An Introduction to Sediment Microbial Fuel Cells

1. An Introduction to Sediment Microbial Fuel Cells

2. What is a Fuel Cell? • A fuel cell is a device that generates electricity through a chemical reaction. • It is similar to a battery, but unlike a battery the chemicals can be continuously supplied

3. What is electricity? • Electricity is energy made available through the flow of electrons. Loses electrons Gains electrons

4. If both substances are in the same solution, then the electrons transfer directly and the energy is dispersed as heat.

5. How does it work? • If the two substances are separated, and the electrons are transferred through a wire then the energy is transformed into electricity. Tube filled with electrolyte solution e- Gains electrons Loses electrons Electrodes

6. Vocab Electrode: • The site at which electrons are either released or collected. • Two types of electrodes: • Anode (-): The site at which electrons are collected. • Cathode (+): The site at which electrons are released.

7. Vocab • Electrolyte solution: A solution that can carry ions between the anodic and cathodic chambers.

8. How do we apply this to a sediment microbial fuel cell? Cathode Water Anode Fish Tank

9. So, where are the chemicals?

10. What is the reaction? Two parts to the reaction: • Reaction in the anodic chamber + H2O  CO2 + H+ + electrons • Reaction in the cathodic chamber Oxygen + H+ + electrons  H2O Organic compound

11. For example: Anodic chamber C2H4O2 + 2H2O  2CO2 + 4H+ + 4e- OR C6H12O6 + 6H2O  6CO2 + 24H+ + 24e- Cathodic chamber 4O2 + 4H+ + 4e- 4H2O OR 6O2 + 24H+ + 24e-  12H2O

12. Why do we need the microbes? • The microbes are what make the reaction “go”. They are the catalyst. • A catalyst initiates or accelerates a chemical reaction but remains unchanged. • Example: enzymes

13. Kinda like this…