Chapter 5 Hydrogen Fuel Cell Opportunities

Question 1

Give two reasons why hydrogen is used in fuel cells.

Answer 1

Hydrogen has a high energy density per unit mass. Hydrogen fuel cells are more energy efficient than internal combustion engines / electricity generators.

Question 2

List two methods of bulk Hydrogen production currently used.

Answer 2

Steam reforming of fossil fuels.
Electrolysis of water using high pressure and temperature.

Question 3

Outline the bulk production of hydrogen by electrolysis of water. Your answer must include a relevant equation

Answer 3

Electrodes are placed in water. An electric current is passed through the electrodes. The water is split into hydrogen and oxygen.

2H20 > 2H2 + O2

Question 4

State one other method used for the bulk production of hydrogen.

Answer 4

Photocatalytic water splitting or steam reforming of fossil fuel gases.

Question 5

Name two of the most common forms of Hydrogen fuel cell.

Answer 5

Alkaline
Phosphoric acid.

Question 6

explain the operating principles of a PEM (Polymer Electrolyte Membrane) Hydrogen Fuel Cell. Your answer should include equations for the reactions occurring at the anode and cathode.

Answer 6

Hydrogen is introduced which is then oxidised / chemically split into H+ ions and electrons (at the anode).
* Protons migrate through the PEM.
* Electrons follow a conductive path between electrodes / follow a circuit / between electrodes either side of the PEM.
* Protons and electrons then re-combine at the cathode to form water and heat.

H2 > 2H + 2e- at anode
4H + 4e- + O2 > 2H2O

Question 7

With reference to the Anode and Cathode, explain the operation of a typical hydrogen fuel cell.

Answer 7

Anode;
Hydrogen atoms (H2) are split into protons (H+) and electrons (e-) at the anode. The protons pass through the electrolyte layer and the electrons leave the cell and follow a circuit / conductive path on their way to the cathode.
Cathode:
The protons (H+) and electrons (e-) recombine at the cathode. These combine with the introduced oxygen (O2) to form water (2H2O) and heat.

Question 8

State two possible applications of hydrogen fuel cells.

Answer 8

Stationary generation as backup or in remote locations.
Stand-alone power supplies for telecommunications installations.

Question 9

Discuss two challenges of using Hydrogen as an energy source.

Answer 9

Production costs as expensive to produce.
Transport issues as lack of infrastructure