
An electrochemical cell that converts the chemical energy of a fuel, like hydrogen, into electricity.A fuel cell is an electrochemical device that directly converts the chemical energy of a fuel, typically hydrogen, and an oxidant, usually oxygen from air, into electricity, with water and heat as byproducts. Unlike a battery, which stores energy internally, a fuel cell requires a continuous supply of fuel and oxidant to produce electricity. Fuel cells are highly efficient compared to combustion engines because they bypass the intermediate steps of heat and mechanical work, converting chemical energy directly to electrical energy. They are a key technology for clean energy, as they produce no harmful emissions when run on pure hydrogen.
The principle of the fuel cell was discovered by William Grove in 1839, who demonstrated that combining hydrogen and oxygen in an electrochemical cell could produce electricity. The first practical fuel cell was developed by Francis Thomas Bacon in the 1950s, leading to their use in NASA's Gemini and Apollo space missions.
A fuel cell consists of an anode, a cathode, and an electrolyte membrane between them. At the anode, hydrogen gas is split into protons and electrons. The protons pass through the electrolyte, while the electrons travel through an external circuit, creating an electric current. At the cathode, oxygen molecules combine with the protons and electrons to form water. The overall reaction is 2H₂ + O₂ → 2H₂O, with electricity and heat released. The efficiency is limited by factors like internal resistance and activation overpotentials, but modern fuel cells can achieve over 60% electrical efficiency.
Fuel cells are used in transportation (electric vehicles, buses, forklifts), stationary power generation for buildings and backup systems, and portable power for electronics and military applications.
The Apollo space missions used fuel cells to provide both electricity and drinking water for the astronauts, as the reaction produces pure water as a byproduct.













