Hydrogen Fuel Cell Simulator

Fuel Cell Stack

H2 feed rate 1.0x

Circuit load (resistance) 1.0x

Stack temperature 80°C

Current

–

Cell voltage

–

Efficiency

–

Water produced

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How it works

Hydrogen gas fed to the anode is split by a catalyst into protons and electrons. The proton-exchange membrane lets H⁺ ions through but blocks electrons, forcing them out through the external circuit as usable current — lighting the bulb you see. On the far side, the electrons rejoin the protons and combine with oxygen at the cathode to form water, which condenses and drips away.

Anode:    2H2 → 4H⁺ + 4e⁻
Cathode:  O2 + 4H⁺ + 4e⁻ → 2H2O
Overall:  2H2 + O2 → 2H2O

Nernst:  E = E° − (RT/nF)·ln(Q)

H2 feed rate — how fast hydrogen molecules arrive at the anode; more fuel supports more reactions per second, up to what the membrane can carry.
Circuit load — the external resistance the electrons must push through; a lighter load (lower resistance) lets more current flow but drags cell voltage down under the internal resistance.
Stack temperature — higher temperature speeds up the catalytic reaction and ion transport through the membrane, raising efficiency, per the Nernst equation's temperature term, until heat losses start to dominate.
Efficiency — the fraction of hydrogen's chemical energy converted to electrical work rather than lost as heat; real PEM stacks run roughly 40–60% efficient.

Real-world relevance: this exact reaction, scaled up across thousands of stacked cells, is what powers hydrogen fuel-cell vehicles, backup power systems and some grid-scale storage — its only tailpipe byproduct is water.

H₂ molecule Electron (circuit) Proton (membrane) H₂O droplet

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