S

Microbial Fuel Cell

(MFC)

Using Bacteria to Generate Electricity

This project is funded by

NSF-1004083

What are MFCs & How Do

They Work?

S MFCs are bio-electrical devices that harness the natural metabolism of microbes to produce electrical power

S Within MFC, microbes consume the sugars and other nutrients, and release a portion of the energy contained within the food in the form of electricity

S By linking bacterial metabolism directly with electricity production, the MFC eliminates the extra steps necessary in other fuel cell technologies

S Bacteria provides a cheap source of electricity

This project is funded by

NSF-1004083

Dirt = Power

S Microbes thrive throughout all

soils, sediments, and streams

S Microbes have the unique ability

that enable them to release

electrons onto metal compounds

such as rust

S “electrogenic” microbes are able

to “breathe” metal compounds

Mr. Clean

(aka Shewanella)

The Iron-Breather

(aka Geobacter)

2 Key Players

This project is funded by

NSF-1004083

Electron Transfer

S One electrode, called the anode is placed in a nutrient rich/oxygen poor environment

S Microbial community forms on the anode, and its metabolic pathways begin to breakdown the nutrients

S Highly reduced biomolecules with extra electrons attached to them donate their spare electrons to the anode one of three ways direct transfer, electron shuttling, or through nanowires

This project is funded by

NSF-1004083

The MudWatt

S Once the electron has been transferred to the anode, it then travels to the cathode reacting with the oxygen molecule and a proton to form H2O and generating an electrical current

S Power generation is continuous as long as there are nutrients available within the anodic media

S In an open-system soil-based MFC, nutrients are replenished by the decay of fresh plant and animal material giving it an indefinite lifespan

oxygen rich zone

oxygen poor zone

This project is funded by

NSF-1004083

MudWatt Steps

S Put ~3 cups of soil in bowl

S (Optional) Add mystery ingredient

Hint: if your mystery ingredient is liquid, add just enough to make the soil “cookie

dough” consistency

S Add water until “cookie dough” consistency

S Record your ingredients (and volume fraction of secret ingredient if

one was used)

Make Fuel

This project is funded by

NSF-1004083

MudWatt Steps

S Attach electrodes to dome lid (through donut disk)

S Attach ruler sticker to the side of vessel

S Put mud in vessel up to 1cm. Pat smooth

S Place in Anode (make sure there are no air bubbles)

S Put in more soil up to 4 cm

S Place in Cathode

S Let rest for 2min

S Decant liquid if needed (Cathode cannot be submerged)

Construct MudWatt

This project is funded by

NSF-1004083

S

MudWatt Tutorial Video http://news.keegotech.com/2012/04/26/new-tutorial-video/

This project is funded by

NSF-1004083