Hydrogen-Oxygen Fuel Cells

• A hydrogen-oxygen fuel cell uses hydrogen and oxygen to produce electricity with water as the only chemical product.

Advantages & disadvantages of using hydrogen-oxygen fuel cells in comparison with gasoline engines in vehicles

The hydrogen-oxygen fuel cell

• Advantages:
  • Only chemical produced is water, which is harmless
  • Hydrogen can be made by the electrolysis of water, which is plentiful, on adding a little acid.
• Disadvantages:
  • Hydrogen is a gas. To reduce its volume and make it practical to use, it must be stored as a liquid under high pressure. This can be expensive or hard to maintain.
  • Hydrogen filling stations are not yet widely available.
  • Most hydrogen is obtained by fossil fuels, and where it is obtained by electrolysis, the electricity is mostly from power stations that burn fossil fuels. These are linked to pollution and climate change.

The gasoline engine

• Advantages:
  • Gas stations are widely available for drivers.
  • Gas is relatively cheap (varies depending on world supply)
• Disadvantages:
  • The burning of gas in engines produce harmful substances:
    • $CO_{2}$, linked to climate change
    • Oxides of nitrogen
    • $CO$ if gas burns in limited oxygen
    • Unburnt volatile gases from the gas
  • Petrol is obtained from oil, a limited and non-renewable resource.