying secondary bacteria • Plan to create a large supply of media Introduction Design Budget Moving Forward

26. Obstacles and Plans • Electrical regulation • Need to order parts • Need SchmartBoard to solder surface mount parts • Need to test circuit in lab • Electrical monitoring • Need to interface the different components with the monitoring system • Complete system test Introduction Design Budget Moving Forward

27. Questions?