1. ENERGY AND
CHANGE
RENEWABLE SOURCES OF ENERGY

2. ENERGY
• energy is a property of matter. It can be transferred between objects, and
converted in form. It cannot be created or destroyed. Energy exists in many
different forms. Examples of these are: light energy, heat energy,
mechanical energy, gravitational energy, electrical energy, sound energy,
chemical energy, nuclear or atomic energy and so on. These forms
of energy can be transferred and transformed between one another.

3. RENEWABLE SOURCE OF ENERGY
• A renewable source of energy is energy from a source that is not
depleted when used, such as wind or solar power.
• Examples of renewable sources of energy:
Sunlight
 Wind
 Hydropower

4. SUNLIGHT
Sunlight can be used to produce electricity and to heat up water:
PHOTOVOLTAIC (PV) ELECTRICITY
• Produces energy from the sun.
• PV panels only produce electricity during daylight hours.
• We therefore need a storage system to be able to use the energy at night or
when it is cloudy
• Lead/acid batteries are the most common storage devices used with PV systems
– VERY EXPENSIVE

5. SOLAR WATER HEATING (SWH)
• A functional Solar Water Heater (SWH) must collect the sun’s energy and
store enough hot water for desired use
• The SWH comprises a collector and a storage tank
• The SWH may be of direct design or indirect design

6. Some examples of SWH models

7. PV CELLS AND
MODULES

8. WIND
How do we Generate Electricity from Wind Energy?
• The movement of air is used to propel blades. These blades then turn in the wind
and along with it an axle that is attached at the centre of the blades. The axle
caries over the energy to a gearbox and finally to the generator where the
electricity is generated. (Eskom, 2016)

9. WIND TURBINES

10. HYDROPOWER
• Hydro-power is energy generated by water moving downward due to gravity.
• Electricity is generated in Hydro-power plants.
• There are two systems in operation in South Africa:
• conventional hydro, and
• pumped storage systems.
• Power generation from these plants is limited as they rely on the water level of
the dams or rivers which in turn is affected by the rainfall in its catchment area
(Eskom, 2016).

11. Pumped storage system