Page 164 - Science Coursebook

11.2 Fossil fuels

An energy resource is anything from which we can obtain nuclear
energy. The pie chart shows the energy resources we use, and
the fraction of our total needs each type contributes. renewables oil

You can see that most of the energy we use comes from
fossil fuels. These are coal, oil and natural gas.

Question gas
1 a Which fossil fuel is used the most as an
energy resource?
b Use the pie chart to estimate the fraction of our coal
energy which comes from fossil fuels. The energy resources we use around
the world.
Chemical stores
In Stage 7 Unit 10 you learnt about how energy changes
from one form to another. Fossil fuels are stores of chemical
energy. The energy is released when the fuel is burnt.

For example, in a car engine, petrol and air are mixed
together. A spark ignites the mixture and it burns. The
energy released makes the car move forward.

Fossil fuels are useful because they are very concentrated
stores of energy. It takes only a minute or two for a driver to
put 50 litres of petrol into the car’s tank. Then it is ready to

travel 1000 km or more. Refuelling a taxi with petrol at a filling
station in Borneo.
Questions

2 What name is given to the energy of a moving car?
3 Many people use oil to heat their homes. Draw a
diagram to show this energy change.

Where the energy came from
Fossil fuels are found underground. Coal formed from the
remains of plants that died millions of years ago. Oil and
gas formed from the remains of sea creatures.
Those living organisms gained their energy originally from
sunlight. So, when we burn fossil fuels, we are making use
of the energy of sunlight which fell on the Earth a very
long time ago.

Question
4 Why is it wrong to say that fossil fuels are stores
of light energy? In some parts of the world, oil and gas
are extracted from under the seabed.

162 11 Energy

A+I A+E SE