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Lesson 8: Generating electricity

Electricity is a secondary energy source, this is an energy source which does not

exist in nature but is produced from a primary energy source such as fossil fuels.

There are a number of primary energy sources that can be used to generate

electricity:

Fossil fuels: Coal and gas are examples of fossil fuels, but they will

eventually run out. When a fossil fuel is burned in a power station it will

release carbon dioxide (CO2) into the atmosphere, adding to the problem

of global warming.

Nuclear fuel: Uranium is used as fuel in nuclear power stations. Nuclear

power stations do not produce CO2 but do produce nuclear waste, which is

very dangerous.

Renewable energy sources: Solar, wind, tidal and geothermal power

can be used to generate electricity. These sources will never run out and

do not produce CO2.

In your exam you may be asked to identify different primary energy sources that

can be used to generate electricity.

There are advantages and disadvantages of using these different primary energy

sources to produce electricity.

Energy source Advantages Disadvantages

Coal Coal is cheap and easy to

obtain.

High efficiency

High power output.

Cheap electricity.

Produces lots of CO2 which

contributes to global

warming.

Produces acid rain.

Need to mine coal, which

can damage the

environment.

What you need to know:

1. Different energy sources can be used to generate electricity.

2. There are different types of power stations.

3. How to use a Sankey diagram.

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Technology is easily

available to build coal

fuelled power stations.

Some countries need to

import coal, meaning they

are reliant on other

countries. This means they

are not secure for their

energy generation.

Coal will eventually run

out.

Gas Efficient at producing

electricity.

Cheap electricity.

Technology is easily

available to build coal

fuelled power stations.

Produces CO2 which

contributes to global

warming.

Difficult to transport.

Some countries need to

import gas, meaning they

are reliant on other

countries. This means they

are not secure for their

energy generation.

Gas will eventually run out.

Nuclear Very cheap electricity.

Low levels of CO2

produced.

Very high efficiency.

Produces nuclear waste.

Building and

decommissioning power

stations is difficult and

costs are high.

Solar power No CO2 produced.

Easy to build power

stations.

Low efficiency.

Small amounts of

electricity produced.

Source not constant.

Wind No CO2 produced.

Easy to build power

stations.

Cheap electricity.

Need lots of turbines to

produce electricity.

Wind is not constant.

Visual pollution.

In your exam you may be asked for some advantages and disadvantages of

these different energy sources.

© Studydoctor 2009

Power stations use the heat generated from burning fossil fuels and the fission of

nuclear fuels to boil water, making steam. This steam drives a turbine which

produces electricity. The efficiency of a power station can be described in

a Sankey diagram, which shows where the energy created from a fuel

source is going.

As you can see, not all the energy generated from a fossil fuel actually goes into

making electricity, lots of the energy is wasted.

In your exam you may be asked to use a Sankey diagram to work out the

efficiency of a primary energy source used to generate electricity.

Recap:

1. Electricity is a secondary energy source that is generated from a primary energy

source.

2. Each energy source has its advantages and disadvantages.

3. A Sankey diagram can be used to show the efficiency of energy sources in generating

electricity.

Electricity

Exhaust gases

Cooling steam

25%

30%

45%