5.4.6 Fuel Cells

Question 1

What are they?

Answer 1

• Electrochemical cell
• Fuel donates electrons at one electrode
• Gains electrons at the other
• Fuel becomes oxidised as it enters cell
• Creates potential difference within cell

Question 2

What is the hydrogen-oxygen fuel cell?

Answer 2

• Combines both elements to release energy and water

Question 3

Advantages of hydrogen-oxygen fuel cells?

Answer 3

• Water is only product, environmental benefits over other types of cell
• All bond energy converted to electrical energy (no heat or light, unlike combustion)
• No harmful oxides of nitrogen produced (happens in combustion at high temps in an engine)
• Can be used on space craft (water product can be drank by astronauts)

Question 4

Disadvantages with fuel cells?

Answer 4

• Hydrogen very flammable, storage causes safety hazards
• Thick cylinder walls storing hydrogen are expensive
• Non-renewable (due to hydrogen production from crude oil industry)
• Hydrogen high energy density, but because it is a gas density per unit of volume is low so large containers are needed to store it, which is expensive