A PEM (Proton Exchange Membrane) fuel cell generates electricity by separating hydrogen into protons and electrons. The membrane allows protons to pass through, while electrons travel through an external circuit—producing usable electrical power. At the cathode, oxygen from air combines with the protons and electrons to form water.
The basic reactions
* Anode: Hydrogen is split into protons (H⁺) and electrons (e⁻).
* Cathode: Oxygen reacts with H⁺ and e⁻ to produce water (H₂O).
* External circuit: electrons flowing through a load produce DC electricity.
What makes PEM fuel cells appealing
* Fast start and response compared with some other fuel cell types
* Low operating temperature relative to high-temp fuel cells
* High power density and compact stack designs
* Scalable: stacks can be sized or combined for different power levels
What a PEM fuel cell needs to run well
* Clean hydrogen supply (purity and pressure/flow within spec)
* Adequate air supply and oxygen access
* Thermal management (removing heat)
* Water management (keeping the membrane properly hydrated without flooding)