In the last section, you read about electrical energy.
What sources of electrical energy are used in Ontario?
There are three main sources of electrical energy:
• hydro-electric power plants
• nuclear power plants
• thermal-electric power plants
These sources are conventional energy sources. They have been used for a long time in many different
places. This section will discuss good and bad features of each energy source.
HYDRO-ELECTRIC ENERGY
Hydro-electric power plants use falling water to make electricity (Figure 1). The water starts at the top of a tall structure. The water falls down the structure.
Conventional Energy Sources
Key Question: What benefits and problems come with common sources of energy?
9.2
Hints
The word “plant”
here is not the kind that grows out of the ground. In this section, plants are buildings where energy is produced.
conventional energy source
a source of energy that has been widely used for many years
Figure 1 A hydro-electric power plant on the Niagara River
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The falling water hits structures called turbines. The turbines spin. The turbines change the mechanical energy into electrical energy in a machine called a generator. The electrical energy is delivered to homes through wires (Figure 2).
Hydro-electricity is a good energy source for two reasons:
• It does not cause much pollution.
• It uses water power, which is renewable.
Hydro-electric power is a renewable energy resource.
Hydro-electric power uses water. Water is replaced every time it rains. We can get energy from a hydro- electric power plant almost indefinitely.
However, hydro-electric power plants can cause some problems:
• They can flood large areas of land.
• They can block fish and animals from moving along a river.
• They can affect living things in and near the water.
• They can only be built in places near moving water.
renewable energy resource
a source of energy that can be used indefinitely, without running out
reservoir
turbine generator
long-distance power line
spillway dam
Figure 2 Moving water makes the turbine spin. The generator changes the water's mechanical energy into electrical energy.
NUCLEAR ENERGY
All matter is made up of tiny particles. These particles hold a lot of energy. We can use some of that energy by breaking apart those particles.
To get to the energy, we break apart the nucleus of the particles. The word “nuclear” comes from the word
“nucleus.” Breaking apart the nucleus releases a large amount of energy.
Nuclear power plants turn nuclear energy into thermal energy. The thermal energy heats water and turns it into very hot steam. The steam turns turbines to make electrical energy (Figure 3).
Figure 3 A nuclear reactor turns nuclear energy into electrical energy.
non-renewable energy resource a source of energy that could eventually be used up
Nuclear power plants often break up the particles in uranium. Uranium is very powerful. Even a small piece of uranium can create enough energy to power the turbine!
Nuclear energy is powerful, but it also has problems:
• Nuclear power plants are very expensive.
• Nuclear energy can be very dangerous. Living things can be harmed if nuclear energy isn’t handled safely.
• Uranium is a non-renewable energy resource.
One day there will be no uranium left to use.
• Nuclear energy creates waste. This waste is very dangerous for many years. It costs a lot to store this waste.
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THERMAL-ELECTRIC ENERGY
Thermal-electric power plants turn chemical energy into electric energy. Special substances called fossil fuels are burned, which produces thermal energy. The thermal energy turns water into steam. The steam spins turbines to produce electricity (Figure 4).
Fossil fuels are found deep in Earth. They are parts of plants and animals that died millions of years ago. We burn them to change their chemical energy into
thermal energy. They produce more energy than wood.
Examples of fossil fuels include
• oil
• coal
• natural gas
Fossil fuels can be helpful. There are also problems with fossil fuels. Table 1 lists some good and bad points of using fossil fuels.
Over 80 % of global energy used comes from fossil fuels. This can be a problem in the future. People must find more renewable energy resources. We may use up all available fossil fuels during our lives.
fossil fuels
concentrated sources of chemical energy such as coal, oil (petroleum), and natural gas that were formed deep in Earth’s structure over millions of years from decayed and
compressed plant material
Good points of fossil fuels Bad points of fossil fuels
easy to move around non-renewable
not too expensive causes pollution
can be used for many different things: only found in some parts of the world electricity, heating, transportation
Table 1 Good and Bad Points of Fossil Fuels
Figure 4 A cross-section of a coal fired thermal-electric power plant steam
turbine
fossil fuel
electrical energy generator
condensed water
return water line
1. What are three conventional energy sources?
2. What is a renewable energy resource? What is a non-renewable energy resource? Give an example of each.
3. Think back to the Key Question. Complete the chart by writing the good points and bad points of each type of energy source.
Good points Bad points
Fossil fuels
Hydro-electric
Nuclear
CHECK YOUR UNDERSTANDING
Name: _________________________________________ Date: ________________________
