Objectives By the end of the subtopic learners should be able to:
Define energy conversion.
Identify energy conversions.
Construct energy chains and describe how solar energy is changed to other forms of energy.
Identify energy converters and describe how energy is changed in an energy converter.
Energy conversion
It is the process of changing one form of energy to another. Chemical potential energy can be converted to different forms of energy.
Solar energy can also be changed into electrical energy by the use of a solar cell or photovoltaic cell.
A motor vehicle engine converts chemical potential energy in petrol and diesel into heat energy which is transformed into the kinetic energy that moves the vehicle.
Energy chains
Energy chains refer to a series of how energy conversions occur in sequence.
Below are some examples of how energy can change from one form to another. These are called energy chains.When an electrical jug is switched on , the following change that takes place:
When a rock drops from a high place, gravitational potential energy is converted to kinetic energy as the rock falls and then to sound and heat as it hits the ground and causes a sound as in the diagram below.
When coal is burnt, the energy changes in the following way:
Energy Converters
An energy converter is any device that converts energy from one form to another. The following are examples:
Solar panels
The solar panel converts solar energy to electrical light energy, heat energy, sound energy etc.
Inverters
A solar inverter converts the electricity from solar panels' direct current (DC) into alternating current (AC) that can be used by the plugs in houses for TVs, computers, and other wired products.
Solar panels cannot create AC power by themselves; they need the helping of a solar inverter.
Hydro- electric generators
Hydroelectric power is power derived from the energy of falling water and running water.
Other examples of energy converters are
Light bulb which converts electrical energy to light energy.
Generator converts mechanical energy to electrical energy.
Steam engine works as follows, potential chemical energy stored in the coal is converted into heat by burning.
The heat is converted to mechanical energy by: 1. Heating water into steam, 2. Steam expands to force a piston to move, 3. Pistons drive a shaft that eventually makes the wheels of the train turn. Mechanical energy becomes kinetic energy as the train moves.
Electrical motor converts electrical energy into mechanical energy.
The battery contains stored chemical energy which is converted to electrical energy which is converted into mechanical energy.
Green Plants convert light energy, normally from the sun, into chemical energy that can be later released to fuel the organisms' activities.
Hwange and Kariba power stations
Hwange Thermal Power Station is located in Matabeleland North, Zimbabwe.
Coal is delivered to the station by an overland conveyor belt.
Water which is piped from the Zambezi River is pumped into reservoirs next to the station and conveyed by gravity to its point of use.
Hot coal boils water to produce steam which powers the turbine to turn on the generator which then produces electricity that will be transferred to the different parts of the country.
Thermal power stations use steam to drive generators.
Coal is used as fuel to heat the water and produce steam.
The energy converters at Hwange power station are generators which are driven to produce electricity.
Kariba hydro- electric power station
Hydroelectric power is power derived from the energy of falling water and running water which is trapped and put to good use.
The water stores gravitational potential energy which is released when the water falls on the turbines kinetic energy is produced and the turbines start to move thereby creating electrical energy.
Solar Energy
Solar power is the conversion of sunlight into electricity, either directly, or indirectly.
They are an important and relatively inexpensive source of electrical energy.
When producing solar power, the solar panels collect energy from the sun and convert it to electrical energy which is stored in the batteries as chemical energy.
Solar panels are solar energy converters.
Green plants.
They are solar energy converters.
The process by which green plants convert solar energy to chemical energy is called photosynthesis.
The part of the leaves that enables this process is the leaves because of the green colour called chlorophyll which traps sunlight.
SUMMARY
Energy can neither be created nor destroyed but can be changed from one form to another.
Energy converters are devices which cause energy changes.
Energy changes can be written as energy chains.
Fuels have stored chemical energy that can be used to produce heat or generate electricity.
