Download Fossil Fuels

Fossil Fuels
What are fossil fuels ?
• A fuel is any substance used as a source of
energy, usually heat energy.
• Most of the world’s energy is provided by
the burning of fossil fuels ( 化 石 燃 料 ).
Fossils fuels are natural combustible
substances formed originally from dead
plants and animals.
Fossil Fuel (http://www.enviroliteracy.org/fossil_fuels.html)
• The major fossil fuels are
– coal (煤),
– petroleum (石油) and
– natural gas (天然氣).
• Fossils fuels are non-renewable (非再生能
源) energy sources. This is because fossil
fuels take millions of years to form. Once
they are used up they can never be replaced.
World Fuel Resources
Petroleum
or Oil
Natural Gas
Coal
Power
reserves
130 billion
tonnes
158 billion
cubic metres
950 billion
tonnes
Total used
in 1990
2.2 billion
tonnes
1.5billion
cubic metres
2.2 billion
tonnes
From the above table, the present world's estimated oil
reserves may be used up in the next 50 to 60 years.
Coal
How was coal formed?
• Coal is the plants that grew in swampy
areas about 300 millions ago. The plant
grew and died to form layers of decaying
material. Heat, pressure and the action of
bacteria changed the decaying plants into
coal.
How is coal used?
• Today, about 70 % of the total coal mined is
burned in power station.
Coal Education (http://www.coaleducation.org/)
Petroleum
1. How was petroleum formed?
• Petroleum was formed from small sea
animals and plants that lived millions of
years ago. After they died, heat; pressure;
and the action of bacteria changed the
remains into oil. The oil formed was then
trapped as small drops inside the pores of
rocks.
Petroleum (http://www.petroleum.co.uk/)
How is petroleum used?
• The thick crude oil that comes from the
ground is a complex mixture of compounds.
It is necessary to separate the compounds.
(We will discuss this method which is used
to separate crude oil in the section 5.2) The
separated substances have two main uses:
– as sources of useful fuels. e.g. petrol
– as raw materials to make other products. e.g.
plastics, detergents.
Natural Gas
• Natural gas is found together with oil and
sometimes with coal.
• The gas consists mainly of methane CH4.
Natural Gas (http://www.naturalgas.org/)
• In some countries, the gas is carried by
pipes to homes and factories for heating and
cooking.