Fuel Cells and Hydrogen as a Fuel — AQA GCSE Chemistry (Separate)
Fuel cells produce electricity directly from a chemical reaction, and hydrogen is a promising clean fuel.
What is a fuel cell?
A fuel cell is supplied with a fuel and oxygen (or air) and uses the energy from their reaction to produce a voltage continuously, as long as the fuel is supplied. Unlike a battery, it does not run down or need recharging.
The hydrogen fuel cell
In a hydrogen fuel cell, hydrogen and oxygen react to form water:
- Overall: 2H₂ + O₂ → 2H₂O.
- At the negative electrode, hydrogen is oxidised.
- At the positive electrode, oxygen is reduced.
The only product is water, so there are no carbon-based pollutants.
Advantages over rechargeable batteries
- No need to recharge — works as long as fuel is supplied.
- No polluting waste products at the point of use (only water).
- Fewer pollutants than burning fossil fuels.
Disadvantages
- Hydrogen is a gas, so it is difficult to store and transport safely.
- Hydrogen is often made using energy from fossil fuels, which produces pollution elsewhere.
- Fuel cells and hydrogen production can be expensive.
Exam tips
- A fuel cell produces a voltage from a fuel + oxygen, continuously.
- Hydrogen fuel cell overall reaction: hydrogen + oxygen → water.
- Main advantage: the only product is water (clean at point of use).
- Main disadvantages: storing hydrogen and making it cleanly.