Hydrogen Fuel Cells

• A fuel is a substance which releases energy when burned
• Hydrogen is used as a fuel in rocket engines and in fuel cells to power some cars
• A fuel cell is an electrochemical cell in which a fuel donates electrons at one electrode and oxygen gains electrons at the other electrode

  • H2 → 2H+ + 2e-
  • O2 + 4e- → 2O2-
• The hydrogen-oxygen fuel cell produces electricity by combining both elements, releasing energy and water

  • The overall equation for the reaction within a hydrogen fuel cell is: hydrogen   +   oxygen   →   water
• The diagram below shows the setup of a hydrogen fuel cell

  A) current

  B) air

  C) unused gases

  D) cathode

  E) electrolyte

  F) anode

  G) excess fuel and water

  H) fuel

  
• The diagram below shows the setup of a hydrogen fuel cell

  • The air entering provides the oxygen
  • The fuel entering is hydrogen
  • The only chemical product made is water
• Hydrogen-oxygen fuel cells are becoming more common in the automotive industry to replace petrol or diesel engines
• Advantages of hydrogen and oxygen fuel cells

  • They do not produce any pollution: the only product is water whereas petrol engines produce carbon dioxide, and oxides of nitrogen
  • They release more energy per kilogram than either petrol or diesel
  • No power is lost in transmission as there are no moving parts, unlike an internal combustion engine
  • Quieter so less noise pollution compared to a petrol engine
• Disadvantages of hydrogen and oxuygen fuel cells

  • Materials used in producing fuel cells are expensive
  • Hydrogen is more difficult and expensive to store compared to petrol as it is very flammable and easily explodes when under pressure
  • Fuel cells are affected by low temperatures, becoming less efficient
  • There are only a small number of hydrogen filling stations across the country
  • Hydrogen is often obtained by methods that involve the combustion of fossil fuels, therefore releasing carbon dioxide and other pollutants into the atmosphere
• You should be able to state advantages and disadvantages of the hydrogen-oxygen fuel cells in comparison to a petrol engine.
• An input of energy is needed to drive electrolysis reactions whereas in fuel cells, electrical energy is produced from spontaneous chemical reactions
• NASA has used hydrogen and oxygen to fuel space missions for decades
• • Hydrogen oxygen fuel cells

  A) LEOA

  B) Anode

  C) electrolyte

  D) cathode

  E) negative

  F) positive

  G) GERC

  H) oxygen

  I) water

  J) electrons

  K) electrodes

  L) electrodes

  M) electrolyte

  N) hydrogen

  
• What is the differences between electrolysis and chemical cells?

  Electrolysis requires electricity for chemical reactions to take place while chemical cells uses the chemical reactions to produce electricity