Microbial Fuel Cells And You!

What are MFCs? o MFCs are bioelectrical devices that harness the natural metabolisms of microbes to produce electrical power directly from organic material

MFC Basics Oxygen Poor Oxygen Rich

Key Players Mr. Clean (aka Shewanella) The Iron-Breather (aka Geobacter) 1um

Key Players o Direct Transfer o Electron Shuttling o Nanowires Electron Transfer Mechanisms: Mr. Clean (aka Shewanella) The Iron-Breather (aka Geobacter) 1um

Key Players o Direct Transfer o Electron Shuttling o Nanowires Electron Transfer Mechanisms: Mr. Clean (aka Shewanella) The Iron-Breather (aka Geobacter) 1um

Respiration cell OC CO 2 SO 4 -- H2SH2S

Redox Gradients  Max potential ~1.2 V (= potential difference between NADH and O 2 )  If terminal e- acceptor has lower potential than O2:  Bacteria gain less ATP per mole organic carbon oxidized  Remaining energy is available to be used in MFC

Anaerobic Microbial Food Chain

Applications

Soil-based MFCs

The MudWatt +Food

The MudWatt

MudWatt Steps 1) Make Fuel 2) MudWatt Construction 3) Monitor 4) Submit Data

MudWatt Steps  Put ~3 cups of soil in bowl  (Optional) Add mystery ingredient Hint: if your mystery ingredient is liquid, add just enough to make the soil “cookie dough” consistency  Add water until “cookie dough” consistency  Record your ingredients (and volume fraction of secret ingredient if one was used) 1) Make Fuel

MudWatt Steps  Attach electrodes to dome lid (through donut disk)  Attach ruler sticker to the side of vessel  Put mud in vessel up to 1cm. Pat smooth  Place in Anode (make sure there are no air bubbles)  Put in more soil up to 4 cm  Place in Cathode  Let rest for 2min  Decant liquid if needed (Cathode cannot be submerged) 2) Construct MudWatt

MudWatt Steps 3) Monitor (Perform this technique every week) Nob #1= Blinker Nob #2 = 100 Nob #3 = 500 Nob #4 = 1000 Nob #5 = 5000 Nob #6 = 10,000  S1) Switch the electronics panel to Open Circuit mode by turning all switches off.  S2) After 30 minutes, check the voltage across the two leads using any voltmeter (black to “-“, and red to “+”). Record the voltage and the resistance. (the resistance is infinite under “Open Circuit” mode)  S3) Repeat S2 for the 5 different resistances provided on the electronics panel. Turn only one Nob on at a time. The resistance for each Nob is outlined as follows (in Ohms):

MudWatt Steps  Enter the data you’ve collected at 4) Submit Data Thank You! With the data collected and submitted by you and your fellow Keegoites, we hope to uncover trends and peculiar behaviors of microbial fuel cell technology. In this way, we aim to catalyze the development of this technology in the hope that someday MFCs will be a viable option in providing affordable and reliable energy for those who would benefit greatly from it. Developed by the public, for the public. All hail the Keegoites!