2. Where do we get energy from? We get
energy from the food we eat. A substance
that produces energy on burning is called
a fuel.
Hence , food can be thought of as a fuel
for our body.
3. TYPES OF FUELS
Fuels are available in solid , liquid or gaseous
form.
Wood , coal , coke and cowdung cakes are
some examples of solid fuels.
Liquefied Petroleum Gas (LPG), Compressed
Natural Gas (CNG) and biogas are examples of
gaseous fuels. Kerosene, petrol and
diesel are examples of liquid fuels.
4. USES OF FUELS
Fuels produce energy on burning. Energy is
required for many purposes. For producing
energy, different types of fuels are used in
different situations.
5. DOMESTIC FUELS
Cowdung cakes, coal and kerosene are
commonly used domestic fuels.
These fuels are used even now, in some
households in villages.
In cities , and in many villages, gaseous fuels like
LPG and biogas are now commonly used as
domestic fuels.
These are cleaner fuels as they do not produce
smoke on burning and do not leave
any ash after burning.
6. FUELS FOR TRANSPORTATION AND ELECTRICITY
GENERATION
Trains were earlier run with the help of steam
engines.
In these engines, steam was produced by burning coal.
Nowadays, train engines use either electricity or diesel.
7. Vehicleslike buses, cars, scooters, trucks and tractors run on
petrol or diesel.
Many buses and cars now use CNG as fuel.
CNG is called a green fuel because it causes less air
pollution and is more eco-friendly.
Aeroplanes use highly refined petrol as fuel.
8. DO YOU KNOW?
Electricity, generated by using the energy of
water, falling from a height, is called hydro-
electricity.
9. FUELS AND MACHINES
• Earlier, household works like washing clothes,
spinning, weaving, and so on were done
manually. This was time consuming, slow and
tiring.
• Hand-operated machines were then
developed to help us. Later on, machines
working through steam were invented.
10. This resulted in an increase in the demand for coal. The
reserves of coal, in nature, started depleting rapidly.
To meet these challenges, steam engines were gradually
replaced by other engines which used liquid fuels like petrol
and diesel.
However, petroleum reserves in nature are also limited
and cannot be replenished easily.
11. FOSSIL FUELS
• Fossil fuels are fuels that are formed by
decomposition of animal and plant matter,
buried deep under the surface of earth, at
high temperature and pressure.
• This animal and plant matter changes into
fossil fuels over a period of millions of years.
Coal, petrol and diesel are fossil fuels.
12. RENEWABLE AND NON-RENEWABLE
SOURCES OF ENERGY.
• Sources of energy, which once used, cannot be readily
replenished are called non-renewable sources of energy. Coal
and petroleum are non-renewable sources of energy.
• There are some sources of energy which are freely available
and which can be readily replenished. They are called sources
of energy. Solar energy, water, wind and biomass are
examples of renewable sources of energy.
