3. How do we generate electricity?
Cooking is just one activity that requires energy that usually comes from wood, charcoal or LPG. Many parts of Africa do not have a regular and reliable supply of electricity and this is a problem for industries and hospitals in particular. The most common way to make electricity is to burn coal, oil or gas to generate steam which is then used to drive a turbine. Coal, oil and gas are expensive and eventually they will run out. They also produce a great deal of pollution.
There are alternative ways to produce electricity, other than burning fuels, which your students should be aware of. (Resource 6 provides some background information on how electricity is produced). It is a good idea – especially with secondary school children – to make science relevant to everyday life by introducing them to some of the big issues that face society. The teacher in Case study 3 gets her students to consider the advantages and disadvantages of alternative sources of electricity. Activity 3 involves students working in groups to solve a problem.
Case study 3: Working in groups to make a decision
Mrs Asantesked her class if they knew some ways in which electricity could be generated. She collected their ideas on the board. She encouraged them to talk about the problems that often arise. Joseph told them how his father worked at a small hotel and was responsible for the small diesel generator. It keeps breaking down, and last week, the price of diesel was so expensive that the manager cut the number of hours the generator was used. A number of guests had complained!
Then Mrs. Asante gave them some information about the different ways of generating electricity. She had written the information on large pieces of paper before the lesson (see Resource 6) and she stuck them to the walls so they could all see them. She also borrowed some books from a nearby school that the students could refer to. The class had to work in groups and decide which method would be the best in their town or village. She asked them to consider the advantages and disadvantages of each method and to make a suggestion about the method that the government should develop in their region. Each group had to present their ideas to the rest of the class. They chose two people to present the information. They had to say what method they had chosen, why they had chosen it, and what the disadvantages might be.
Activity 3: Comparing diesel and solar power
In this activity students consider the advantages of solar panels over diesel generators. Start by gathering the class around the front and brainstorming the advantages and disadvantages of each method for generating electricity. The solar panels will probably seem much more attractive! However, the initial costs are very high. Resource 6 contains some background information on the approximate costs of each method of generating electricity. Ask the class to work in pairs to work out how long it would take for the solar panels to become cost effective. For older children, you could just write the table on the board and let them work out what to do. Alternatively, you could provide support by asking questions to guide them.
You will find that it takes over 10 years. However, there are other advantages of solar panels, such as electricity is available for more than four hours a day and no pollution is produced in the form of fumes or carbon dioxide. At the end of the lesson, ask each student to write a few sentences explaining what they have learnt from this exercise.