Chapter 5 - Hydrogen Fuel Cell Opportunites Flashcards
Give 3 reasons why hydrogen is used in fuel cells
Hydrogen has a high energy density
The only by product of hydrogen is water
Hydrogen fuel cells are more energy efficient than internal combustion engines
Describe 2 properties of hydrogen gas that make it suitable for use as a fuel
It’s has a high energy density compared with other fuels
It is readily available as it can use water as a raw material
List two methods of bulk hydrogen production currently used
Steam reforming of fossil fuels
Electrolysis of water using high pressure and temperature
Outline the bulk production of hydrogen by electrolysis of water
The electrodes are placed in water, after this an electric current is passed through the electrodes, the water is then split into hydrogen and oxygen
What is the equation for production of hydrogen by electrolysis of water
2H2O - 2H2 + O2
How’s does the process of steam reforming of fossil gases work for the production of hydrogen
Natural gas in the form of methane will release hydrogen when exposed to a superheated system
How does the process of photocatalytic water splitting to produce hydrogen work
Water is passed over a semi conductor material with light shining directly on it. The semiconductor material will the catalyse the water which splits it
What are the two equation for photocatalytic water splitting and where do they occur
First reaction is at the semiconductor electrode
H2O > 0.5 O2 + 2H
Second reaction is at the counter electrode
2H + 2e > H2
What is the most sustainable form of hydrogen production and why
Photocatalytic water splitting because the it uses light which is abundant and does contribute to greenhouse gas emissions and water there is plenty of
Name 4 of the most common forms of hydrogen fuel cell
Polymer electrolyte membrane (PEM)
Alkaline
Phosphoric acid
Solid oxide
Describe how a PEM fuel cell works
The fuel cell converts chemical energy into electrical energy
The hydrogen and oxygen react together to produce an electric current, heat and water
Hydrogen releases electrons at the anode
The electrons flow through the circuit to the cathode
Water is formed at the cathode
What happens at the anode of a typical hydrogen fuel cell
Hydrogen atoms are split into protons and electrons at the anode. The protons pass through the electrolyte layer and the electrons leave the cell and follow a circuit.
What happens at the cathode of a typical hydrogen fuel cell
The protons and electrons recombine at the cathode. These combine with the introduced oxygen to form water and heat.
State three possible applications of hydrogen fuel cells
Stationary generation as backup or in remote locations
Stand alone power supplies for telecommunications
Transport
What are the challenges of using hydrogen as an energy source for transport
The production may involve the use of fossil fuels which produce harmful gases
It’s very expensive
It must be stored at cool temperatures which requires special containers which cost more
The cost of installing the infrastructure is a challenge
A large amount of hydrogen is required to produce the same amount of energy as petrol and diesel
