Microbial Fuel Cell
Recommended for High School and K-8.
A microbial fuel cell (MFC) is a bio-electrochemical system that converts chemical energy to electrical energy by the bacterial interaction of microorganisms. MFCs are a very clean and efficient method of energy production. Though a relatively new form of alternative energy, MFCs are being investigated as potential power sources for sewage treatment plants.
During metabolism, bacteria stick to the surface of an electrode forming a bacterial community called a biofilm. The sticky biofilm is made up of extracellular proteins, sugars, and bacterial cells that form an electrical potential gradient allowing the transport of electrons. As the electric potential increases, the rate of bacterial metabolism increases. Bacteria will continue to grow as long as there is an abundant supply of nutrients. Maximum power output is dependent upon the thickness of the biofilm. If it is too thick, the electrons must travel too far to get to the electrode; if it is too thin, there are not enough electrons produced.
Build a microbial fuel cell capable of illuminating an LED using pond sludge.