A fuel cell converts chemical energy directly into electrical energy through a continuous electrochemical reaction, without combustion.
How It Works
In a hydrogen–oxygen fuel cell (PEM type):
- Anode (−): H₂ → 2H⁺ + 2e⁻ (oxidation)
- Cathode (+): O₂ + 4H⁺ + 4e⁻ → 2H₂O (reduction)
- Overall: 2H₂ + O₂ → 2H₂O
PEM Hydrogen Fuel Cell
Advantages vs Disadvantages
Advantages
- Only product is water — zero emissions
- Higher efficiency than combustion engines (~60% vs ~25%)
- Quiet operation, no moving parts
- Hydrogen has the highest specific energy
Disadvantages
- H₂ storage is difficult (low energy density by volume)
- Most H₂ currently from steam reforming of natural gas (not green)
- Expensive platinum catalysts
- Lack of refuelling infrastructure
Think About It
If hydrogen is produced by electrolysis using solar energy, is the fuel cell truly "zero carbon"?
Yes — green hydrogen from renewable electrolysis creates no net CO₂. However, the production of the solar panels and fuel cell components still has an embedded carbon footprint (lifecycle analysis).