A fuel cell “stack” is only part of a working system. Most real installations include additional components that keep the stack within safe and efficient operating limits. This is commonly called the balance-of-plant (BOP).
1) The fuel cell stack
- MEA layers (membrane + catalyst + diffusion layers)
- Bipolar plates / flow fields
- Gaskets, endplates, compression hardware
The stack is the electrochemical core that generates DC power.
2) Hydrogen supply train
- Pressure regulator (or rated supply)
- Valves and shutoff
- Flow control and purge management
- Filters or purification (where required)
Hydrogen delivery must be stable, dry enough (as required), and within safe pressure/flow limits.
3) Air supply and cathode management
- Blower/compressor (if active air supply is needed)
- Air filtration
- Exhaust/water handling
Air delivery affects performance strongly; starvation can damage the stack.
4) Cooling and water management
PEM fuel cells generate heat and water. Systems need:
- Cooling plate/loop (for higher power) or passive cooling (small systems)
- Condensate management
- Humidification or hydration management (depending on design)
5) Electrical power conditioning
Fuel cells output DC with a voltage that changes with load. Many systems include:
- DC/DC conversion
- Battery/supercap buffering
- Load control and protections
- Isolation monitoring and fault handling (application dependent)
Why BOP matters: Most field issues (instability, poor output, faults) are caused by airflow, water handling, thermal limits, or controls—not the MEA alone.