A fuel cell is an electricity generation device that utilizes the reverse principle of water electrolysis to produce electricity.

Fuel cells, despite being commonly mistaken as a type of battery due to their name, are, in fact, electricity generation devices that use the reverse principle of water electrolysis to produce electricity by reacting hydrogen with oxygen, resulting in the generation of electricity and water. Unlike battery-based power generation, which requires charging, fuel cells will continue to generate electricity as long as fuel (hydrogen and oxygen) is supplied. They have even been used successfully in spacecraft. One of the significant advantages of fuel cells is that they can continuously generate power as long as you provide them with hydrogen and oxygen, and they produce water as a byproduct, which can be used as drinking water. In other words, as long as you can ensure a supply of hydrogen, you can generate power, especially on Earth, where you can utilize the oxygen in the air.