Kk5 - Fuel Cells

What are they?

Fuel cells are a specific type of galvanic cell that:

• produce electrical energy (and heat as a by-product) from a supplied fuel via a redox reaction

• require a continuous supply of reactants from an external source

• use porous electrodes to maximise efficiency of diffusion of gaseous reactants and to maximise the ability of catalysts

• are used to power small electronic devices, vehicles, and more.

Set up of a fuel cell (acidic)

• Hydrogen as an energy source and an acidic electrolyte

• Hydrogen gas is continuously pumped in as the fuel and oxidised at the anode

• Oxygen gas is continuously supplied as a reactant and reduced at the cathode

• Half reaction, overall reaction and theoretical cell voltage:

Set up of fuel cell (basic)

Advantages

• Lower emission of harmful sulfur and nitrogen-containing compounds ( compared with direct combustion of fuels)

• Low maintenance and running costs

• Quiet

• No direct CO2 emissions from hydrogen fuel cells

• Great efficient than direct combustion, partially if thermal energy produced is harnessed for car/home heating

Disadvantages

• Storage and safety issues associated with high explosive hydrogen fuel

• Expensive to manufacture (esp. porous electrodes)

• Required new infrastructure for hydrogen fuel e.g. Refill stations

• Hydrogen fuel generally produced via electrolysis of water

• Only as environmentally friendly as the electricity used in this process

• May not be as efficient or convenient as batteries