This website aims to help someone to build a
microbial fuel cell (MFC) using relatively inexpensive and readily
available materials. The method is based on the microbial fuel cells
built by Abbie Groff, a student at Conestoga Valley High School in
Lancaster, PA. The research she performed with her MFCs helped her
win the Grand Champion Award at the 2005 Lancaster County Science
Fair. More information about her research can be found on her
This website is intended to be a rough guide to
constructing a MFC, not an exact step-by-step procedure.
Two heavy duty plastic bottles with sealable
Short section of plastic pipe (polyethylene
or PVC) for salt bridge
Means to connect pipe to bottles (plastic
flanges, end caps with holes drilled)
Salt (NaCl, KCl, KNO3, etc)
Food for the bacteria4
Fish tank air pump with plastic tubing
Sealing materials (epoxy)
Copper wire (plastic coated)
Wires with alligator clips
Multimeter for electrical measurements
Connect end caps of flanges to bottles
* Epoxy end caps or flanges to sides of plastic bottles.
* After epoxy has hardened, drill or cut holes through plastic
bottles to allow for contact between liquid and the salt bridge.
Assemble Salt Bridge
* Dissolve agar into boiling water (at concentration of 100g/L).
* Add salt to the agar/water mixture while the mixture is still
* Seal one end of plastic pipe.
* Pour agar/salt mixture into plastic pipe while it is still
warm and before it begins to thicken.
* Allow the agar/salt mixture to cool and solidify.
* Connect copper wire to piece of carbon cloth.
* Use epoxy to fasten the wire to the carbon cloth and to help
protect from corrosion.
* Test electrodes with multimeter - there should be a small
amount of resistance between a point on the carbon cloth and the
end of the wire opposite the cloth.
* For anode, pass wire through a hole in the bottle lid and seal
with epoxy. Cathode chamber does not necessarily need a lid.
* Connect salt bridge between the two plastic bottles and use epoxy to seal.
Add inoculum (wastewater, anaerobic benthic sediments) to anode
Add conductive solution (saltwater) to cathode chamber
Insert anode (connected to lid) into anode bottle. Add cathode to
cathode bottle. Begin bubbling air in cathode bottle with fish pump.
Connect external circuit through a resistor, and start measuring
Oxygen must be kept out of the anode chamber
For long-term operation, electrodes should be constructed in a
way that limits corrosion of copper wire due to contact with liquids
Power can be significantly increased by using a catalyst
(typically platinum) on the cathode. Note: Platinum is expensive.
1Agar should be available in most high school science labs. If not,
it can be purchased from several sources online.
2Carbon Cloth can be purchased online from www.etek-inc.com. The
carbon cloth necessary for the electrodes is standard carbon cloth
without wet proofing.
3Bacteria for a MFC can be obtained from several sources. A sample
of wastewater from a local wastewater treatment plant would contain
the proper microorganisms. Some locations at the plant may be better
than others for obtaining the proper organisms. Animal wastewater
from a farm would also work. Anaerobic benthic sediments in a creek
or lake would also be likely to contain the proper organisms.
4Most likely, wastewater or anaerobic sediments will initially
contain enough organic matter to serve as food for the bacteria, but
this will eventually run out. A food source (substrate) such as
glucose or acetate (vinegar) can then be used to maintain the MFC.