Chemistry Reference
In-Depth Information
●
What is a fuel?
A fuel is a substance which can be conveniently used
as a source of energy. Fossil fuels release energy in the
form of heat when they undergo
combustion
.
fossil fuel + oxygen → carbon dioxide + water + energy
For example, natural gas burns readily in air
(Chapter 14, p. 220).
methane + oxygen → carbon + water + energy
dioxide
CH
4
(
g
) + 2O
2
(
g
) → CO
2
(
g
) + 2H
2
O(
l
)
It should be noted that natural gas, like crude oil,
is a mixture of hydrocarbons such as methane (main
constituent), ethane and propane, and may also
contain some sulfur. The sulfur content varies from
source to source. Natural gas obtained from the
North Sea is quite low in sulfur.
The perfect fuel would be:
●
cheap
●
available in large quantities
●
safe to store and transport
●
easy to ignite and burn, causing no pollution
●
capable of releasing large amounts of energy.
Solid fuels are safer than volatile liquid fuels like
petrol and gaseous fuels like natural gas.
Figure 6.9
A Hongkong Electric Co. Power Station, Hong Kong, China.
waste
gases
steam
generator
steam
turbine
heat
from
burning
fuel
water
grid
system
Question
1
'We have not yet found the perfect fuel.' Discuss this
statement.
transformer
Figure 6.10
The way in which fuels are used to produce electricity.
Other major uses of the fossil fuels are:
●
as major feedstock (raw material) for the
chemicals and pharmaceuticals industries
●
or domestic and industrial heating and cooking
●
as fuels for various forms of vehicle transport.
How are fossil fuels used?
A major use of fossil fuels is in the production of
electricity. Coal, oil and natural gas are burned
in power stations (Figure 6.9) to heat water to
produce steam, which is then used to drive large
turbines (Figure 6.10). A high proportion of the
electricity generated worldwide is derived from
fossil fuels. However, it should be noted that the
relative importance of the three major fossil fuels is
changing. Coal and oil are becoming less important
while natural gas is increasingly important.
In a power station, the turbine drives a generator
to produce electricity which is then fed into the
national grid (Figure 6.10). The national grid is
a system for distributing electricity throughout a
country.
Question
1
'Fossil fuels are a major feedstock for the chemical and
pharmaceutical industries.' With reference to Chapters 14
and 15, give examples which support this statement.
