A fuel cell is an electrochemical device that produces electricity from a reaction between a fuel and an oxidant. The fuel is usually a hydrogen-rich gas, and the oxidant is usually oxygen from the air. Fuel cells are similar to batteries, but they can operate indefinitely as long as they have a supply of fuel and oxidant.
Some of the emerging trends in fuel cell technology include the use of solid oxide fuel cells (SOFCs), the use of proton exchange membrane fuel cells (PEMFCs), and the use of direct methanol fuel cells (DMFCs).