Heard of Beer batteries? They create energy from bacteria that feed on waste water. Its actually called “microbial fuel cells” (MFCs). The best part – you can make this at home too.
Materials Needed –
2 plastic bottles with sealable lids
Short section of pvc pipe
Plastic flanges, end caps with holes drilled
Agar
Salt (NaCl, KCl, KNO3, etc)
Carbon cloth
Bacteria
Food for the bacteria
Fish tank air pump
Sealing materials
Resistors
Copper wire with insulation
Wires with alligator clips
Multimeter for electrical measurements
How to make it –
1. Connect the end caps of flanges to bottles
Use Epoxy end caps or flanges to the sides of plastic bottles.After it has hardened, drill holes through plastic bottles to allow contact between liquid and the salt bridge.
2. Assemble Salt Bridge
Dissolve the agar into boiling water (100g/L) and add salt to the agar/water mixture while its still hot. Then seal one end of the plastic pipe.Pour the agar/salt mixture into the plastic pipe while its still warm and before it begins to thicken.Now, allow the agar/salt mixture to solidify.
3. Assemble electrodes
Connect the copper wire to the piece of carbon cloth. Then use epoxy to fasten the wire to the carbon cloth. Now, test the electrodes with multimeter.For the anode, pass the wire through a hole in the bottle lid and seal with epoxy. The cathode chamber does not need a lid.
4. Assemble MFC
Finally connect the salt bridge between the two plastic bottles and use epoxy to seal.
Running the Beer Battery –
First, add inoculum to the anode chamber and then conductive solution (saltwater) to cathode chamber. Now, insert the anode into the anode bottle and similarly for cathode. Then, begin bubbling air in cathode bottle with the fish pump. Finally, connect the external circuit through a resistor, and start measuring voltage.
Source – Lifehacker
