Fuel cell technology, despite its recent popularity as a possible solution for a fossil-fuel free future, is actually quite old – the principle was discovered in 1838 and the first fuel cell was developed in 1843. The operating principle of a fuel cell is fairly straightforward: it is an electrochemical energy conversion device that converts the chemical energy from fuel (on the anode side) and oxidant (on the cathode side) directly into electricity. Today, there are many competing types of fuel cells, depending on what kind of fuel and oxidant they use. For instance, a hydrogen fuel cell uses hydrogen as fuel and oxygen as oxidant. In microbial fuel cells (MFCs), the naturally occurring decomposing pathways of electrogenic bacteria are used to both clean water and produce electricity by oxidizing biological compounds from wastewater and other liquid wastes, even urine.