STUDENT SPACE · TOPIC 3

Fuels and fuel cells

Compare energy sources and evaluate hydrogen–oxygen fuel cells.

The essentials

Combustion transfers chemical energy to the surroundings. Fuels differ in energy per unit mass and practical suitability.
Hydrogen and oxygen react to generate electricity, with water as the only chemical product.
At the point of use, a hydrogen fuel cell produces no CO₂, soot or carbon monoxide. It can convert fuel energy efficiently to electricity.

Try each question before opening its hint or answer. Use paper for calculations and diagrams.

Does a fuel cell make electricity by burning hydrogen in an engine?

Need a hint for Question 1?

Separate the vehicle reaction from the process used to make hydrogen.

Check Question 1

No. An electrochemical reaction generates an electric current.

Write the balanced overall equation for a hydrogen–oxygen fuel cell.

Need a hint for Question 2?

Balance hydrogen and oxygen atoms.

Check Question 2

2H₂ + O₂ → 2H₂O.

Give one advantage and one disadvantage of a hydrogen–oxygen fuel cell compared with a petrol engine.

Need a hint for Question 3?

Separate emissions at the point of use from storage and production issues.

Check Question 3

For example: no CO₂ at point of use; hydrogen is difficult to store and infrastructure is costly.

Use Lesson 3 in your worksheet for written practice. Your teacher will discuss those answers in class.